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HomeCNC
03-20-2003, 07:41 PM
This is my first router I have designed from scratch. I am designing it around the linear ways that I got from e-bay.

I am building the spindle right now. I chose to not go with a router because of the excessive noise and not being able to use my R-8 collets from my mill. I am going to power the spindle with a DC motor so I can get variable speed. If I run the pulley system on a 1:2 I can get 5000 RPM which will be fine for my use.

cncadmin
03-21-2003, 06:02 PM
Great looking router design.I like your placement of the guiderods

and bearings on the Y axis. I have questions about your spindle

motor speed.....isn 't 5000 Rpm too slow for a wood router?

For a 1/4" wood bit I would think 25-30,000 Rpm .

HomeCNC
03-22-2003, 01:08 PM
Normal wood routing uses 2 flute router bits. I will be using solid carbide 4 flute end mills with this machine. I not only want to machine wood, but metal as well. My shaper table in my wood shop only turns about 5000 RPM and has no problems with wood cutting in surface quality even on end grain.

cncadmin
03-25-2003, 11:37 AM
What is the cutting IPM?

HomeCNC
03-25-2003, 01:58 PM
MasterCAM says the feed rate for wood with a 4 flute cutter running at 5000 RPM would be 50 IPM. This will be no problem. My setup using .200 pitch ball screw stock running on a 2:1 ratio with my servo motors I can get 76 IPM on a linear move.

E-Stop
03-25-2003, 02:55 PM
Very interesting. I have been considering building a CNC router for about a year now. I've done a little work on the design but not near what you have here. I've got the linear rails for the "X" and "Y" and an almost complete "Z" axis slide unit. Plans are to use a router (which has already been bought and is still in the box). What size of work envelope is your router? The rails I got are 110" for the "X" axis and 56" for the "Y" axis. I wanted to have a work envelope of at least 8 feet by 4 feet so that we could work on an entire sheet of plywood, if needed.

Please keep us posted of your progress. And when I get started, I'll post some pictures as I go.

HomeCNC
03-25-2003, 11:01 PM
E-stop, You are thinking of a much larger router than I am building. My X rails are 42" long and my Y rails are 28" long. I have a work area of 24 X 24. My Z rails are 18". I want my router to sit on a table I have.

Are you designing your table to be stationary like mine, or are you going with a moving table with a stationary up right?

E-Stop
03-26-2003, 10:30 AM
The table will be stationary and the gantry style head will travel. Making the table move would require about twice the floor space of the stationary design. With a 4' x 8' work envelope, it's going to take up a good chunck of real estate anyway.

I forgot to mention it but the Z axis unit is on 18" rails.

One thing I found interesting in your drawing is the placement of the Y axis rails. I have been trying to decide which way to mount the rails. The two choices were mounting them parallel to the table or perpendicular to the table. In your design I see the two rails are not in either of these orientations but kind of one each way. What factors influenced your decision to mount them this way? Is there an advantage of one way over the others? I like the looks of yours and I am considering changing mine but first I want to weigh all the details.

HomeCNC
03-26-2003, 02:44 PM
The main reason I placed the Y rails in the postion shown was because if the rails were side by side on the vertical plane the all the balls at the top of the bearings would be taking the wear.

Also after I started to look at this design more, I also liked the fact that I can adjust the top rail to help square up the spindle to the table in the X direction. I will use the spindle mounting screws to square it up in the Y direction.

HomeCNC
04-08-2003, 12:44 AM
I managed to finish my Servo controller box this weekend. It worked great! I used a torid for the transformer this time. Wow do I like them.

HomeCNC
04-08-2003, 12:46 AM
I got a little carried away with the front grill. I painted it black and engraved the lettering in with my CNC mill.

cncadmin
04-08-2003, 03:46 PM
Nice work keep the pics coming...

HomeCNC
04-13-2003, 11:06 PM
I had a very good weekend, I was able to get most of the frame finished. The detail work of fitting the ball screws and bearing will be coming soon. I wish Reid Tool would get my Ball screw and ball nuts off of backorder! It's been almost 3 weeks now.

balsaman
04-14-2003, 07:43 AM
Great looking machine! Very nice. Keep the pictures coming.

Your shop is much too neat....could you mess it up a little before taking any more pictures...I am worried my wife might see it..:)

Eric

E-Stop
04-14-2003, 09:57 AM
O.K. I'm jealous. I'm still at the beginning stages of putting everything into perspective. I might be analyzing things a bit too much. Or you just make it look simpler than it is.

HomeCNC
04-14-2003, 11:04 AM
I’m also surprised about how easy it’s going together. So far I just been machining the bar stock to the proper length and then drilling the holes in the proper spot. (lots of tapping). It seems to be going together great! I did need to slot the mounting holes in the upper Y-axis rail to get it so the Z-axis plate was parallel to the gantry (I used my calipers to check the distance).

Balsaman – If you could only see what is behind the camera! I can’t back up any farther than where I took the picture, because of all the crap around me and on the floor. :)

Zephrant
04-15-2003, 02:10 PM
Looks great- I have also been thinking about using a motor/spindle setup with R8 collets. Can you provide a little more detail there? Is the motor mounted to the movable potion of the Z axis? Will you be supporting reverse?

I was considering finding a used cheapo mill and taking the motor/geared-head assembly as well as the quill, and mounting it on the back side of my gantry. Then I could manually dial in the speed as needed, and use a quick-change R8 collet system to drill and tap as needed (I have a Tapmatic tapping head).

I was also considering using a stepper to drive the drill portion. Then I could create a tapping motion- Forward at a certain RPM, with a certain feed rate, then reverse and back out of the threads. A quick-change setup that replaces the router with this setup might be more feasible, but I'm concerned about the software control of the RPM. Anyone think I could use a 4-axis system to control the table + drill RPM?


Zeph

balsaman
04-15-2003, 02:13 PM
I am wondering if a stepper has the speed/torque to do tapping.

Eric

Zephrant
04-16-2003, 12:31 PM
Me too. I don't need high-speed tapping though, so 120 RPM would be plenty fast. I just can't see mounting a huge 2 HP AC motor (like what is on my Jett mill) on a CNC table. Too much mass to move around when the router head is being used.

Zeph

HomeCNC
04-16-2003, 04:12 PM
This is the area of my design that I'm not sure about yet. My plan was to find a DC motor and run it with a SRC speed control. Use a 2:1 ratio to get around 5000 RPM. I have having trouble finding a DC motor that will not weigh so much and do 2500 RPM at 90 VDC. I will mount the motor and spindle to the Z-axis slide. My concern is weight.

I can always fall back on getting a standard router. I just wanted something that was not so loud.

Zephrant
04-16-2003, 07:21 PM
Man, I hear you there... I'd like to be able to run the machine late at night when the wife is asleep, but between the router and the dust collector I'm afraid it will be too loud.

My Jet mill is so much quieter than the 2hp router. I would gladly sacrifice some cutting speed for a quieter machine though.

Zeph

balsaman
04-17-2003, 12:20 AM
Use a flex shaft? Perhaps you could scrounge some parts off an old gas weedwacker....They have 1/4" flex shafts in them.

Eric

Zephrant
04-17-2003, 05:19 PM
How about something like this:
Servo (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2522827287&category=11806)


800 oz-in of torque, 3000 rpm, 1.95 HP all for $50.

Hook that up to your x2 pulley system to get to 6k rpm, and you might be set. Or find a high-speed 1:2 gear box, and not deal with any belts.

Zeph

HomeCNC
04-17-2003, 06:28 PM
What they don't tell you is it takes 230VAC to run that motor. Still could be an option.

HomeCNC
04-18-2003, 10:53 AM
I think I may have found a motor that will work. Check out

http://www.sciplus.com/category.cfm?subsection=18&category=174

It is 120VDC and 4800 RPM.

The weight will still be high, so I think I will change the servo ratio to maybe 3:1 or 4:1 I will need to do some calculations for the weight. I may need to get a stronger servo motor for the Z axis.

HomeCNC
04-20-2003, 01:51 AM
This detail work is taking so long. I managed to get the ball screw in for the Y axis.

Maybe on Easter I can mount the first servo motor to run it!

HomeCNC
04-23-2003, 11:38 PM
I got the first servo motor on and running tonight! This is great! Oh I get excited easy. :D My laptop would only let it run a 91 IPM.

cncadmin
04-23-2003, 11:49 PM
Wow, very nice it's coming alone well, I wish my machine was servo driven! :) Kepp those pics coming.

WOODKNACK
04-24-2003, 12:19 PM
You should do a movie clip on your site of the machine moving its 3 axis. I enjoy watching those! Good job!!!

HomeCNC
04-24-2003, 04:17 PM
Yes, I have been meaning to add more movie clips to my site. The one I have is getting old.

HomeCNC
04-27-2003, 01:26 AM
This animal is getting heavy. I think by the time I'm done it will be over 300 lbs. I decieded to build a steel table to hold this thing I think it will be better because I can keep the electronics, computer and Vacuum pump under the table on a shelf I will put there. Wow I have not welded since High School! About 25 years ago, and it shows :D

kong
04-27-2003, 01:31 PM
This really is shaping up to be a supreme machine! One day I'll be as good as you! One day!:(

HomeCNC
04-30-2003, 12:37 AM
I finished the stand and moved the router off my out feed table from my wood shop onto the stand. I hope I'm not posting to many pictures :confused:

paulried
04-30-2003, 12:46 AM
Keep the pictures coming....I love it. Your router looks great

Tompie
05-01-2003, 06:25 PM
That realy is a nice router...do you sell the planes for it?

HomeCNC
05-02-2003, 02:34 PM
When I finish this router and use it, I will evaluate it's performance. If it performs well I will most likely add this set of plans to my existing drill/mill plans.

HomeCNC
05-03-2003, 11:58 PM
I have now connected the X and Z axis up. I'm trying Mach 1 for the first time. Using a PIII 500, Mach 1 drove the servo's at 150 IPM! I will be looking hard at purchasing Mach 1.

It was also fun to jog the machine using a Joystick!! :D

kong
05-04-2003, 08:31 AM
That must be oh such a good feeling! Did you sort out your spindle motor yet? I'm just interested in seeing some movies of that thing cutting!:D

coherent
05-04-2003, 11:22 AM
Nice job, looks great. You won't regret buying mach1. I'm a registered owner and am very pleased. Art's support is outstanding, he'll go out of his way to help with any issues you may run into.
-Marc

HomeCNC
05-04-2003, 01:29 PM
Kong, I just can't find a DC motor that is strong enough as well as light weight to run my spindle. I decieded to purchase a Porter Cable variable router. It has 5 speeds from 10,000 to 22,000 RPM. Maybe I can use the lower speed to keep the noise down. Anyway at least I will be cutting soon :)


Oh! I am also going to design some collet holders for the router so I can hold cutter in a holder and be able to use tool length offsets.

anoel
05-04-2003, 02:50 PM
Damn....

ger21
05-04-2003, 03:53 PM
Hey Jeff, is that the big Porter cable (3 1/4HP) or the 1 3/4HP. I was thinking about buying that 1 3/4 for the VS, but I might buy one of those cheap router speed controls and use one of the 690's I already have.

Gerry

HomeCNC
05-04-2003, 07:33 PM
Yep! I ordered the 3 1/4 HP from Amizon.com's tools site.

ger21
05-04-2003, 11:31 PM
I've got one of those too, but it's too heavy for the machine I'm building. Great router, too. And it is reasonably quiet at the slow speeds.

Gerry

tsalaf
05-06-2003, 09:59 AM
I just purchased the Makita RF1101 for a small router I’m building (10" cube work envelope). 21/4 HP with 8000-24000 rpm. The other two larger Makita routers I use for work have been very reliable over the years, sometimes working non-stop for 8 hour shifts. This may be a good alternative to the Porter-Cable

HomeCNC
05-09-2003, 12:43 AM
It was on my door step today! Wow it looks great and even runs better. The slow speed @ 10,000 is not very noisy at all. I think I am going to like that I went this way. I'm now designing a mounting flange for it. Maybe I can have this CNC machine ready to cut something by the end of this weekend. :D

deanc500
05-09-2003, 09:53 AM
Hi Jeff, here is the mount I designed for the 3 1/4 hp porter cable.
http://www.members.shaw.ca/axxus4/porter%20cable/

HomeCNC
05-10-2003, 08:32 PM
Oh! You mean something like this :)

HomeCNC
05-10-2003, 08:35 PM
I just finished the first collet that fits a Porter Cable router. This will hold a 1/4" bit at a fixed location. I now just need to make two each for 1/8", 1/4", 3/8" and 1/2". Then I can hold both standard and ball cutter for each size.

HomeCNC
05-10-2003, 08:36 PM
And here is the collet in the router. It ran very straight and smooth.

Now on to finish the table top. I have all the tee slot bars made. I am now mounting them to the plate.

More to come!!!

tsalaf
05-10-2003, 08:44 PM
Jeff,

The collet looks great. Does it seat at the same depth in the spindle after repeated removal and intallation?

HuFlungDung
05-10-2003, 10:33 PM
Yes, very nice looking design.

HomeCNC
05-11-2003, 12:13 AM
Tsalaf, That is the idea behind the fixed collets. The taper on the collet matches the taper in the router. The nut just holds them together.

ger21
05-11-2003, 12:38 AM
Hey Jeff, any chance you might offer those for sale? Porter Cable 690's also use the same collet, btw.

Gerry

HomeCNC
05-11-2003, 12:24 PM
Ger21,

Do you mean the drawings or do you mean the parts? I really don't have the time to create parts, but if anyone wants the drawings for the collets I can post them. What I did was purchase extra Porter Cable collets so I could get the nut and snap ring. I take them appart and use them on the new fixed collets.

balsaman
05-11-2003, 01:12 PM
Hi,

Yes, I would be interested in the drawing. Please post them if you can....Very nice job, and a great idea! Fantastic cnc router.

Eric

ger21
05-11-2003, 03:22 PM
Actually, I was thinking of the parts. I probably won't have my router complete until sometime this winter, so I don't need them now anyway.

Gerry

HomeCNC
05-12-2003, 12:05 AM
Before I give out any design prints I want to see if it works! I hate making something available to others and find out it does not work :(

I will do proper R&D work before I let it go.

cbcnc
05-12-2003, 01:15 AM
Hi Jeff,

That is a really good idea. It is along the lines of milling machine collets. I have been thinking of just an insert to my normal collet (1/4" in my case) to handle 1/8" bits.
I wonder if the bit is going to be held in there tight enough with just the setscrew. I don't see any compression slits. Do your bits have a flat in them?
Now what we need is the same kind of collets in 1/16", 1/8" & 1/4" for the Porter Cable 7310 and 310 series trim routers. Since alot of us are using those routers.

Chris

georgebarr
05-12-2003, 05:31 AM
Originally posted by HomeCNC
I managed to finish my Servo controller box this weekend. It worked great! I used a torid for the transformer this time. Wow do I like them.

How did you make the metal enclosure? Did you make it or buy the enclosure. I would sure like to know how to make one.

georgebarr
05-12-2003, 06:28 AM
Originally posted by HomeCNC
I had a very good weekend, I was able to get most of the frame finished. The detail work of fitting the ball screws and bearing will be coming soon. I wish Reid Tool would get my Ball screw and ball nuts off of backorder! It's been almost 3 weeks now.

Whats the size of your cnc machine in x", y", z"? I am currently designing my cnc and just wanted some info. I plan to use aluminum extrusion since it will greatly simplify the frame construction. I do not have much experience constructing things so extrusion is a safer method for me.

HomeCNC
05-12-2003, 08:33 PM
X travel is 29.5. Y travel is 24. Z travel is 7.

I was shooting for 24x24x6.

HomeCNC
05-12-2003, 08:37 PM
I was able to get the table together this weekend. I got all the Tee bars mounted to the plate, and then bolted the plate down to the router.

I took vacation today so I worked on my router all day :) I tramed the router in with a dia indicator and got it within .010 TIR in a complete circle of about 12". After that I placed a 1.5" cutter in the router and started to surface the top of the aluminum flat.

HomeCNC
05-12-2003, 08:40 PM
I don't know how the camara caught the bit so clear. It was moving at 18,000 RPM. Also I was trying to not get hit by aluminum chips!

HomeCNC
05-12-2003, 08:42 PM
I'm running Mach 2 now. Art told me that Mach 1 was not for me after I told him what I wanted in a controller. It runs very nice for beta software.

HomeCNC
05-12-2003, 08:47 PM
George.

I just saw your question above about the box I built my controls inside of. I got the box from Mouser. http://www.mouser.com

cncadmin
05-19-2003, 10:14 PM
Any more updates?

HomeCNC
05-20-2003, 03:05 PM
Working on my tooling. Will post pics soon.

kong
05-20-2003, 03:18 PM
Looks fantastic, good job, just wondering what cutter you have in the router for the aluminium, router bit, or end mill?

HomeCNC
05-20-2003, 10:09 PM
Well I have a set of fixed collets for my Porter Cable router. I'm still working on the 1/2" ones. They will need to be build a little different. There is not much meat for the set screw to hold the bit. I need to make it larger on the diameter and open the nut larger.

I have all the tools up to 3/8" for flat and ball end. I just don't have the 1/16" flat yet. Come to think of it I may never use the 1/16" flat mill anyway :D

HomeCNC
05-20-2003, 10:12 PM
Kong, The tool I used to surface the aluminum table was a router bit. I looked at my local woodworking store for the largest bit they had. It was a 1.5" dia two flute.

tsalaf
05-21-2003, 06:35 PM
Jeff, did you use a manual or cnc lathe to make the collets?
How did you measure the angles on the original P-C collet?

HomeCNC
05-22-2003, 12:06 PM
I used my manual lathe to build the collets. Good question about the angle. I have asked Porter Cable and got no help so far. I did my best to measure the slit collets that came with the router. I used dial calipers. This got me close. I started with a scrap piece of aluminum and cut the first taper. I test fitted it inside the router and made small changes from there. Once I got a good fitting taper I scratched a line on my compound and that is what I have been using. I don't have degree lines on my compound so I still don't know what the true angle is.

HomeCNC
05-22-2003, 10:35 PM
As I post this my router is doing the finish cuts to my first part cut on the machine. My fixed tooling is working great! I have made three tool changes and they all have indexed back to the part great.

Below is the picture of what I am cutting. This is just a demo file from ArtCam Pro.
Except that I added the griffens in the center :)

HomeCNC
05-22-2003, 10:36 PM
Tool # 7, 3/8 end mill. .040 above the finish surface.

HomeCNC
05-22-2003, 10:38 PM
Tool # 4, 1/8 Ball Mill .010 above the finish surface. .007 step over distance.

HomeCNC
05-22-2003, 10:40 PM
Tool # 2, 1/16 Ball Mill. Zero clearance, right on the surface. .003 step over distance.

I think this is going to be not worth the wait to get the extra detail. The 1/8 ball mill did a nice job. This tool path will take about 6 hours to complete. I think next time I will only select the detail areas that I want done, not the entire part.

kong
05-23-2003, 08:31 AM
This really shows off the quality of your setup. Nice work.

HomeCNC
05-23-2003, 11:57 AM
I started at 4:00 PM and finished at 1:00 AM. That last finish pass was LONG!!!

cncadmin
05-23-2003, 12:12 PM
Very nice work, now I really wish I did'nt sell my machine.

coherent
05-23-2003, 01:57 PM
Jeff... very nice job. I've got the simple cuts down, but haven't tackled the more intricate stuff like this. It would really be helpful to see a brief explanation of software/steps used to create this. Was the final gcode 4 seperate files or a single with tools changes programed in? Any chance of sharing the gcode files? Again, great work!
-Marc

E-Stop
05-23-2003, 02:07 PM
Excellent. Reading thru this thread and visiting your website has given me more inspiration than needed to get going on my router. As I mentioned before, it will be almost 9' x 5' x 18". I am using the same Porter Cable router that you used for the spindle, which leads me to this question:

What RPM were you using for the finish cut and did the router have any heat problems running non-stop for 7 hours?

Again, great job on the router, the work piece and on keeping us all up to date via your postings.

HomeCNC
05-23-2003, 09:08 PM
The Crest was already created relief from ArtCam. It was 3D scanned from a real part. You can tell this because it has way to much detail that can be created with the tools in ArtCam. The crest was blank in the middle and I felt it needed something. I found the griffen relief on a ArtCam clip art disk. It was easy to past the griffen onto the Crest center. Once I had the completed model, I created my tool paths. My first one was the roughing pass using a 3/8" end mill. I told it to Z slice the whole part and stay away from the finished surface by .040.

The next tool path was something I called the 'Cutout'. I wanted the background surface all flat, and if I used a ball cutter over the entire part it would not be nice and flat on the background. I told the tool to trace around the outside of the object and remove all the material to the boarders edge. This cut was at final depth for the background. I used a 1/4" end mill. After this I used a 1/8" end mill for rest milling to clean up all the areas that the 1/4" tool could not get to.

The next tool path was the first 3D surface path. I used a 1/8" ball mill and told it to only do the object but could go outside the object by only 1/8". This cut stayed .010 above the final surface and was at .007 step over. This is the tool path that I should have used as the final. It took under 2 hours to complete these steps.

I wanted even more detail so I created the final 3D tool path using a 1/16" ball mill. This went over the same area as the 1/8" ball mill but this time it had a step over of .003 and was down to the finished surface. This path took about 7 hours. I should have only told the 1/16" bit to do the center griffen and it would have been fine.

I had to output the Gcode in seperate files because the post I used was for generic inch Gcode and did not support tool changes. I added them manualy along with the fixture offset of G54 and the tool offset of G43 H?

I had to use CNCPro because Mach 2 still has some problems in the area of fixture offsets and tool lenght offsets.

HomeCNC
05-23-2003, 09:14 PM
E-stop,

I used the second speed of 18,000 for the roughing pass because it was going at 100 IPM, and a depth of .200. After that I did all the other cuts on the slowest speed of 10,000. The router was not hot at all. The bits got very warm, but I could still handle them for the tool changes.

I must say that fixed tooling is a must when you are doing this kind of work. After the first roughing pass, the top of the material was gone. This means that I lost the top of stock were Z zero was set. Since I already know my tool lenghts it does not matter :)

HomeCNC
05-23-2003, 09:21 PM
Well, you have it all here on CNCZone. My entire creation and building of my CNC router documented right here :D

All that's left for me to do to complete this project, is to install the Home and limit switches and wait for Mach 2 to be finish and working.

I will be working with my cousin do get a movie on my web site soon. I will let you know when it's there.

Wjman
05-26-2003, 02:18 AM
Jeff,
After reading yours and many other postings on this forum, I am going to build a CNC router, It may take me a little while to gather all the "bits" together, but I am itching to try. If I could call on your or anyone elses help, I would be grateful. Thanks to everyone for the input.
This is by far, the most informative and interesting site I have been on (I sit for ages reading various posts).
Mark...

Klox
05-26-2003, 12:04 PM
I must say that I am impressed!!

Klox

HomeCNC
06-04-2003, 03:12 PM
O.K. I got my Home switches in and last night I built my first I/O relay to turn on and off the router motor. With help from Dean from Axxus Tech. (I have his interface card) I was able to build a nice little relay box. I just place a M03 at the start and a M05 at the end of the Gcode.

Oh it is so nice to not need to wait for a long Gcode program to finish so you can turn off the router. I just go to bed and in the morning it is done and the router is off!!!

balsaman
06-04-2003, 03:32 PM
Yeah, if you are brave! Just when you leave all hell breaks loose!!

I too have a relay driving the spindle. It's great! Now I just need software speed control....:)

Eric

HomeCNC
06-12-2003, 12:17 PM
I had a filming session yesterday. My cousin came over with all his digital ‘stuff’ and I went through the process of setting up the router for cutting a part. I should get a few movies out of this. It was fun to watch the ball tool run over the hills and dips of the part. I will let everyone know when they are up on my web site.

wjbzone
06-13-2003, 04:24 PM
Jeff,

I hope to get that motor relay working this weekend. I just got a Crydom solid state relay that switches up to a 240Vac 40Amp output based on a 5vdc input.

I know where to hook the positive 5vdc, but still need to figure out the ground for the 5v.

I can already feel that relief of being able to use M3/M5.

Bill.

andybuch
06-20-2003, 11:17 AM
Originally posted by HomeCNC
O.K. I got my Home switches in and last night I built my first I/O relay to turn on and off the router motor. With help from Dean from Axxus Tech. (I have his interface card) I was able to build a nice little relay box. I just place a M03 at the start and a M05 at the end of the Gcode.

Oh it is so nice to not need to wait for a long Gcode program to finish so you can turn off the router. I just go to bed and in the morning it is done and the router is off!!!


Jeff do you have any pictures of your home & limit switch set-up? How did you set-up the switches on the same end of the axis?

Andy

HomeCNC
06-23-2003, 11:42 AM
Fired up Cadkey for this sketch.
Below is a drawing showing one axis connection to the LPT interface card. I use the Axxus card. I used Pin 10 , 12 and 13 for X, Y and Z Home and Limit. Pin 11 is different about the Axxus board so I did not use it. You can have a different pin for Home and a different pin for Limit but I did not want to use so many pins for this. I needed pins for I/O use as well.

The best (safest) way to connect the switches is to use the closed method. This way if there is a break in the circuit or a power failure your software will trigger a limit stop. Connect all three axis as below.

wjbzone
06-30-2003, 08:24 AM
Jeff,

I know you said your fixed tool holders are working out great. Do you find any problems with them after a few weeks of use?

I just finished a job that made me wish I had a set like yours. I hope you can answer some questions:

1. How tight is the fit in the bore that accepts the tools.

2. Do you preset your tool lengths, or just measure and store lengths in a tool file?

3. Do you grind a flat on the side of the tool for the set screw?

4. Do you notice any vibration or out of balance conditions?

I appreciate advice you can provide.

Thanks,
Bill

HomeCNC
06-30-2003, 01:13 PM
I have been using them with great results! Even being made out of soft steel 1018 they seem to work fine. I have been approched by someone who offered to produce them for me to sell, and I have already had a money offer to purchase them. I just have not decieded if I wanted to get into selling them.


1. How tight is the fit in the bore that accepts the tools.
I just used a standard drill for the size I wanted. After de-burring, the end mill slides into the hole and traps air inside. After about 5 seconds I can pull out the bit and get a POP! of air suction.


2. Do you preset your tool lengths, or just measure and store lengths in a tool file?
Right now I just clamp a bit in the holder and then use the CNC router to measure its length. Later I am thinking of placing a 'PIN' on the edge of the table and by moving the router over it can set the tools to a pre-set length.


3. Do you grind a flat on the side of the tool for the set screw?
I do grind a small mark in the side of the carbide bit.


4. Do you notice any vibration or out of balance conditions?
I have not seen or felt any vibration when using my holders. I have ran the router at all speeds and for long periods of time (7 hours with one tool). I'm going to say that I'm satisfied with my testing and am going to place my engineering stamp :) of approval on them.

:banana: :wee: :cheers:

lsfoils
07-05-2003, 09:49 PM
Hi all. This has been a very interesting thread. Good job Jeff. I too am in the throes of building (or at least aquiring parts for) a router. I seem to have found the right place!
Anyway, this topic is a couple of months old but I'll add my 2 cents in case someone finds it useful:
When trying to determine the angle of a collet, to reproduce the angle, set up your lathes headstock and tailstock with centers. Make sure your centers are somewhat accurate! Place the collet between centers. (If there is no "land" for the center to rest properly inside the collet you may have to make a close fitting mandrel with a center hole on one end which you can place into the collet with the center hole out). Next, place a dial indicator on the compound of your lathe and loosen the fasteners so the base will swivel. (Best to leave these a little tight so there is some friction during rotation) Dial tip goes onto the angle on the collet at center height and parallel to the bed and you start moving the compound slide back and for using its handwheel.
Change the angle of the compound with each pass so the needle on the indicator reads zero. By moving the compound back and forth along the length of the collet, the EXACT angle can be set on the compound. Then, just use the compound to turn a replica. Internal bores can be produced by placing the needle on the opposite side of the collet.
I hope this helps... -Doug

cbcnc
07-06-2003, 12:21 AM
Doug,

That is a good idea!
While you have the indicator on there you could roll the carraige and with a little trig figure the angle. If it is close to some even degree or whatever I would chalk it up to my inaccuracy and go with that.

Chris

lsfoils
07-06-2003, 02:01 AM
Chris,

Yep. But keep in mind that most manufacturers of collets, holders and taper lock tools in general don't use whole or evenly fractioned angles when deciding on the taper to use.... most of them use taper per running foot or taper per running inch. And even then they don't always use the same values from one size to the next. Morse tapers, from #0 through #8, are all over the place when measuring taper per inch. Brown and Sharp tapers are always .5" per foot except for their #10. (I guess they just had to be different)

Thats probably more than you wanted to know... Anyway, glad to hear someone found that post useful.

-Doug

HomeCNC
08-10-2003, 01:56 AM
I must have gotten the angle correct because when I go to loosen the collets they stick in the router and the nut needs to be turned against the snap ring to pop them free.

Carver
08-26-2003, 07:14 PM
Really nice job on the router and the project.
There is a never ending learning curve to what speed, tool, step-over etc. when cutting hardwoods. I have been carving with a cnc router full time for about three years now and still get surprises on a weekly basis. This was a really admirable first cut.

I have lurked here for quite a while before posting and have thouroughly enjoyed your project.

Good work,
Phill Pittman
digicarve@verizon.net
www.masterwerkes.com

rcrabb
08-27-2003, 07:39 AM
I believe Jeff still owes us a video. Anyone agree?

HomeCNC
08-27-2003, 11:25 AM
Thanks Phill.

Yes! Thank goodness for feed rate overide :)

Rcrabb, My cousin has filmed a cutting project but his digital editing PC has broken down. He is building a new one before he can finish my movie. I will let the group know when it's done.

HomeCNC
12-10-2003, 02:28 AM
Well I have my first video on my website. It is just a sample that my cousen Dan did to play with his editing software. It is not the finished one. This file is LARGE!! 48 meg. Only download it if you have high speed internet.

http://www.homecnc.info/router-movie.htm

kong
12-10-2003, 08:38 AM
Wow, awesome! Watching that machine cut is inspirational!
But...if your cousen doesn't mind me saying so, there were too many effects on the video and not enough routing, sorry! You can tell he know's what he's doing though!:D

*/kong has run away/*

HomeCNC
12-10-2003, 12:24 PM
I already told him that :) I said that it was fine for the introduction, but when the cutting starts to hold back on them. The next one he does will try to do that. What he want to do is make a video that is going very fast to show the work being done and bring the speed back to normal at key places. This way people can see the entire carving being done in a few minutes.

Also I told him that people like to see the motors and feed screws turning as well.
He is having fun! You know that the song in the introduction part of the movie is his creation. He is playing all the different instruments and put all the tracks together to create the song.

bcromwell
12-15-2003, 04:13 PM
Any new videos yet???

HomeCNC
12-15-2003, 11:04 PM
We just did another tape session on Sun of last week. 12/14/03

He is going to do another one.

balsaman
12-15-2003, 11:18 PM
I liked the first video but agree that the effects were somewhat annoying. A flashy intro is ok but then get down to business...:)

Eric

cncadmin
12-15-2003, 11:31 PM
What software did you use to make that video?

Mr.Chips
12-16-2003, 12:03 AM
Super Video!!!!!

I too would like to see more of the motors, shafts, belts, you know the meat and potatos of the business ends.

Hager

HomeCNC
12-16-2003, 12:20 PM
What software did you use to make that video?

I think he used Adobe Premiere Pro.

I'll let you all know when the next one is ready.

barbwirebi
12-18-2003, 02:12 PM
Jeff

Where did you get your Torid transformer?

Im looking for 36vdc 20amp minimum

Thanks
Bill
Bill

HomeCNC
12-30-2003, 05:26 PM
www.plitron.com

They have many to choose from. Just remember that you get two transformers in one toroid. So if you want 36VDC @20 amps purchase the 25VAC output at 10 amps. If you want 30 amps output get the 25VAC 15 amp toroid.

barbwirebi
01-06-2004, 10:25 AM
Thanks Jeff
I am considering "Pilitron PN# 117016201
with output of 25V @ 20 amp toroid

Will this be able to give me 36VDC @ 40 amps ?

I will be also running a simultanious 4th axis

Thanks so much
Bill

HomeCNC
01-06-2004, 02:42 PM
Yes in deed! Make sure you calculate the proper Capasitor for 40 amps. Oh I'll do it here.

40 amp * 80,000 / 36 VDC = 88888.88 so get a 90,000 uF cap.

keithorr
01-06-2004, 04:54 PM
.

HomeCNC
01-06-2004, 06:00 PM
I want to try my hand at a 4th axis on my router. Below is my CAD design. I'm going to make the spindle fit my 9X20 lathe chucks. The 6" bison is shown on the drawing. Of course it's servo powered. I'll use one of the 360 oz/in servo's I have.

HomeCNC
01-06-2004, 06:04 PM
I need to design the tail stock next. And then of course make the parts.

steveald
01-06-2004, 07:14 PM
Hi Jeff,

I like the 4th axis, unfortunately I have built my gantries too short. Maybe on machine #3 :)

I have a couple of questions for you.

I am looking at getting a Plitron 55VAC 13.64A transformer with dual outputs to run 2 servos. Is there an advantage to connecting the outs in parallel and having 2 drives share the 27.28A available? Or would it be better to use one output per drive? I was thinking that both outs in parallel would allow one drive access to any current not used by the other drive, and I don't think that would be true with one drive per output.

Also, with a servo rated at 1750rpm and 120V running at 77V, am I only limiting my speed? The way I understand it, the torque available is pretty much constant up to the rpm rating and dependant on the available current, and the available speed is dependant on the voltage of the P/S, so I should be able to run at approx 1100rpm with 77V. Am I on the right track here?

I want to use geckos, but if I need the 120V I will have to use Rutex, so I'm in a holding pattern trying to figure all this out. Any insight would be greatly appreciated.

Thanks

Steve

HomeCNC
01-07-2004, 01:39 AM
It is an advantage to connect the output in parallel. Think of the amps like a large pool of available power. All your servos will draw from this pool. If one servo is not using much that leaves more for other servos to use.

You should be fine at 77 VDC. You will never get the 1750 rpm of the servo motor anyway. Remember you will need to deliver steps from the PC to generate your speed. The servo can only go as fast as the step rate delivered to the drive. If you have a very low count encoder then you may be able to get the rated RPM but if you have a 250 - 500 count encoder then NO WAY!

steveald
01-07-2004, 05:37 AM
Hi Jeff,

Thanks for the reply.

Are you referring to 250 - 500 line encoders? The encoders on the motors I'm looking at are 500 line, quadrature 2000 count. Doesn't that mean that 35kHz pulse rate will move the servos max 1050rpm? (35,000 steps/sec * 60 sec)/2000 count = 1050

My mechanics work out to 2.286 revolutions of the motor per inch of travel, so 1050rpm will give me a max rapid of 459 ipm, which is what I'm looking for. Most of my work would be done with the motors spinning at 200rpm or so, and this is where I will need to have torque, am I missing something in my calcs, and are the speed/torque curves for servos basically flat from lets say 50rpm up to max rpm?

Sorry if I'm flogging a dead horse here, but I'm really new to servos and want to get this figured out before sinking another wheelbarrow of cash into it :) I really do appreciate the help.

Thanks,

Steve

HomeCNC
01-07-2004, 11:48 AM
You just answered your own question from before. You will not be able to get 1750 RPM. So you don't need to have a better power supply than your 77 VDC.

You must have a better PC than I have. I can't get 35kHz rate. I think I can get 25kHz.

You will have all the torque of the servo motors if you have enough amps in the pool of power we talked about.

You are fine with your thinking. Build away :D

barbwirebi
01-07-2004, 01:19 PM
Jeff

Thanks again for the power supply info.
As you stated in another post 36vdc @ 20 amps will be fine
for four 360 oz/in servos.

Your 4th axis looks great (what do you draw in?)
Are you building the bearing block/ holder & shaft to the cog gear?
Whats your planned ratio?

Thanks
Bill

steveald
01-07-2004, 03:43 PM
Thanks Jeff,

I guess what I was trying to figure out was if the lower voltage would affect available torque, and apparently it won't, so I feel a lot more confident about purchasing some of the parts. The PC I use is just a P3 - 866, but I have a Flashcut signal generator that takes the output from the Flashcut software and uses its own hardware to generate the step pulse stream. I really like it, but I think I'll try Mach2 on my new machine before investing in another Flashcut system.

Thanks again,

Steve

HomeCNC
01-07-2004, 04:49 PM
Your 4th axis looks great (what do you draw in?)

I use SolidWorks 2004


Are you building the bearing block/ holder & shaft to the cog gear?

If you look way back in this post to the very first one. You will see my CAD drawing of this router. Look at the spindle. At one time I was wanting to use a spindle and a DC motor so I could hold my R8 tooling. Well the spindle did not work out, so I'm using the bearing body for the 4th axis. I just need to make a new shaft that has the metric thread to accept my 9X20 chucks. The cog gear will bolt to the end of the shaft and squeeze the tapered bearings to hold everything together.


Whats your planned ratio?

It is 4:1 ratio.

daytrader
02-07-2004, 12:03 PM
Nice machine Jeff. Did you scratch build your table top, or did you find a source for T-slotted aluminum of that size? If so, what was your source?

What repeatability are you getting? How are you measuring it? Is there any racking of your gantry, especially when the router is not in its center?

I have read on McMaster's ball screw page that using ball screws requires a brake, in order to hold a position. Have you noticed any problems holding position?

Thanks.

HomeCNC
02-13-2004, 11:39 AM
Nice machine Jeff. Did you scratch build your table top

I did make the T slot table top from scratch. It was just aluminum bar stock that I milled a rabbit (woodworking term) on each edge. When two are bolted next to each other it forms a T slot.


What repeatability are you getting? How are you measuring it? Is there any racking of your gantry, especially when the router is not in its center?

I am getting repeatability as good as the rolled ball screw stock will give me. The spec is .004 per foot. That is much more than I need for cutting wood projects. There is no racking that I have noticed. I am glad that I did not make the gantry any higher than I did. I can tell on a deeper cut while doing the roughing that the router is flexing in the X direction just a small bit because the surface floor will show small height changes when passing back and forth.


I have read on McMaster's ball screw page that using ball screws requires a brake, in order to hold a position. Have you noticed any problems holding position?

I think what they are talking about is the Z axis might have a problem falling when the power is turned off of the servos or steppers. This can be a problem because a ball screw turns very easy and tends to have smaller TPI. I don't have this problem because of my 2:1 ratio. I have just enough mechanical advantage to hold my Z axis when the power is turned off from the servos.

xairflyer
02-13-2004, 06:44 PM
A RABBIT ???? is that another US term for a Rebate !!

Hobbiest
02-13-2004, 10:01 PM
Xairflyer,
A "rabbit" is a cut, usually made in wood joinery, that is like an upside down V. The router bit display at your hardware store would have them, no doubt. I think another term is dovetail, but not positive. Edit: come to think of it, I believe that a rabbit is simply a dado cut into the side of the wood, with a tenon running the full length of the piece to join it to. Look for a dovetail bit.

ballendo
02-13-2004, 10:12 PM
Originally posted by xairflyer
A RABBIT ???? is that another US term for a Rebate !!

Yes. Typically spelled Rabbet...

Hope this helps,

Ballendo

You say Cramps, we say clamps :D (and for us a rebate means money back!)

ballendo
02-13-2004, 10:18 PM
Originally posted by Hobbiest
Xairflyer,
A "rabbit" is a cut, usually made in wood joinery, that is like an upside down V. The router bit display at your hardware store would have them, no doubt. I think another term is dovetail, but not positive. Edit: come to think of it, I believe that a rabbit is simply a dado cut into the side of the wood, with a tenon running the full length of the piece to join it to. Look for a dovetail bit.

Hello,

A rabbet/rebate is usually 90 degrees, and is at the edge of the piece (has a bottom, and one "wall"). If it has two "walls", it's called a DADO, or PLough, or plow(latter two are older terms)

FWIW, you CAN have a rabbet with an angled "wall", made with a dovetail bit. This is used in cheap(or small) drawer construction sometimes. NOT to be confused with sliding dovetails, which have two "walls", OR with dovetails of the "pin and tails" variety...

Ballendo

xairflyer
02-14-2004, 04:30 PM
Like to see my rebate (rabbet) wood plane cut a V !!!!

A rebate for us is also money back, Cramps are something you get in your stomach after too much curry !!!!!

daytrader
02-14-2004, 07:06 PM
Originally posted by HomeCNC
I am getting repeatability as good as the rolled ball screw stock will give me. The spec is .004 per foot. That is much more than I need for cutting wood projects. There is no racking that I have noticed. I am glad that I did not make the gantry any higher than I did. I can tell on a deeper cut while doing the roughing that the router is flexing in the X direction just a small bit because the surface floor will show small height changes when passing back and forth.


Just because the "accuracy" of the lead screws is stated as .004in/foot does not mean that is what the "precision" or repeatability is. I think many people here do not know the distinction of the two terms.

Accuracy basically means how close the machine gets to the actual amount when it is instructed to move. For instance, if you tell the machine to move 1 inch, and it actually moves .990 inches, the machine's accuracy would be .010 per inch. Now, if you repeated this test a second time, and you got 1.010, you would average the .990 and 1.010 together, and get 1.000. If you did this 10 times and the average of all the numbers was 1.000, then the accuracy of the machine would be perfect for a 1 inch length.

Precision is different than accuracy. It is a measure of a machines ability to repeat to a location or a set distance. For instance, you tell the machine to move 1 inch and it moves 1.250 inches. However, you try this 10 times and each time it moved exactly 1.250 inches, it would have excellent precision.

The best machines will have excellent accuracy and precision. However, precision is the better measure of the quality of the machine. If the machine is precise, but not accurate, you can make adjustments through the electronics to adjust the machine. If the machine is not precise, that means the improvement must be made to the structure of the machine and its design.

Another way to visualize it is with a dart board. If one player aims for the bulls-eye and makes a perfect circle of 5 inches around it with 10 darts, his accuracy would be excellent, because the average of all 10 darts is the exact bulls-eye. However, his precision would be poor, because the darts were 5 inches from the target. If on the other hand, the player aims for the bulls-eye and hits a spot 10 inches from the target, but all 10 darts hit the exact same spot, his precision would be excellent, and his accuracy poor. Finally, if all 10 darts hit the exact bulls-eye, both his precision and accuracy would be excellent.

I think the only way to reliably measure the precision of a machine is using indicators. One thing you can do is mount an indicator in the spindle, and then zero it against a 123 block (or something similar) clamped to the table. Also zero the x, y, z from the controller. Then, move the spindle to several arbitrary places along the table. Finally, return the spindle to 0,0,0 and see if the indicator also reads 0. Repeat this several times, and approach the origin from several directions, to determine how precise the machine actually is.

To measure the accuracy, you will need a precision ground block that you know the length of (a 123 block is fine). Pick up the edge of the block using an indicator mounted in the spindle, then instruct the machine to move the length of the block, pick up the other edge of the block with the indicator, and see if the indicator still zero's out. If it does, that means the machine moved the exact amount. If it does not, the amount it is off is the accuracy of the machine for that length.

One way to measure the racking of the gantry might be to place a dial indicator on each side of the machine's frame, so that the plungers touch each side of the gantry. Zero out the indicators. Then tell the machine to hold its current position and turn on the router. Feed a piece of wood freehand (carefully of course) under the spinning cutter, at a similar rate that the machine moves at. This should simulate the cutting forces the machine normally experiences. Have someone else look at the two indicators to see how much they moved while you were feeding the wood. Repeat the same test with the router in the middle of the gantry, and at different places along its length. I suspect the racking would probably be least when the router is in the center. You can also repeat the tests feeding the wood from different angles and from different sides of the cutter. You can also mount the indicators so that they show the relative movement between the z axis and the gantry.

I realize for woodworking these numbers aren't that important. But as your machine seemed to be one of the more sturdy ones, I was curious as to its actual measured performance.

Thanks

turmite
02-15-2004, 12:32 AM
"Another way to visualize it is with a dart board. If one player aims for the bulls-eye and makes a perfect circle of 5 inches around it with 10 darts, his accuracy would be excellent, because the average of all 10 darts is the exact bulls-eye. However, his precision would be poor, because the darts were 5 inches from the target. If on the other hand, the player aims for the bulls-eye and hits a spot 10 inches from the target, but all 10 darts hit the exact same spot, his precision would be excellent, and his accuracy poor. Finally, if all 10 darts hit the exact bulls-eye, both his precision and accuracy would be excellent"

Daytrader I can tell already that you don't shoot competition benchrest rifles :D cause if you did and you shot those kind of groups it typically is referred to as "******" well being that I don't use course language you will have to fill in the blanks!:D

Seriously though I may be one of those that thought repeatability meant something else. In my machine which was the first "kit" cnc machine offered for sale in the US repeatability meant being able to make the same part for a 1000 parts and they would all fit. My machine uses rack and pinion which most people seem to frown on but I can drill hole anywhere on the table which is 60"X120" run the machine all day and go back the next day run the same program to drill that hole and it won't even fuzz the edges. On the other hand since this machine is so large and made of aluminum rectangular tubing it flexes and vibrates like crazy even when making shallow cuts.

I am sincere when I ask this. Is that repeatability or accuracy?

There are advantages to working with wood.

Mike

turmite
02-15-2004, 12:37 AM
Oh yes, Jeff I am in the middle of rebuilding one of the 3 1/4 hp Porter Cable routers I have and had to take the threaded end off of the shaft to get to the bearing. Well I found it wont be much of a problem to make a new nut with the capacity for one of your neat toolholders for 1/2" bit. I have to make sure I get the angle right then I will send you the cad file if you want it.

Mike

Mr.Chips
02-15-2004, 12:56 AM
Daytrader.

Good example...

For thoes of us with movable tables, mounting an indicator on an non CNC machine surface and indicate each side of the gantry then run the machine in the "X" axis directions. This would indicate how much gantry flex there was. Naturally this would vary with speed, depth of cut, tool condition. . .

I would like to see a standard test method written for testing and comparing machines. Whats good for one person may not be so good for another.

Thanks
Hager

daytrader
02-15-2004, 01:06 AM
Mike,

If your machine can make many parts that come out the same, then it is a precise or repeatable machine. You can use those two terms interchangeably. Comparing parts is probably a good way to measure precision because it takes into account any flexing of the machine only experienced while cutting. It also does not require a lot of indicators.

Now, if your holes were programed to be 10 inches apart, and you measured the actual holes to be 10 inches apart, your machine would also be accurate.

The reason I brought all this up is because the machine I am going to build will be used for inlay cutting in pool cues. This will require a precision of .001 inch I estimate, so that there will be no visible gaps between the inlays and the surrounding structure.

turmite
02-15-2004, 01:25 AM
daytrader I hope you didn't think I was trying to flame you. I really have been calling it repeatability and just wanted to know if I had been calling it the right term.

I don't know if you make cues yet or not but there is another sure way to get good inlays and especially with a cnc. When doing your cut in the wood and the inlay material use a tapered cutter on both but cut trhe inlay from the back side. This is a spin of the way old time gunsmiths did their intricate brass work on the old flint and percussion black powder rifles. Some of those things are pure art. Basically they put a draft on the pieces and the wood.

What kind of controller are you going to use?

Mike

daytrader
02-15-2004, 01:45 AM
Turmite,

I didn't think you weren't flaming me, and found your post amusing.

I have been doing cue repair work for about 5 years, but have yet to build one from scratch, mainly because I can't cut the "curved taper" required for the front half of the cue (the shaft) without making a curved taper bar for my lathe. The problem with that is that it would require a different bar for each taper I desired. I figured by building a cnc machine, I could make any taper I desired, plus do the inlay work.

I just got all the linear bearings and rails from ebay and will design the machine around them, and hopefully start building in about one month. I'm going to initially try EMC as the software. If I can't get it to work (I'm not a linux user) I will try Mach 2.

daytrader
02-15-2004, 01:47 AM
Oh, and the beveled edge is a great tip. Thanks. The only thing that worries me about it is the possibility of a gap on the bottom side of the inlay.

arvidb
02-15-2004, 05:35 PM
Originally posted by daytrader
Mike,

If your machine can make many parts that come out the same, then it is a precise or repeatable machine. *snip*

Is the fact that a machine can make many parts that come out the same really enough to call it precise?

Wouldn't precision (or repeatability) also require that the parts would come out the same no matter in what order you made the cuts?

I.e. if you did the whole cutting backwards and the part still comes out the same, *then* you have a machine with high precision/good repeatability?

Arvid

turmite
02-15-2004, 10:52 PM
Arvidb I know that your test might be fine for metal working machines but for the most part the wood machines don't have to have that kind of accuracy/precision/repeatability. Now daytrader see what you started! I don't even know what to call it!:D

When I first started my business I though I needed .001 or better but found out pretty quick that most of the parts I was fitting to had quite a bit more tolerence than that. I really have found that all I need is .010 to .020 accuracy or precision but I need the machine to do the same program the same way every time. I actually have ran a few of the programs backwards to try to stop tearout and the fit was the same.

In the case of inlay I am quite sure the folks doing that with cnc was as good of accuracy/precision/repeatability due to the high cost of the inlay material.

daytrader I have just retrofitted to Mach2 and so far love it. I know nothing of linux so keep us posted.

Mike

steveald
02-15-2004, 11:49 PM
Hi,

If you can cut a part that your customer will write a cheque for, then you have an accurate machine, if your customer comes back for more, then it is repeatable. :) Just kidding.

I would also like to see a standard suite of measurements to compare machines, the specs for the machine I use at work list cutting accuracy as 0.000079" resolved. It's useless info, my homebuilt machine has 0.0001" accuracy resolved, if I change a jumper on my driver it has 0.000004" resolved. It doesn't make any difference to the final product though, they're just empty numbers for salesmen to wave about.

I haven't done any measuring on my machine, other than looking at the difference between old zero and new zero when I home the machine. Since I installed larger motors, it is always less than +/- 0.001. Even that info is basically useless, as it doesn't take backlash, non-linearity of microsteps, gantry deflection, tool run-out etc... ad infinitum into account.

I think what I will try is to cut a series of 4" x 3" rectangles each rotated 15 degrees more than the last, placed randomly about my table. That will allow me to check for square as well. They should measure 5" diagonally. I'll have to think about how to interpolate the results. Any suggestions?

Steve

arvidb
02-16-2004, 03:24 AM
Originally posted by steveald
Hi,

If you can cut a part that your customer will write a cheque for, then you have an accurate machine, if your customer comes back for more, then it is repeatable. :) Just kidding.

LOL :)

Have you noticed that if you select a happy smiley (by dragging your mouse pointer over it), it suddenly gets very depressed? Or mean, depending on it's position on the screen. Hehe.

Arvid

ballendo
02-16-2004, 08:54 PM
Hello,

Gotta jump in on this one. several of my "favorite" topics being discussed:)

Resolution, repeatability, accuracy, and precision are all different things. And they all share the distinction of being widely misused...

Daytrader got most of it right, but I'd add that repeatability and precision are NOT interchangable terms.

Repeatability means just what it sounds like; every time you specify a location, you go to EXACTLY The same spot. The amount that a given machine varies from this ideal is it's repeatability.

Precision implies (requires) accuracy as WELL as repeatability. You can look it up and see that precision is minimal variation about a "set standard"- And working to a standard (and attainment of it) is accuracy. You don't have precision without accuracy.

And now we have to go one deeper, and define TWO types of accuracy... Relational and absolute.

Absolute accuracy is unchanging, and is what manufacturing is based on nowadays. That is to say, an inch is the same length everywhere, always. As is a millimeter. There are "standards" kept to ensure that this is so. Companies working to high levels of precision (there's that word again:)) will have calibration items which are traceable to these nationally held (and internationally held) standards, of length, mass, etc. In the USA, the National Institute of Standards and Technology (NIST) is the keeper of the standards.

Many of us in the DIY-CNC community don't need to attain this level of accuracy. We are content to trust our purchased indicators and dial calipers. Which works well, due to the nature of the second, FAR MORE LIKELY type of accuracy; which is relational. This is how well items fit in the way that they are supposed to.

A previous post mentioned old gunsmith work, and called it accurate. You can bet this is relational (also called relative) accuracy. The parts fit each other, even though they may not be absolutely accurate dimensionally (according to a drawing or intention). In relative accuracy, the unchanging "standard" above is replaced with one or more "related" standards. For a nut, it can be screw, for an inlay, a recess; and for a diy-cnc'r it can be that chinese dial caliper:D The point is that if the parts fit, we CAN say they are acurately made. Or that they fit with great precision. (like the stone blocks of the pyramids)

Anyway, it's a good thing that relative accuracy is so suitable for so many things, because getting TRUE absolute acccuracy is pretty Durn difficult. Which brings me to my pet peeve of DIY-CNC.

Which is the confusion of resolution, with accuracy. The thought that since "my drives are microstepping to .0001, then my machine is capable of that too!" Sheer lunacy; and ever present...

If you want to have some fun, get a pad of graph paper. Now draw circles--using a compass-- and squares(not on the lines!) , and even arbitrary curves. NOW...

"Trace" the things you have drawn, BUT! you can only draw using the points where the graph lines meet--the corners of each square. So each move of your pen will be up, down left right, or diagonal, across ONE square. Then you do it again. See how far away from ACCURATE you are!?!? Now consider that each square represents one step of your motors (or the distance of one count of your encoders in the case of servos)...

Next, work out what it would "look like" to make a 9/32 hole with a 1/4 inch cutter (If your machine has steps of .001, you're going to make a "circle" with 32x32 squares. Try it. (And DON'T line the circle up with the graph lines...)

I know what you're thinking. "But my machine has .000125" steps. No, it doesn't. The structure, motor and dynamics of motion will "eat up" most of this "resolution". Leaving far less REAL resolution. We call it "empty" resolution. It's the amount your stepper--microstepping, even-- "lags" before the forces build up enough to overcome the inertia, and stiction, etc...

Bottom line is this. Turmite got it right, IMO; when he said, "I thought I was gonna need .001, but I don't..." Once you consider the above, and add things like abbe errors, cyclic and periodic screw inaccuracies, thermal effects on both motion components and structure you are left with the TRUTH.

Which is: Resolution is easiest to claim, but generally mostly meaningless--depends how it's obtained, if by using microstepping or step-servos, you really don;t have what you "think" you do!-. Reasonable repeatability IS attainable. Whic is a good thing. because "accuracy" is not likely. At least the absolute kind. Relative accuracy, as Daytrader said, IS the "child" of repeatability. It's like that archer who had the nice group 10 inches off target (but all together,see the ps for a disagreement with DT); he or she can "dial in" the sight, and attain accuracy when repeatability is present. Just don't expect to get it "direct from quiver-dual meaning intended:)

Ballendo

P.S. I waited to reply to this because it's a toughie; a matter of scale... But I do NOT agree that if your machine is .990 one time, and 1.010 the next, and it contines to "average" around 1.0000, that it is accurate. OR repeatable! Or precise. And if the arrows are all around the bullseye, and 5 inches away, can we call this an "average" bullseye?!?! (If that's the way the game is played, I'm gonna take up darts:D) Because when we take this to its natural progression, such a definition means that everything is accurate, because over time the likelihood of the errors averaging out gets better and better!

But I don't think you're gonna find a customer who accepts parts that are too small, because "next time" they'll be "too big"!!

"No really ma'am, we're very accurate. It just takes time..." :p


(But the reason I saved it for last is that IF the "squares" are small enough--certainly not the .010, or the 5 inches of the examples given-- but IF we "look at it" from a "bigger" view, he's right... Because on some level, we're ALWAYS all over the bullseye without touching it...) But I don't think the example is a good one, if you're trying to get across the idea of resolution, repeatability, accuracy, and precision.)

ballendo
02-16-2004, 09:03 PM
Steve,

Excellent post! As for the rectangles--A good idea, and a fair test of a machine's overall ability-- be sure to begin and end the cut for each in the middle of a SIDE, NOT at the corners (bacause you're planning to use the hypotenuse, and cutter deflection upon entry will really skew the results!

Ballendo

P.S. Even the kidding part is good. Because that IS the real world litmus test of whether you and/or your machine is doing what it's supposed to... (The proof is in the parts)


Originally posted by steveald
Hi,

If you can cut a part that your customer will write a cheque for, then you have an accurate machine, if your customer comes back for more, then it is repeatable. :) Just kidding.

I would also like to see a standard suite of measurements to compare machines, the specs for the machine I use at work list cutting accuracy as 0.000079" resolved. It's useless info, my homebuilt machine has 0.0001" accuracy resolved, if I change a jumper on my driver it has 0.000004" resolved. It doesn't make any difference to the final product though, they're just empty numbers for salesmen to wave about.

I haven't done any measuring on my machine, other than looking at the difference between old zero and new zero when I home the machine. Since I installed larger motors, it is always less than +/- 0.001. Even that info is basically useless, as it doesn't take backlash, non-linearity of microsteps, gantry deflection, tool run-out etc... ad infinitum into account.

I think what I will try is to cut a series of 4" x 3" rectangles each rotated 15 degrees more than the last, placed randomly about my table. That will allow me to check for square as well. They should measure 5" diagonally. I'll have to think about how to interpolate the results. Any suggestions?

Steve

arvidb
02-17-2004, 05:00 AM
Originally posted by ballendo
Hello,

Gotta jump in on this one. several of my "favorite" topics being discussed:) *snip*

Great post ballendo! I'll print this one out.

Arvid

Mr.Chips
02-17-2004, 09:21 AM
Good job Ballendo.

Wish this forum had a place to put "Best" practices, tests, examples. . . .

There is so much very good information that is here and it will be lost to many new people that come along later.

Hager

High Seas
02-17-2004, 09:43 AM
"Great post ballendo! I'll print this one out.", Arvid

"Wish this forum had a place to put "Best" practices, tests, examples...", Hager

Sorry, I missed yours ballendo - but its a good one! Terminology can be very confusing and misleading for the uninitiated; and this site has a lot of uninitiated and plain old NEWBIES - like yours truely. Too bad its only Just In Time application and not in the Technical Articles section. That would be a great follow-up. I especially liked your use of the holesaw approach.

Guess I was just lucky enuf to be working the same "thread" -- but offline -- as a tech article! I was getting bugged by the lack of precise usage of a few terms as well. Had to do my research to get them right- don cha know. Hager - I was cleaning up my RANT here while you were writing too! :cool:

But most importantly, it shows we have some real sharp cookies out here that could put some real basic, important, meaty articles in that FAIRLY EMPTY TECHNICAL ARTICLES SECTION. And folks that would read it -- and print it out too. It seems a whole lot easier to look for those kinds of definitions in the Technical Articles than in a discussion that has covered: rabbits, rebates, SW, choice of bits and pieces, etc in a homebuilt CNC thread that has over 146 replies and over 16,700 views! :drowning:

But folks, we are all responsible for this - Its too easy to fop it off to the moderator and say - "not my job", or putting in all those "funny <b> </br> is too much b... If we hide all the nuggets we discover from hours of experience, trial and error, research, and endless threads, we perpetuate ignorance. This is a slipery slope - I've said that before. I think the 'Zone could use a Tech Writing Team. Guess we're all part of it - but need some focus.
This is at least my second RANT on this topic - maybe I should have my own corner - oh look I do - guess I'll go sit in it for a while. :mad:

Back to the earlier avitar questions - the dragon just came out again!

- no cheers - Jim

pack rat
02-17-2004, 10:11 AM
ABSOLUTELLY ACCURATE post ballendo, thank you for showing me the light. These posts should be saved and displayed in some kind FAQ for everybody to read. It has fundamental importance. I know I'll have to read it few times till I get it right. I hope I can remember where is at. :rolleyes:

HomeCNC
02-17-2004, 12:06 PM
Well, After all this, to answer daytraders question #126

I havent got a clue :D It just works for me!

daytrader
02-17-2004, 08:41 PM
Wow. One innocent question and all this:)

Ballendo, I am fairly confident that precision and accuracy are completely separate measures, with neither having any dependancies on the other. I will research it further.

I'm glad we all got this topic out in the open, however.

ballendo
02-18-2004, 10:23 AM
Hello,

From dictionary.com:

pre·ci·sion ( P ) Pronunciation Key (pr-szhn)
n.
1.The state or quality of being precise; exactness.

2.The ability of a measurement to be consistently reproduced.
3.The number of significant digits to which a value has been reliably measured.

And from the online webster's dictionary:

One entry found for precise.

Main Entry: pre·cise
Pronunciation: pri-'sIs
Function: adjective
Etymology: Middle English, from Middle French precis, from Latin praecisus, past participle of praecidere to cut off, from prae- + caedere to cut
1 : exactly or sharply defined or stated
2 : minutely exact
3 : strictly conforming to a pattern, standard, or convention
4 : distinguished from every other <at just that precise moment>
synonym see CORRECT
- pre·cise·ness noun

adj.
Used or intended for accurate or exact measurement: a precision tool.
Made so as to vary minimally from a set standard: precision components.
Of or characterized by accurate action: precision bombing.
--------------------------------------------------------------------------------
[Latin praecsi, praecsin-, a cutting off, from praecsus, past participle of praecdere, to cut off. See precise.]

Hope this helps,

Ballendo

Builder4wd
02-20-2004, 06:47 AM
Hi,

I thought I'd add something from my Numerical Methods and Engineering textbook (4th edition, by Chapra and Canale):

---
Accuracy refers to how closely a computed or measured value agrees with the true value. Precision refers to how closely individual computed or measured values agree with each other.

Inaccruacy (also called bias) is defined as systematic deviation from the truth.

Imprecision (also called uncertainty), on the other hand, refers to the magnitude of the scatter.
---


The diagram in the book shows four bullseye targets:

a) bullet holes scattered far apart and away from bullseye in the upper left hand corner.
-> inaccurate and imprecise

b) bullet holes scattered far apart around the bullseye.
-> accurate and imprecise

c) bullet holes grouped closely together, away from the bullseye in the upper left hand corner.
-> inaccurate and precise

d) bullet holes grouped closely together, on the bullseye.
-> accurate and precise



Although the shots in c) are more tightly grouped than those in a), the two cases are equally biased because they are both centered on the upper left corner of the target.

Although b) and d) are equally accurate (that is, centered on the bull's-eye), the latter is more precise because the shots are tightly grouped.


So my understanding, from this textbook, is that precision and accuracy are independent. They can probably be used interchangeably in everyday language, but if you want to get specific they are separate entities.

Hope this helps!

ballendo
02-20-2004, 08:20 AM
Hello,

I think you misinterpreted in your summary, based only on what you've written...

First statement says accuracy is based on a "truth". Agreed.

Next statement says precision is repeatability. Also agreed. (But it's more than JUST that. This statement is correct as a subset of the meaning)

Third statement says bias/ inaccuracy is departing from "truth". Agreed.

Fourth statement says degree of precision is characterised by the amount of variation. same as 2nd above. Agreed.

Then to your target pics: I agree with a and d.

B, on the other hand, cannot be called accurate, if the hits are scattered. Look again at the statements above. Accuracy is based on truth. Where is the truth in a scattering of hits? (unless you're running for office<G>) We're back to the idea that somehow you can call "averaged" part locations accurate. So again I'll say; are you gonna tell your customer, "Sure these holes are all too small. But the next batch will all be too big. So it all evens out, and our shop IS accurate!" :confused: You've gotta be kidding... (tolerances is a whole other ballgame, best left out of this discussion to preserve clarity.)

The example C seems to support what daytrader said. That precision is repeatability ONLY. I agree, but only when we're dealing with relative accuracy. In other words, an 18th century gunsmith made parts which had good fit to each other, but would fit no other gun as well, except by "accident". So the work was precise, as it was working to the TRUTH of the OTHER part(s). They were the "standard"--which must be present for precision to have any meaning.

Read again the definitions I provided... What is exactness, except adherance to some "measured" value? And the second def. goes even further to dispel misunderstanding as it uses "Measured" IN the def. But the kicker is def 3, where we're measuring to sig. digits. But these latter two still only allow for precision to be repeatability. So we go to webster's, which in def.3 sez, "strictly conforming to a pattern, standard, or convention" What is the pattern standard or convention? It is EITHER the other parts--relative accuracy, OR the basic "truth", which defines the link between precision and accuracy... You cannot have precision without some adherence to some standard of Accuracy.

Let me ask it another way, Are repeatability and precision the same thing? If I'm making donuts using a computer controlled dough dispenser, they surely are repeatable... But are they precision donuts, because they all contain the same amount of dough? (Most commercial food processors have some "standard" by which their products are evaluated. You can see the pictures of food the cooks use sometimes at restaurants. What will it take for us to say a given item is made with precision?) It's not enough to just be repeatable; it must be repeatable to some pattern, standard, or convention... (according to Webster)

Now to your second conclusion: "Although b) and d) are equally accurate (that is, centered on the bull's-eye), the latter is more precise because the shots are tightly grouped."

This is exactly what I said. Precision is repeatability AT the truth "aimed for"... And "truth" in this case, is accuracy.

Ballendo

P.S. What is the definition of precision given in the glossary of that book?

High Seas
02-20-2004, 09:45 AM
Accuracy: You shoot -- and you hit what you're aiming at.

Repeatability: Everytime you shoot - you hit the same thing. This may (or may not) be what you were aiming at. Now, draw a circle around all the hits, you will use in a moment. Call this "the circle of repeatability."

Resolution: As close as you can get, with what you're shooting. Remember, close only counts in horseshoes, hand grenades, cluster munitions, and 'nukes.

Precision: How close you are to hitting the same thing -- each time you shoot. The size of circle of repeatability defines your precision.


Relatedness: The smaller the value of Precision, the smaller the "scatter", or the tighter "the grouping." The better the Precision, the easier to adjust for "bias" and make adjustments to improve Accuracy. Unfortunately it can't get any better than the established Resolution.

SO WHAT?: For making adjustments, you could best start by first knowing the system's RESOLUTION. Then, measure REPEATABILITY -- draw the circle. Next, describe the system's PRECISION. Then adjust the system to improve system ACCURACY.
In weapons development/deployment - we used CEP as a descriptor of precision - another time - another place - a different life.

Builder4wd
02-20-2004, 05:02 PM
Ballendo,


Originally posted by Builder4wd


The diagram in the book shows four bullseye targets:

a) bullet holes scattered far apart and away from bullseye in the upper left hand corner.
-> inaccurate and imprecise

b) bullet holes scattered far apart around the bullseye.
-> accurate and imprecise

c) bullet holes grouped closely together, away from the bullseye in the upper left hand corner.
-> inaccurate and precise

d) bullet holes grouped closely together, on the bullseye.
-> accurate and precise


Although the shots in c) are more tightly grouped than those in a), the two cases are equally biased because they are both centered on the upper left corner of the target.

Although b) and d) are equally accurate (that is, centered on the bull's-eye), the latter is more precise because the shots are tightly grouped.



Actually all this is from the book, only in the book there are actual diagrams so I added the description of the diagrams. The conclusions are not mine, they're from the book.



Originally posted by ballendo

...

Next statement says precision is repeatability. Also agreed. (But it's more than JUST that. This statement is correct as a subset of the meaning)

...

B, on the other hand, cannot be called accurate, if the hits are scattered. Look again at the statements above. Accuracy is based on truth. Where is the truth in a scattering of hits? (unless you're running for office<G>) We're back to the idea that somehow you can call "averaged" part locations accurate. So again I'll say; are you gonna tell your customer, "Sure these holes are all too small. But the next batch will all be too big. So it all evens out, and our shop IS accurate!" :confused: You've gotta be kidding... (tolerances is a whole other ballgame, best left out of this discussion to preserve clarity.)

Read again the definitions I provided... What is exactness, except adherance to some "measured" value? And the second def. goes even further to dispel misunderstanding as it uses "Measured" IN the def. But the kicker is def 3, where we're measuring to sig. digits. But these latter two still , or convention" What is the pattern standard or convention? It is EITHER the other parts--relative accuracy, OR the basic "truth", which defines the link between precision and accuracy... You cannot have precision without some adherence to some standard of Accuracy.

Let me ask it another way, Are repeatability and precision the same thing? If I'm making donuts using a computer controlled dough dispenser, they surely are repeatable... But are they precision donuts, because they all contain the same amount of dough? (Most commercial food processors have some "standard" by which their products are evaluated. You can see the pictures of food the cooks use sometimes at restaurants. What will it take for us to say a given item is made with precision?) It's not enough to just be repeatable; it must be repeatable to some pattern, standard, or convention... (according to Webster)

Now to your second conclusion: "Although b) and d) are equally accurate (that is, centered on the bull's-eye), the latter is more precise because the shots are tightly grouped."

This is exactly what I said. Precision is repeatability AT the truth "aimed for"... And "truth" in this case, is accuracy.

Ballendo

P.S. What is the definition of precision given in the glossary of that book?


I've already posted the definition in the book :
"Accuracy refers to how closely a computed or measured value agrees with the true value. Precision refers to how closely individual computed or measured values agree with each other."


I found some websites that seem to be in line with my textbook:

http://www.ece.unb.ca/tervo/ee2791/intro.htm

"Note that an accurate instrument is not necessarily precise, and instruments are often precise but far from accurate. "

these have bullseye pictures:

http://www.mhhe.com/physsci/chemistry/chang7/esp/folder_structure/ch/m2/s2/

http://elchem.kaist.ac.kr/vt/chem-ed/data/acc-prec.htm

http://www.higp.hawaii.edu/~cecily/courses/gg313/DA_book/node10.html


Basically accuracy and precision are independent. It's a misconception that one would imply the other. I think Webster's definition is fine for everyday language, but when you're doing scientific measurements, accuracy and precision are different and not interchangeable. I would say the definition you found on Webster's is very precise, but not accurate. :)

pminmo
02-20-2004, 06:46 PM
Accuracy is exactness, the ability to measure or produce an actual value verses the expected value. 3 arrows far from the bullseye but close to each other is not definable by itself, but it is definitely inaccurate. Repeatablility is the ability to predict the outcome of an event based on prior same events. Different from accuracy or precision. Absolute accuracy is the measured values verses expected value, differential accuracy is how accurate the differential value is. You tell a cnc machine to move 1" and it moves 1 inch regrdless of where it is on it's x y axis. It has good differential accuracy,but there is no absolute accuracy that can be derived because there is no absolute reference made. you tell it to go to 1" x and 1" y from the origin and it hits 1"x and 1" y dead on and it has excellent absolute accuracy, still cant say it's precise or not. Resolution and precision are close. Your cnc machine finest step is .05 inches. You tell it to move to absolute position 1.000x 1.000 y and it does, you think you have absolute accuracy. You tell the same machine to go to 1.005 and it goes to 1.000 because it cant resolve finer than .05 its not so precise after all.

Phil

ballendo
02-21-2004, 04:03 AM
Hello

Well, it appears that the engineering books support the idea that repeatability and precision are the same thing. Which I agree with. But they also seem to support the idea that precison and accuracy are unrelated...

So I find myself in the position of daytrader a few messages back.
I'll need to look into this further. It appears that I'm wrong.

It ALSO appears that the engineering sites and texts consider accuracy to be only an average...

For this I can only recall growing up with a Father who used to gripe that "them eng'neers got no idea whats goin' on in the real world!"

Because I'm still laughing with the thought that I've brought up a few times now... "Inaccurate because they're too big?!? Of course they're accurate, once we make next weeks batch, all undersize!"

Ballendo (1 for 2)

arvidb
02-21-2004, 08:09 AM
Just a thought:

Can't it be that you say a machine is accurate but have lousy repeatability if you hit all around the bullseye, but...

if you make ONE measurement (on a produced part, for instance), you can't say it's accurate unless it conforms to the standards (i.e. would require an accurate machine and either luck or good repeatability)?

From pminmo's post above it would also follow that you cannot have a precise machine unless it has high resolution and a repeatability good enough to make the resolution useful.

What do you say?

Arvid

pminmo
02-21-2004, 09:41 AM
Originally posted by ballendo
Hello

Well, it appears that the engineering books support the idea that repeatability and precision are the same thing. Which I agree with. But they also seem to support the idea that precison and accuracy are unrelated...

It ALSO appears that the engineering sites and texts consider accuracy to be only an average...

For this I can only recall growing up with a Father who used to gripe that "them eng'neers got no idea whats goin' on in the real world!"

Ballendo (1 for 2)

My education and years of professional experience is in electronics so I may have a slightly different slant. A 3 digit voltmeter isn't considered a precision intrument, an 8 digit is. But as to precision and repeatability the same I have to disagree with the engineering books (even though I am one). Exaguration here to make my point, a stepper that has 20 steps per revolution driving a 2tpi screw gives you a resolution of .025, if that screw is perfect i.e. +/- .00000 and the motor is perfect you have a drive that is very repeatable, i.e. you tell it to go to any position that is evenly divisable by .025 and it does every time. Now try to make a part that has geometry defined to .0005, that perfect repeatability doesn't do you an ounce of good because the machine lacks the precision to do it.
"Accuracy being only and average" maybe out of context. Two lines seperated 1.000 inch, One instrument make measurements of 1.5", 1" and .5", an average to 1", but the instrument used to make those three measurements can't be considered accurate. A instrument that makes three measurements to .99990, 1.00010, 1.0000 is accurate. Accuracy is the ability to measure or produce expected values verses actual values, nothing else, not even debatable. That is why we have the NBS, and why calibration laboratories have instrumentation tracable to NBS.

Phil

High Seas
02-21-2004, 11:00 AM
Let me try this one step at a time.

Originally from pminmo:
QUOTE: Now try to make a part that has geometry defined to .0005, that perfect repeatability doesn't do you an ounce of good because the machine lacks the precision to do it. UNQUOTE.

Sorry, but the machine you described lacks the RESOLUTION to mill to 0.0005. As good as it gets is defined by the limitations you built in: the stepper and the drive. You can only make assumptions regarding the machine's REPEATABILITY -- until you actually make the part, many parts, and see how close they are to each other. it won't be worth a hoot if its not the size you need for the job or customer - and a lot of scrap lying around too. Milling within our limitations or making adjustments is what we'd be forced to do with such a machine. But clearly that machine lacks the RESOLUTION to do the requested job. If all those scrap parts are the same dimensions, then we'd have good repeatability, within our system resolution - but only when compared to the desired output can we make statements regarding precision and accuracy.


ACCURACY is the ability to get the expected result. To hit what you aim at, to measure the gap with as many significant digits as the ruler has, to set or measure the resistance to the --CORRECT - expected value. Any error, deviation, scatter, bias, or miss of the measured result from the EXPECTED (read - correct) value describes the precision. NOT the number of digits in the meter. More digits increase the ability to make greater descrimination in our measurement. Measuring to 8 significant digits often implies PRECISION (and sometimes ACCURACY). But the additional digits provide only some confidence - if we've calibrate as Phil suggests (thats what we always do righto?).

pminmo
02-21-2004, 01:15 PM
Originally posted by High Seas
Let me try this one step at a time.

Originally from pminmo:
QUOTE: Now try to make a part that has geometry defined to .0005, that perfect repeatability doesn't do you an ounce of good because the machine lacks the precision to do it. UNQUOTE.

Sorry, but the machine you described lacks the RESOLUTION to mill to 0.0005. As good as it gets is defined by the limitations you built in: the stepper and the drive. You can only make assumptions regarding the machine's REPEATABILITY -- until you actually make the part, many parts, and see how close they are to each other. it won't be worth a hoot if its not the size you need for the job or customer - and a lot of scrap lying around too.


ACCURACY is the ability to get the expected result. To hit what you aim at, to measure the gap with as many significant digits as the ruler has, to set or measure the resistance to the --CORRECT - expected value. Any error, deviation, scatter, bias, or miss of the measured result from the EXPECTED (read - correct) value describes the precision. NOT the number of digits in the meter. More digits increase the ability to make greater descrimination in our measurement. Measuring to 8 significant digits often implies PRECISION (and sometimes ACCURACY). But the additional digits provide only some confidence - if we've calibrate as Phil suggests (thats what we always do righto?).

I understand and completely agree on the resolution, it was precisely :-) my point. Also agree on part of the repeatability you state. The theoritical machine I described will make a perfect repeatable part if the part has geometry defined in .025 increments. So if the part has four holes spaced 1" apart, you will have perfect repeatability. now if those holes are spaced 1.0125 apart, the parts will vary because the being eactly at half the resolution the computation will sometimes go .0125 strong, sometimes .0125 weak. Repeatablilty and precision are related but different animals. If I buy a ball screw that over the length is accurate to .00001 any place on the screw, .00001 backlash on the nut, and the stepper steps are accurate to .00001 degree, I can make a calulated determination on repeatabilty when it is designed. Maybe this helps, before we did anything digital i.e. in a purely analog world, there is no such thing as resolution because the resolution is infinity in theory in a purely analog sense. Just because you have infinite resolution, no statement can be made on precision.
Completely agree on your accuracy statement---
Maybe the elctronics world has different slant on things and I'm to thick headed to see it any other way. :-)

Phil

ballendo
02-21-2004, 06:46 PM
Hello,

I'm pretty sure we're all on the same page regarding accuracy, and what it means. I think we also all agree on repeatability and resolution. It's this "precision" thing that's befuddling to some of us...

I've been thinking hard about this over the last few days...

And I think I've got it settled in my mind at least:)

Repeatability and precision are a subset, or precursor of accuracy.

If you have either, you also have accuracy. It may not be the dimension you want, but if it is repeating, and the degree of that repeatability is small (great precision), it IS accurate. Just not to your desires. But with repeatability and precision, we can GET ANY desired accuracy, to the degree that we have repeatability and precision. As long as our resolution is up to it...

Precision would also dictate the degree to which our resolution is attainable. Repeatability means the same thing, and gives us the same results.

What I really want to know is how 1000 people would answer these questions:

If something is designed to be exactly one inch long, and every part made is exactly 1-1/4 inch long; are the parts precise?

Are they an example of precision work?

Is Accuracy derivative of repeatability?

Is Accuracy derivative of precison?

Can precision exist without accuracy?

In all of this I can easily accept that repeatability and precison are the same. But I still find it very hard to call something precise which is not accurate...

Ballendo

P.S. Maybe my electronic background is "leaning" me like Phil says it is leaning him... I do know that in that field we are cautioned to carefully consider the QUALITY of each digit, when determining its significance. Especially since digital came along, and we now have the ability to post very "precise", but totally wrong--or at least meaningless-- digits

In the PS above, I would prefer to write --seemingly-- in front of the word precise...

pminmo
02-21-2004, 11:19 PM
A reccuring definition in the dictionaries is exact, no more no less.

FRAMEDNLV
02-26-2004, 12:32 AM
Can i have a try at this?
Precison would be setting the units in cad up to 8 decimal places. Accuracy would be using object snaps in autocad. So if you have precision it doesn't mean anything when the darn drafter have that close enough attitude. In the end it looks right when it is plotted.

If I recall a couple of years back we all had a common problem with Precison and accuracy. "Y2k bug" the two digit date code was accurate. The precison was not.


Just my thoughts,
Chris

High Seas
02-27-2004, 01:08 PM
Missing POST?
Just wondering if anyone saw my last POST. Its the one that followed pminmo's last one on the 22nd/23rd -- and started with a smat alec remark about KISS - meaning Keep it Simple?
It was a short one - and I'd like to get a copy of it back for my files - I didn't save it and it seems to have slipped off this thread.
Any ideas - I did see it here a day or so after posting - or is this a case for Mulder & Scully?
:cheers: Jim

balsaman
02-27-2004, 07:19 PM
I don't see it and the moderators didn't delete it....not sure bud.

E

High Seas
02-27-2004, 09:43 PM
musta lost it in the insert process or something - thanks mate!

sbrpollock
02-27-2004, 11:26 PM
Costello: Whos on first?

Abbott: Precisely!

Costello: Precisely?

Abbott: Precisely!

Costello: So I throw the ball to Precisely.

Abbott: NO!! You throw the ball to Who!

Costello: Precisely?

Abbott: Precisely!


I'm sorry guys I couldn't resist :)

HomeCNC
05-13-2004, 12:13 PM
I just purchased a "Touch" screen monitor and a 10 key pad for my CNC router. I do not like to pull out my keyboard tray to get to the mouse while the router is going. The touch screen is cool. I can press all the buttons in Mach 2 and lower or increase the feed rate or move to different screen all by touching the glass on the monitor! By having the small 10 key pad I should not need the keyboard for input at all.

I will be doing a product review on the "Touch" monitor soon.

Cold Fusion
05-13-2004, 12:32 PM
Any update on that second video we were promised?

HomeCNC
05-13-2004, 01:28 PM
Boy! Some people never forget! :)

My cousen is very busy now so I decieded to purchase my own DV camcorder. I will try to film something myself soon.

Patrick2by4
06-02-2004, 02:10 AM
" www.plitron.com

They have many to choose from. Just remember that you get two transformers in one toroid. So if you want 36VDC @20 amps purchase the 25VAC output at 10 amps. If you want 30 amps output get the 25VAC 15 amp toroid."
Hey Jeff, where can I read up on toroid transformers? I don't understand what you mean by this statement. by the way, your videos are awesome. I showed it to some of my friends and they were very impressed by your machine. (I'm in the process of getting parts right now, boy is this a expensive hobby!)

Pat

Photon
06-03-2004, 06:17 AM
Patrick, your avatar looks like it really needs to go to the bathroom. :D

(Sorry for the off topic, but couldn't help it)

Patrick2by4
06-05-2004, 02:03 AM
LOL :D

HomeCNC
06-08-2004, 12:24 PM
Hey Jeff, where can I read up on toroid transformers? I don't understand what you mean by this statement.

Well I'm not experienced in electronics as well. I don't know if it is standard that ALL Toroid transformers are setup with two single transformers inside of them or not. I only found this out on the first one I ever used.

When you have two transformers you have many options of how to connect them up. Let's say you purchase the 2 X (25 VAC output @ 10 amps). The connection can be:

1) keep both transformers separate. You will have two 110 VAC inputs that give you two 25 VAC outputs @ 10 amps each.

2) Connect the two inputs so you have ONE 110 input. Connect the output so you double the voltage and have one output of 50VAC @ 10 amps.

3) connect the two inputs so you have ONE 110 input. Connect the outputs so you double the amps and have one output of 25VAC @ 20 amps.

4) connect the two inputs so you have ONE 220 input. I have not done this so I don't know what the outputs would be.

The two connection methods are called "Parallel and Series" but I don't know which is which on the above examples.

HomeCNC
08-17-2004, 01:11 AM
I now have an updated (NEW) video of my CNC router at my website. It is showing me carving 1/2 of a model boat hull. When both halves were done, they fit together so perfectly. The link is http://www.homecnc.info/router-movie.htm

Im now working on my 4th axis. This has been put on hold but I'm trying to find the time to get it going again.

More later.

High Seas
08-17-2004, 07:19 AM
VERY NICE - thats a project on my adgenda too - and has been from the start! Just got get it up in priority I guess. Will ther be a deck too?
Cheers - Jim

fyffe555
08-17-2004, 10:23 AM
I now have an updated (NEW) video of my CNC router at my website. It is showing me carve 1/2 of a model boat hull. When both halves were do they fit together so perfectly.

Very Nice.... What software/process are you using to produce the toolpath?

HomeCNC
08-17-2004, 10:49 AM
What software/process are you using to produce the toolpath

Well, I started with drawings of the ship hull. They were drawings with full size dimensions of a three masted schooner. The drawings had all the rib profiles and the distances of each rib. Also they showed some profile lines in the horizontal direction as well. With this info I built all the wire frame data using Cadkey 19. Once I had the 3D wire frame done I moved the file to MasterCam. I like the way it creates surfaces. I skined the wire frame model. So now I had a nice looking outside shape of the boat hull. (full size). I scaled the full size hull down to something that my brother-in-law wanted and then I offset the outside surface wall to make the inside wall, (about 1/4").

I used MasterCam to generate the Gcode. I used Mach 2 controller to control my router. I did everything with a 1/4" ball cutter.

HomeCNC
08-17-2004, 11:15 AM
I figured out how to wrap a relief around a pillar using ArtCam. This is what I want to do with my 4th axis. When I start to build my house next year, I want to have some pillars with carvings on them as well as other carvings through out the house. :D

OH! I can't figure out how to upload my picture with this new forum!!! I clicked on "Insert Image" but it wants some kind of http code. How do I upload a picture like I have done before???

OK I just found it!!! :)

jacdav82
08-25-2004, 11:37 PM
I've only read the first 17 pages, the machine looks great! What is the toruqe-load of the the drive-ballscrew.

I designed a Sheet metel router 10 gauge MAX (limited to the motor 3hp 1700~RPM single phase. no gear box.

Your design looks good spreading the z-axis over a greater area.

I would like to be able to cut .25 easy .50 with a slow cutting speed. (Alum)

Any ideas?

HomeCNC
08-26-2004, 12:39 PM
I would like to be able to cut .25 easy .50 with a slow cutting speed. (Alum)

IN ONE PASS??? You will need a VERY ridgid machine. Our professional CNC mills don't do .50" in one pass. (Well, we don't do that, it might). :D

My advice is to keep the gantry as low as possible and keep the Z axis movement low as well. My router has an 8" pass-through. But I'm only cutting wood and I'm going to add a 4th axis in the horizontal plane.

HomeCNC
09-21-2004, 01:45 PM
Any 4th axis users out there?

I have the main base of my 4th axis done. It will not be long before I will be ready to add it to my router. I'm not sure how to set it up in my controller software. I'm using Mach 2. When I setup my linear axis (X,Y,Z) one of the questions was "how many steps for 1 inch of movement?". Is this the same question I will need for my rotary axis? Or will it ask me how many steps will it take to turn 360 deg?

Another thing I've been thinking about is... Where is the start position on a rotary axis? Will I need a home switch or do I just zero the axis where ever it happens to be?

turmite
09-21-2004, 05:41 PM
The units for a rotarty axis is in steps per degree. You can kinda get close with knowing your gear ratio, but in the end my system needed a lot of testing in motor tuning. I will be glad to email you my xml file if that will help.

Mike

HomeCNC
09-21-2004, 09:07 PM
OK. I will have it on a 4:1 ratio to the servo motor. The motor has 1000 steps per revolution. So in 4:1 that would mean I would need 4000 steps to turn axis spindle 360 degrees. So the step per degree would be 11.11111 steps per degree, I guess????

The control software can take a decimal number?

InventIt
09-21-2004, 09:56 PM
You could also set it up like a flat plane. Say your work piece is 10" in dia x 15" long you have 3.14x10= 31.4" "long" axis x 15" high. When you do your layout in cad your working in a flat plane 31.4" x 15" Substitute your X (or Y) axis for your rotary axis. This method is probably only good for certain types of work. Maybe carvings that wrap around a post or lettering that spirals up a cylinder.

Pix Please...When do we get to see it???????

turmite
09-22-2004, 01:39 AM
Jeff you have the general jist of it. I have a 16:1 ration on my drive system, (need more or a much bigger stepper) and at the moment I can't remember my steps per unit, but it does use the decimal point with three places to get the accuracy I wanted. I have rotated my axis 20 times one direction, reversed it, did 20 the other way and the axis returns to 0.0. I bet you are using servos aren't you? They will probably have better holding power than my 300 oz stepper. If you need more specific info let me know.

Mike

daytrader
09-22-2004, 08:04 AM
How do you handle mechanical backlash on the rotary axis? Are you using some sort of brake? Is your reduction via belt or gear train?

It seems with linear motion you can use ballscrews or always conventional mill instead of climb mill to always be against the thread in the screw. But with a rotary axis, I would think the cuts will usually be from the top of the part, and the cutting force could force the part to rotate in BOTH directions, unlike x y z milling where the force is generally in one direction.

Nick

HomeCNC
09-22-2004, 12:02 PM
In my case... The backlash will be almost nill. I am not using a standard rotary table that has gearing in it. I have built this from scratch. It is a spindle that will hold my lathe chucks and I will have a timming belt running at 4:1 ratio to my servo motor.

HomeCNC
09-22-2004, 12:49 PM
Inventit:

Are you saying that I don't need to go to the trouble of building a 3D model of my carving wrapping around the pillar! I can somehow use a planer 3D model relief and tell mach 2 to map the G-code from the X or Y to my 'A' axis?

I will have some pictures on the way soon.

HomeCNC
09-23-2004, 08:06 PM
This is what I have now. Still building the frame that will hold the spindle.

Below show's the spindle shaft being cut and threaded with a M39-4 to match the 9x20 chucks I have.

Graham S
09-23-2004, 09:15 PM
The problem with using a 2D model is that you still need to make sure that it matches at the edges when it is wrapped up by the machining process. It rather depends on what you are trying to do.

I did some text engraving by drawing text in 2D, I then just set the rotary axis up like it was a linear so it would do one full revolution when the g-code was telling it to move the length of the box in which I drew my text. Nice thing about it is that you can run the same g-code on cylinders of different sizes, you just need to change the scaling of the x axis so the aspect ratio of the text is maintained.

Nice machining!

Graham

Bloy2004
09-23-2004, 10:07 PM
Hi Jeff,
I'm watching you ...again... and learning!

InventIt
09-24-2004, 08:48 AM
Graham s,
Good point. It would/may be difficult to get a match at the edges. I guess I was thinking more along the lines of a grape vine spiraling around the post for instance. It would not meet at the edges. Or like you said, text wraped around a post. The other problem would be a post that tapers. A 2D layout would not compensate for the decreasing dia. Am I correct?

HomeCNC
09-24-2004, 06:05 PM
The problem with using a 2D model is that you still need to make sure that it matches at the edges when it is wrapped up by the machining process

This is still the problem I had when I used ArtCam and made my 3D tube with the grapes on it (post 183). I had the problem of lining up the relief when it goes off the edge.



The other problem would be a post that tapers. A 2D layout would not compensate for the decreasing dia. Am I correct?

This is why I used ArtCam at first. You may not be able to tell this from the picture I posted in post 183 but that pillar with the grapes is really shaped like a football. It is very slight though.

I was just trying to think of an easyer way than what I did. It may be that using ArtCam will be the best solution after all.

When I get done building this 4th axis I will try both ways.... If I can get it to work at all :D

turmite
09-25-2004, 10:23 AM
Hey Jeff you might try this link. Rab used one of my gunstock designs, (crude design) to make a 4 axis tutorial using his Toolkit software which is a macro for Gmax. Both Gmax and toolkit are free so you might want to at least give it a try. I need to print of the txt of the tuts and then I will give it a try.

http://www.rainnea.com/cnc_t_4axis.htm

Mike

HomeCNC
09-25-2004, 12:50 PM
Yes, I do know about Rainnea. I have installed the Gmax software onece before, and looked at the toolkit. Having a tutorial will help greatly! I was having some trouble figuring it out.

HomeCNC
11-11-2004, 01:36 PM
Last night I did my first REAL 4th axis project. When I say real, I mean that I did not connect the 4th axis to the Y axis driver. My post was using the 'A' axis. This first attempt was not without problems. When I test ran the code within Mach 2 4.0 release. The rotary axis jumped a bit on the first cut. There was nothing in the code to cause this. So I decided to look for a newer version of Mach 2. I found Art had a version 6.11C, so I downloaded it. It must be a beta version because there are problems with it. The rotary jump was not there so I used this version.

I had set the same motor tuning from version 4.0 into 6.11, but it did not like the same settings for some reason. I had to play with tuning when I first went to 4.0 as well. I don't know why Art makes changes in the way a motor runs between versions. I still did not have the tuning correct, when I did the pillar below so I just kept the feed rate down.

Another odd thing, or maybe it is normal. The 4th axis moves very slow compared to the other axis. What I mean is.... The jog works fine with the 4th axis, it moves fast. When I set a feed rate in the program to 60 IPM. The X and Z axis would move at that feed rate. When a "A" axis move was issued the feed rate would drop to around 1 IPM then go back to 60 when it was done moving. There was nothing in the code to tell the feed to drop. I'm going to ask Art about this. Maybe he does this on purpose.

Anyway you can see my pillar carving below. The first two pics are when it was roughing. The last pic is after I finished the 1/4" ball mill cut. Notice that the grape vine is not on a straight pillar. I made the pillar a slight football shape.

kong
11-11-2004, 01:45 PM
Truly amazing! i like the "simplicity" of your 4th axis setup too. So was the program a "true" 4 axis movement, or was it only utilizing 3 of the axes? I am interested as it may be a nice winter project, but I can't afford your software.

HomeCNC
11-11-2004, 01:48 PM
Hi Kong,

It was a true 4th axis movement. The post from ArtCam translated the Y axis to Degrees of movement. I really do love ArtCam, It may be expensive but it does everything I want.

Oh I just re-read your question. The tool must stay on center of the axis. This is why there are no Y axis movements. The Y axis was translated to angular movements of the 4th axis.

kong
11-11-2004, 01:57 PM
Sorry for keeping on Jeff, what I meant was does the y-axis actually move during the cut, or does it stay centered on the workpiece? i know there has been a lot of talk of "unwrapping" a 3d drawing to convert to the a-axis system, so I guess this is what I will have to do without the proper software :(

HomeCNC
11-11-2004, 02:08 PM
The cutter must stay perpendicular to the surface. If my 4th axis was the router, Which would mean I would need to build a pivot on the router mounting. Then the Y axis could move over to the side of the pillar, the Z axis would move down and the router would pivot to keep the tool perpendicular to the surface. In order for the tool to stay perpendicular with my setup, the Y axis must stay on center.

InventIt
11-11-2004, 08:04 PM
Very Nice! How long did that cut take? I like the design of your 4th axis. Simple yet effective. What size chuck is that? 3" or 4"?

Nice job.

HomeCNC
11-11-2004, 09:20 PM
Thanks InventIT,

The total time is something I don't know. The roughing took about 1 hour. I started the finish cut and went to bed. When I got up it was done!

The spindle that I made for my 4th axis is the same as the 9 x 20 lathe. I was using the 3" chuck this time but I can also fit my 6" bison on it, the 4 jaw or the face plate that I have for my 9 x 20.

ger21
11-11-2004, 09:41 PM
I had set the same motor tuning from version 4.0 into 6.11, but it did not like the same settings for some reason. I had to play with tuning when I first went to 4.0 as well. I don't know why Art makes changes in the way a motor runs between versions. I still did not have the tuning correct, when I did the pillar below so I just kept the feed rate down.

Art made a lot of changes in version 6 which supposedly make the pulse train much smoother, perhaps this has to do with your problems. I read the Mach2 group daily, and 6.11c is supposedly very stable. Be sure to let Art know of any problems, he'll probably have them fixed in a day or so.

Chagrin
11-11-2004, 11:41 PM
If you're still thinking about chucks you might consider one of these from Grizzly. They run under $40 and you can fairly easily build some large flat-faced jaws for a better grip on the wood.

http://images.grizzly.com/grizzlycom/pics/G/G8786.jpg

HomeCNC
11-12-2004, 03:58 PM
Well, I got an answer from Art about the slow moving 4th axis. Somewhere on the setup screen there is a place to tell mach 2 the diameter of stock you are working with. I will check this when I get home tonight.

walter
05-15-2005, 01:06 AM
This is still the problem I had when I used ArtCam and made my 3D tube with the grapes on it (post 183). I had the problem of lining up the relief when it goes off the edge.

Jeff, Is the seam on the back of the 3d tube visible after machining? And how did you solve the problem with lining up the relief on the edges?

thanks

HomeCNC
05-19-2005, 01:18 PM
No edge is visable on the finished carving IF you spend the time to get the graphic lined up. I placed a grid pattern over the graphics to help me get close. I then did some trial and error work to get the relief as close as I could. It worked!

coych
05-19-2005, 02:46 PM
I am wanting a home machine. Ive searched and I am not ready to remorgage the place. I am looking for at least a 48x48 . I am not looking for mass production. I have access to mastercam. Any suggetions or references to other companies besides shopbot. Cant afford $7,000 plus.

JavaDog
05-19-2005, 03:23 PM
I am wanting a home machine. Ive searched and I am not ready to remorgage the place. I am looking for at least a 48x48 . I am not looking for mass production. I have access to mastercam. Any suggetions or references to other companies besides shopbot. Cant afford $7,000 plus.

You might want to start a whole new thread, that way it would get some attention and we could go over your needs, etc etc. ;)

walter
05-26-2005, 10:11 PM
No edge is visable on the finished carving IF you spend the time to get the graphic lined up. I placed a grid pattern over the graphics to help me get close. I then did some trial and error work to get the relief as close as I could. It worked!


Thanks for the reply. I started worrying when I lerned about ArtCam Pro "semi 4 axis" capability. It`a a lot of money and you want good result when working on these fancy turnings. :p

wisp
05-27-2005, 10:47 AM
Another odd thing, or maybe it is normal. The 4th axis moves very slow compared to the other axis. What I mean is.... The jog works fine with the 4th axis, it moves fast. When I set a feed rate in the program to 60 IPM. The X and Z axis would move at that feed rate. When a "A" axis move was issued the feed rate would drop to around 1 IPM then go back to 60 when it was done moving.

Jeff, the reason for the feed change is that 4th axis angular moves are in degrees per minute. So a feedrate of 360 would be one RPM on the 4th axis. That is how Fanuc controls feedrates when using a 4th or 5th axis.

Here is the formula to convert inches per minute to Degrees per minute,

DPM = 360 x IPM / (Diameter x Pi)

cheers.

HomeCNC
05-28-2005, 01:09 AM
Thanks for the information. I have been away from using my 4th axis for sometime now, but when I get back into it I will look at your formula and try some tests.

jkhlaw
06-02-2006, 03:27 PM
Dear all,
I am think of making an automated cnc saw using spiral saw (rotozip) with 3 -axis machine to saw multiple piece of smaller rectangle wood from a large wood (6'X8') at one go without human intervention.

I am sure can be done in the cutting part but what about the clamping part.

Could anyone share some light with me pertaining automated clamping on automated cnc saw.

Thank in advance.

Jimmy

joecnc2006
06-02-2006, 03:57 PM
Dear all,
I am think of making an automated cnc saw using spiral saw (rotozip) with 3 -axis machine to saw multiple piece of smaller rectangle wood from a large wood (6'X8') at one go without human intervention.

I am sure can be done in the cutting part but what about the clamping part.

Could anyone share some light with me pertaining automated clamping on automated cnc saw.

Thank in advance.

Jimmy

Isn't that called a cnc mill? I would not do a vertical if that is what you are thinking, because the pieces will just fall down, then you would need a vac table system to hold the all the parts inplace.

James Marshall
11-23-2006, 07:35 AM
Hello. Have you ever decided to make the drawings for your tool holder available ? I would be interested if so. Hows the house coming along? Thank you.

William A. Lowe
11-26-2006, 08:33 PM
You didn't say how large a motor you are using to turin the spindle. Wood shapers would usually use a 2 or 3 HP, 3750 RPM motor at apx. 7000 HP. The slowest router I have seen is 16000 RPM x 2 flutes = 32000 cuts per min.

At 20000 cuts per min. you would have to move very slowly to cut wood, but I don't think you would clear the shavings ( sawdust ) from the cut and the machine would "bog down." Without clearing the shvings you will aneal the cutter and it will become dull very quickly.

HomeCNC
11-26-2006, 10:52 PM
Hi James,

I have been away from the zone for a long time now. I have completed building my shop first and I started on the house this summer. I got the shell completely up in three months by taking two weeks of vacation from work to frame the lower floor and then did the rest by taking every Friday off. With the help of some family & friends on weekends, this is where I was at the end of October 2006 see picture. You can see the edge of my shop to the far right of the picture.

As for the Porter Cable fixed collets that I designed. I did post the drawings here in another thread. I have searched for it but it seems that It no longer exists on this server anymore. I have attached them to this post as well.

Jeff

ViperTX
11-26-2006, 11:18 PM
Jeff....beware of weathered wood....

James Marshall
11-27-2006, 09:57 AM
Looks good!!! Should be a nice house when finished. Thank you for the drawings!!!!! Hopefully I will be able to put these to good use, I like to hide in the garage durring these cold Alaska winter days. The shop looks pretty big, got to love that!

qtronpowerson
12-05-2006, 11:33 AM
I managed to finish my Servo controller box this weekend. It worked great! I used a torid for the transformer this time. Wow do I like them.
What made U choose servo's...arent they much more expensive than steppers? $??
Costs aside, What is the main determinant in choosing?
How did U determine the appropriate servo motor horsepower/wattage ouput?
Thanks, Qtron...

qtronpowerson
12-05-2006, 11:34 AM
What made U choose servo's...arent they much more expensive than steppers? $??
Costs aside, What is the main determinant in choosing?
How did U determine the appropriate servo motor horsepower/wattage ouput?
Thanks, Qtron...
meant to say Toroids can be torid with fuses!!

Khalid
09-06-2008, 09:46 AM
Any Updates Jeff?:)

HomeCNC
09-06-2008, 10:52 PM
No updates with my CNC router, but I have a picture of my house and shop I'm still building.

Khalid
09-07-2008, 12:46 AM
Jeff..Please keep up posting of ur great work especially u r doing on 4th axis... I saw ur work of column u did in Artcam, what version of Artcam u are using???Are u using ArtCam pro 2008 SP5 ? I am facing repeatable crashes with this latest version while unwrapping 3D model...Any tips u can give me to avoid this???

Khalid
09-08-2008, 05:53 AM
Wow what a beautiful place u are living at:)

IntarisiaQ4
10-18-2009, 07:49 AM
HI THERE!!!
This is the information I have been looking for, could you please send me information about this matter. I have a 5-axis machine and I want to take advantage of the A-axis for turning round extrusions. I have the post processor needed for my machine which runs with Mach 2 software.
I really appreciate any help you can give me to turn round a relief.

Thank You very much
Eduardo.

CarveOne
10-18-2009, 07:56 AM
Hi Eduardo,

His website (http://www.homecnc.info) has a contact link if he doesn't respond here soon.

CarveOne