Ok, I am about to embark on a Enco style round column mill-drill conversion.

This one specifically:

http://www.kingcanada.com/Products.htm?CD=36&ID=121

I just ordered:

3 Gecko 320 drives
3 USDigital 250 CPR encoders
3 Amtek surplus DC motors, 50 volts, 2100 RPM

So, a couple questions:

I have read all the horror stories about the round column mills and the PITA when you need to reposition the head on the column. My question is, if I can live with the 5" quill travel, does this mill do a good job machining with the quill extended?

What are the odds that I can build some sort of external keying (using THK rail and bearings) into the round column and move the whole head up and down on the column as a z axis? If not that, perhaps I can still use the quill for z but use the keying to keep the head in position on the column when manually moving the head?

What do you think of using the stock lead screws? I am considering the Mcmastercarr 5/8" rolled ballscrews but are they any better than the stock lead screws as far as acuracy is concerned? I know they would be more efficient. Also If I used two ball nuts for preloading will they bind because of the fact that the screw is rolled and thus not that acurate?

Anyone with experience out there I would apreciate your feedback!

Eric

What did the mill cost you?

It's used. $800 CAD. They cost $1500.00 here new at www.busybeetools.ca

Here is the link: http://busybeetools.ca/cgi-bin/picture?&NETID=2225501129040650060&NTITEM=B1977

Eric

balsaman,
Looking at the add in your post makes me think the mill I have and yours are almost twins. Only the paint job looks different! As I have/am doing a conversion of a round column mill, I think I can speak from some limited experience.
1. Existing lead screws> for get IT (Don't ask:}) I used Roton rolled ball screws and am perfectly happy. With the original screws due to some problems, I was getting up to .250 backlash (and the mill hasn't seen THAT much use). I made my own pre-loaded ball nuts and the other day, I was doing some engraving and it would have shown up big time if I had any real backlash. Looked good to me. I wasted several months using the existing lead screws.
2. Can you live with the limited quill travel. Well, so far, I have; but it takes a creative setup. For "table" mounting, I made a raised table with a piece of 4x4 tube so I had room at the end to do the necessary tool changes. The vice makes the part raise up sufficiently to handle that part all by it self.
3. Finish, is satisfactory for the stuff that I do. Again, YMMV depending on how accuracte and how heavy a cut you take. I find for my purposes that a 3/8 mill is about as big as I want to go and not have problems with rigidity of the machine.
4. Unless you are a genius (and you may well be), the idea of moving the whole head is a tough nut to crack on a round column. Keeping it in line will be very difficult. If you figure this one out, there are a LOT of us out here that would like to know how you do it. (Keep it in line and do it "cheaply")

If I can give you any assistance, PM me.

Bubba

I was just contemplating the hf 3 in 1 or possibly their version of the same mill you are converting, at 1000 bucks usd, i'd have to drive to buffalo to get it.
Balsaman are you in the GTA? (you dont have to answer), busybee on dixie rd mississauga is around the corner from my work, and if they got more at that price.....
this is what i was contemplating...
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=33686

Well Balsaman, Welcome to the club :)

Balsaman,

I have used my cnc drill/mill for a long time. I have never had to reposition the head once my job has started. I think the trick is to get screw machine length drills. Check out my website on how I keep my tool lengths very close to the same length.

truble,

That's the one. The used one I am buying is a private deal, not buying it from busybee but from an individual who bought it there originally. I am not from GTA, but in Woodstock. An hours drive.

Bubba,

Ok, I will go with the ball screws and two ball nuts per axis. I need to pick up the mill this week and have a better look at it before I know what to buy. Did you use 5/8" ball screws? The ones I am considering are the 5/8" x 13/64" at $1.09 per inch plus $21.04 per square nut.

I will be posting regularly on the progress with lots of pictures so everyone will have lots of time to tell me how to do it.

Eric

HomeCNC,

I have seen your website. I was glad when this mill turned out to be the same one you did. At least I know it can be done!

Eric

balsaman,
I used 5/8 screws .2 pitch and got them from Roton.com. I got a 5' length for $43.25 USD and the ball nuts cost $19.40 each. Their wipers are 9.65 ea. Also be aware that they have a $40.00 minimum. I ordered 2 sets of wipers expectimg to get 4 but only got 2. So I used an idea that I got from another group and made my own. Not real pretty, but they work. As for turning the ends of the screw, my atlas is not rigid enough to cut through the hard stuff so I rigged up a tool post grinder out of my die grinder and simply ground the diameter down. Once under the hard stuff, it was easy to thread the ends as necessary.
There are a few pictures on my web site:
http://bellsouthpwp.net/A/r/Arts_home_page/cnc/

Bubba

Great, thanks. I will order from Roton.

Eric

Hey, Eric... Check out the cost of getting the nuts preloaded. It may be cheaper than buying two nuts.

I happend to have a Jet JMD18 (which is really a Rong Fu 30) with round column that I'm planning to CNC. It is the round column and in 10 years of manual machining I've learned to plan my machining and I adjust the column prior to starting a project. http://www.tomsinstitute.com he did a Grizzly 1005 CNC conversion and has an interesting way of creating ballnuts with minimal backlash using 2 ballnuts, a spring and holder. Do you have a website?
I've got the Ametek motors and bought some 500 CPR encoders, haven't bought the Geckos they are on sale at geckodrive.com , I just bought all the parts for the 40 VDC supply, which I'll build this weekend.

Hey, Eric... Check out the cost of getting the nuts preloaded. It may be cheaper than buying two nuts.

I will. Didn't know they came that way. Thanks.

Eric

Just posting to keep an eye on this thread. I have that exact mill and have been dying too convert it for the past couple of years. I've been lurking here for quite some time, hopefully following your build will drive me to start. :)

I made my own pre-loaded ball nuts and my inspiration was Toms Insititue, however I used a little different approach. I made a "socket" that fits over the back end of the front nut and then a knurled nut which is pinned to the "socket" by one or two 6-32 screws. I used "wave washers" from McMaster to pre-load the nuts. Works great for me.
You can see some pictures of how I did that and made my own wipers also at:

http://bellsouthpwp.net/A/r/Arts_home_page/cnc/

Yeh, I know, a repeat and should have thougt of explaining that the first time:{(

Bubba

I am waiting for some parts to arrive and I need to pick up the mill. I promise you I will update once I have some more to post.

Eric

Hmm, motors arrived this morning but I was not home. Gecko's are here. Still waiting on the encoders.

Love those wee little gecko's. Hard to believe they are good for 20 amps.

Eric

I used hot glue to make my ball screw wipers. All you do is oil up the ball screw with some thin oil. make sure you don't get the oil on the ball nut housing. I held the ball nut in my vise with the screw vertical. Heat the ball screw just a little with a torch. Now fill the area where the ball screw enters the nut with hot glue. The glue will conform to the thread of the ball screw and make sure you get glue all over the end of the nut housing. You want the glue to stick to the nut. When the hot glue hardens you give the screw a turn to break it free.

Do the same procedure on the other end of the ball nut.

I used hot glue to make my ball screw wipers. All you do is oil up the ball screw with some thin oil. make sure you don't get the oil on the ball nut housing. I held the ball nut in my vise with the screw vertical. Heat the ball screw just a little with a torch. Now fill the area where the ball screw enters the nut with hot glue. The glue will conform to the thread of the ball screw and make sure you get glue all over the end of the nut housing. You want the glue to stick to the nut. When the hot glue hardens you give the screw a turn to break it free.

Do the same procedure on the other end of the ball nut.

That is a great tip, I think I'm going to try that.

Well, my 3 motors arrived from www.surpluscenter.com. They are 50 volt DC brushed motors. Unfortunately one was damaged before it got here (before it was even packed it seems, since the box was in great condition). An email to the surplus center and they are sending another at no cost to me.

I disassembled a motor to have a look inside. They look very lightly used. Perhaps just test run. Commutator is nice and the brushes long.

I figured I would start getting the motors ready for the encoders. The encoders I ordered go on a 3/16" shaft, so I need to add the shaft to the back of the motors. I chucked up the motor armature in my lathe and checked for runout at the commutator end. Just a half thou so I went ahead and centerdrilled it. I think I will just drill and ream to 3/16" and then use locktight to hold the little shaft in. Not like it's gonna be hard to spin that little wheel inside the encoder.

By the way the motors are these: http://www.surpluscenter.com/item.asp?UID=2004120920573212&item=10-1552&catname=

I sent away to Ametec to get some more specs on them, since all I know is 50 volts, 2100 RPM. I will probably go 2:1 or 1.5:1 ratio to 5 TPI screws, depending on what the motors are rated at current wise.

Eric

Ok got all three armatures drilled and reamed to 3/16. Used blue locktight to hold in the shaft. Here is an example ready for encoder. I ran the motors on 12 volts. Turned slowly but LOTS of torque.

By the way for anyone who has done this conversion, how much 5/8" ball screw did you use? Did you order one lenght and cut it or 3 lenghts precut?

Eric

Nice price on those motors, how many amps do you give them and what motors did you get? theres about 4 models of similar motors.

Jon

This one: http://www.surpluscenter.com/item.asp?UID=2004120920573212&item=10-1552&catname=

50 volts, not sure about amps yet. Waiting for specs from AMETEK. They will have lots of power.

Eric

I bought a 6 ft. length of 5/8" ball screw from Ried Tool which left about 16 inches for some practice turning. That alloy steel is tough to cut on a 1947 South Bend benchtop lathe!
BTW, kudos to Servo King for the nice set of plans and motors (no financial interest). I'm hoping to have the conversion completed by feb.

-Steve

Balsaman,
YOU have sufficient information to figure the paramaters for your motors!
Below, is the "how to" from our friend Mariss.

"1) Connect the field coil and the armature to a power supply you intend to use with this motor.
2) Use a tach to measure the motor no-load RPM.
3) Calculate the Kv by dividing the supply voltage by the measured RPM and multiply the answer by 1,000. That will be the motor's Kv (volts per 1000 RPM)
4) Multiply Kv by 1.351 to get the motor's Kt. Kt is in-oz per Amp.
5) Calculate the max continuous torque by dividing the motor's rated voltage by its armature resistance. Multiply this by 0.2 and multiply the result by Kt from (4). That will be the maximum continuous torque you can use.
hope that helps.
Mariss
This is very important with servo motors. Bad mechanicals will give crappy performance with step motors but it will not hurt them.
Bad mechanical design will also give crappy performance with servos with the added feature of burning the motors (and drive) out as well. REALLY IMPORTANT;
you have to be much more careful with servos for that reason.
If you already have a motor adequate to the task:
1) Start by finding out what your motor's no-load speed is at its rated voltage. Use a strobe tach if you don't have the data.
2) Design for a speed equal to 80% of your motor's no-load RPM when your mechanism is moving at its maximum speed.
3) Calculate the RPM of the driven element (leadscrew, etc, etc) when the mechanism is moving at its max speed.
4) Divide that RPM into 80% motor no-load speed. That will be the optimal reduction ratio from motor to load. Use a toothed-belt for anti-backlash reduction.
5) Determine what is your software's maximum step pulse rate. It'll be published somewhere. Convert your motor no-load RPM into revs per second (divide RPM by 60)
and divide that by 4. Divide that into your software's max step frequency. The result will be the maximum encoder line count.
Pick the next lowest standard mfg encoder line count. In other words, if your result is 566.66 lines, pick a 500-line encoder."

You can jump the the first step three as you already have the Volts and Rpm. I have similar motors (48V 1000 RPM) and for math purposes simply used a VOM to find the armature resistance. Not perfect, but close enough for my intent. Also, I included a followup post from him concerning maximum parameters to use in the design of the reduction and encoder count.
I set all this information up in a spread sheet to be able to play with the variables and must have done something right as the setup works quite well.

Hope it helps you in your setup. :cheers:

Bubba

Ok, in that case my motors have a Kv of 23.8.
This computes to 32.17 oz-in/Amp
Since the winding resistance is 2.2 Ohms, I get 108.18 oz-in max continuous torque.
This should also mean that the motors are rated 3.3 amps continuous current (108.18 divided by 32.17)

I would be nice to get 150"/min.
This means the .2 lead screw needs to spin 750 rpm.
80% of 2100 rpm is 1680 rpm
@2:1 ratio I get 840 rpm at the screw. Close enough.

Anyone have the calculation for peak torque?

How about how to calculate force at the tool?

Thanks for the help. I was going to use the THAR method, which has served me well in the past, and it looks like I was in the ballpark. Good to see the numbers though.

Eric

Oh and at that rpm and 250 CPR encoders I need 28 Khz from the software. I don't think that is an issue with Turbocnc or Mach 2.

Eric

Maybe this link may help a little with some information:)

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=26261&item=3859168279&rd=1

I have seen those. Slightly different than the ones I have. Those are 40 volt 1000 rpm.

Eric

Balsaman:
I'm thinking of purchasing the same drill/mill with the intention of useing it manually at first then later converting it to cnc. I want it to cut keyways in shafting for various projects and I don't have the budget for a knee mill (yet!!). I was thinking this would be a cheap start up machine. What are it's limitations and such in your opinion?

Balsaman:
I'm thinking of purchasing the same drill/mill with the intention of useing it manually at first then later converting it to cnc. I want it to cut keyways in shafting for various projects and I don't have the budget for a knee mill (yet!!). I was thinking this would be a cheap start up machine. What are it's limitations and such in your opinion?
If I were purchasing today, I'd get one of the non-round column mills..like the Sieg X3 for light duty machining. I believe that Grizzly has a square column mill for around $1800 which appears to be heavier duty then the X3.

You might want to check out the mill at lathemaster.com Its similar to the grizzly for cheaper, Industrial hobbies has one like it too with a bigger table.

Jon

How are you going to handle your Z axis?

On the round columns you just adjust the spindle over it's 6 inch travel. The column is manually set.

Not sure yet....I am picking up the mill tonight. Then I will have a better look at it. I know you used smaller servos so it fit inside the head. I won't have that option with these servos. Once I work it out, I will let you guys rip the design to threads and then I will go ahead and do it anyways. :)

Eric

similar in concept maybe? http://www.cnczone.com/gallery/showphoto.php/photo/78/sort/1/cat/505/page/2
that is for the Z axis handle thing, could put it somewhere in there.

Jon

Maybe with the y motor flipped around and a shorter belt with a guard. Don't see the z axis....

I got it home and yeah, the z axis is an issue. I may have to go with the Jeff Davis thing with a smaller z-axis motor....The above link shows an other option. Not quite as clean as Jeff's tho.

BTW, that this was heavy!

Eric

You will like the weight when you start using it. A drill-mill is not a bad machine for the price!

Encoders came today. The E4 series from USDigital. 250 Cpr. Very tiny. here is a pic.

Eric

Hey Jeff, did you loose any of your x travel with your conversion? I might loose a couple inches.

Eric

Hey Jeff, did you loose any of your x travel with your conversion? I might loose a couple inches.

Eric

Yes I think it was only a few inchs as well. Why did you go with the E4 encoder? I use the E2.

It was 10 bucks less. I bought the 6' cables with it. It should be fine. Very small tho.

Eric

I've got the E2 encoder from US Digital for my servos....I'm suppose to build my supply this weekend (toroid based)....got all the parts except the chassis....

Here is the mill. Needs a good cleaning.

Eric

Balsaman,
NOW THE FUN BEGINS:})
Yours looks exactly like the one I did, even down to the puky green color!

I have PMd you regarding your request, but realize I also have additional information for all axes and our servo motors are pratically identical also! Don't worry about the loss of the X handwheel, as you won't need it except to make the parts for your new cnc.

I would also suggest putting some "weight" in the stand as I have read this helps with the vibration that occurs and makes it much more steady.

Good luck and keep similing as there are days that will seem like crap:{(

Bubba

Actually there was the power feed unit there. Anyone looking for a power feed for one of these?

I took the power feed off to take some measurements for where to bolt stuff for the x axis servo motor assy. The mill came with the hand wheel as well. Also a whole big toolbox full of tooling (maybe 50 endmills, clamping set, collets, drill chucks and a nice adjustable boring tool etc etc.)

Balsaman, Does this look familiar? (Ametek dc 50v servos) I bought these back in march from ebay, I think I may have proper info on them, I'll try and dig it out if you like?

tublshtr,

Mine are part number 116150-02. Similar but different I believe.

Thanks anyways

Eric

Balsaman,
you are right my part # is 116870-01, 50vdc @36/amps and 2000 uf needed/amp.

Re: power feed.
I'd be interested in the powerfeed. I'm planning to purchase a drill mill like that and would need a power feed for it but I'm unsure if the power feed will fit. I plan to buy the one you mentioned in an earlier thread from busybee.

I will PM you with details.

Eric

Balsaman,
you are right my part # is 116870-01, 50vdc @36/amps and 2000 uf needed/amp.
Are you sure they are 36 amp units?

Oops, sorry , you are right, I was looking at my Total needed amperage for driving 3 of these servos...... :rolleyes:

Well, today I made the bearing blocks for the x and y. made from 1" thick aluminium. Drilled on my mill, then the bearing hole bored to the right size on my lathe with a boring bar. There is a lip in the center on which the two timkin tapered roller bearings sit. This will allow me to adjust out all the backlash. The screw will be turned down and threaded to allow a nylock nut to tighten against the inner races of the bearings.

Eric

@Balsaman: If you have another motor, mount the encoder using this method:

Smear the end of the motor shaft with grease to avoid chips getting into the bearing. Then mount the motor in your lathe so the body is held steady and the shaft is allowed to spin. Power up the motor and drill the hole in the end of the shaft using a drill mounted in the tailstock. Then scrape off the grease making sure to remove any swarf with it.

The reason for doing it this way is that if you take the armature out of the motor without pushing a thick-walled tube in behind it, the magnets will demagnetize. Not totally, but enough to seriously weaken the motor. How I know? I learnt this after i did it like you, and now I have one motor with full power and one wimp. Then I went searching for why, and found the reason as mentioned above. So the second motor was done as I suggested, and works fine.

I might as well mention another way to demagnetize a servo motor: Just hook it up directly to a car battery. In other words: don't do that! The startup current may demagnetize it even if the motor is not connected to a load. The max current should not be exceeded even for a fraction of a second. Max current rating can be up to 4 times the max continous current rating.

This, and my previous post only applies to permanent magnet motors. And not to all of them. But usually you will only know if it applies to your motor after you tried.

Since one of my motors was damaged, I used that armature to insert into the motor while I drilled the other armatures. Good advice tho.

Eric

I'm not sure if that can be done without interrupting the magnetic flux though. A thick walled tube can be made so it pushes out the armature following it closely without interrupting the flux.

It will probably be powerful enough even if it lost some. That motor looks like the ones I have. It came from an old computer tape deck, and has a huge grunt. So even if some is lost, it will be able to shake your mill about I guess. ;)

@
The reason for doing it this way is that if you take the armature out of the motor without pushing a thick-walled tube in behind it, the magnets will demagnetize.

I think this may occur with older or motors constructed of some cheaper magnetic materials, but current motor manufacturers are always striving to produce better permanent magnets, from e.g. Samarium Cobalt and Neodymium Iron Boron, not only do these materials no longer need a magnetic keeper, they have very much increased magnetic strength and result in up to a 50% decrease in motor size for the same torque.
Alnico is one of the ones you need a keeper on.
I guess I have been lucky, as all of the servo motors I have dismantled for repair etc, I have never had one that had reduced performance after re-assembly. The Last one I had to do was a 2hp DC Gettys that had been dropped in shipping and the pole piece had come loose from the stator. It took a while to find the right adhesive.
Al

made some z axis parts today. tried some external and internal treading too. Worked out nice. This part is the pulley adaptor that will allow the ball nut to be spun. Shown with one of the bearings on there. It will all come together once I have the nut and pulley on there with the other bearing.

Eric

I had to take apart my mill so I could measure these parts, then put it back together to make them. I don't have the "unobtanium" 15/16" x 16 tap so these parts were clamped in my 4 jaw and bored and threaded on the lathe. They hold the x and y axis ball nuts.

Eric

Balsaman,
When I put my X nut on the table, I also "pinned" it after alignment to be sure that it would NOT move. I had a problem with the original nut sliding slightly under hard stop conditions.
You can see a picture of how I did this at:
http://bellsouthpwp.net/A/r/Arts_home_page/cnc/
I also had to make sure the return tubes for the ballnut were in the horizontal postion to clear the table.
In the picture, you can also see a portion of the "Z" grouve that has been cut into the way for distribution of oil from the "one-shot" oil system along with some of the fittings and tubing for the oiling.

Your system is looking good, and I am looking forward to the finished system pictures.

Bubba

Thanks for the tip. I will see how it goes, and pin the nut down if required. What size screws did you use?

Eric

I got all my pulleys and belts on Thursday. I bored the z axis pulley to 1" today so it would fit on the z axis spinning nut assy. Here it is. That's the bearing, pulley, shoulder (of the hollow nut adaptor), another bearing, then a coupler to the ball nut. I have tape on the ball nut so the little cardboard tube won't fall out. This whole assembly will spin on the fixed z axis screw. Jeff Davis did it this way. Thanks for the idea!

I am cutting the ends of my ball screw today. It's really hard. I could swear my little lathe is made of wood. I ended up anealing it with a propane torch and cutting it with carbide insert tooling. I still need to thread a section for a 1/2x16 nut. I hope my HHS threading tool can hack it.

Balsaman,
I used 5/8" screws for the X and Y axis

I really like your Z assembly and look forward to seeing it finished up. I did mine on the micro feed.
As for the threading, I found that HSS tooling did fine as I was under the hard stuff. Still found a couple of hard spots, but it cut through it ok. In other words, the nut would feed on. By the way, I used 7/16-20 as my thread to hold the assembly together.

Bubba

I cut the thread 1/2-20 (not 1/2-16) and it worked fine. I now have one axis (y) moving with its new screw. Moves much more easily than the stock screw, even with the gibs quite tight. Working on x now...

One of my goals is to still allow for manual machining. I am leaving enough material on the screws so I can put the handles back on.

E

Sounds good, whatever works is best:})
As for the handles, after reading several threads on the pros and cons, I lost mine and have never looked back! I have gotten to the point where "flying by wire" is just as quick and easy [and definately more accurate] than twisting handles. Actually, make that quicker especially when moving the table full length and I don't loose count.

Bubba

Well,

This isn't my first cnc machine. I have built 2 routers. They didn't have handwheels. The plan is to make the hand wheels either forward and engaged onto the coupling or slid back and free wheeling (like the big mills that have power feed). The z axis will need to be mechanically disconnected. The way I look at it is it's easier to lose them after if I find I don't need them then it is to add them back on later.

I know there are pros and cons. Just trying to keep as many options open that I can.

Eric

Sounds good, whatever works is best:})
As for the handles, after reading several threads on the pros and cons, I lost mine and have never looked back! I have gotten to the point where "flying by wire" is just as quick and easy [and definately more accurate] than twisting handles. Actually, make that quicker especially when moving the table full length and I don't loose count.

Bubba


Me too! I have never missed my handles on my mill :)

Here is the x axis screw with it's thrust bearing. I forgot to account for the 2.5" spacer between the bearing block and the table. The spacer was to give the motor assembly clearance to allow for more x axis travel (so the x axis motor doesn't hit the y axis ways). The screw is now 2.5" too short, which means no spacer or no hand wheel. No hand wheel it is for now. I could always make an extention for the screw if I need to.

Screw installed

X and Y running on the new screws. You can see the 2.5" spacer on the left.

Is that a laser level in the photo of post #76?? If so how accurate is it at reading level?

Hager


Here is the x axis screw with it's thrust bearing. I forgot to account for the 2.5" spacer between the bearing block and the table. The spacer was to give the motor assembly clearance to allow for more x axis travel (so the x axis motor doesn't hit the y axis ways). The screw is now 2.5" too short, which means no spacer or no hand wheel. No hand wheel it is for now. I could always make an extention for the screw if I need to.

Balsaman,

What size power supply (Vdc) did you design for powering the 3 servo motors?

Thanks,
Al

Is that a laser level in the photo of post #76?? If so how accurate is it at reading level?

Hager

It's the handle of my chest style freezer....:)

Eric

Balsaman,

What size power supply (Vdc) did you design for powering the 3 servo motors?

Thanks,
Al

The plan is around 50-60 volts, 20 amps. I have a 1000 va transformer with many taps for different voltages and a 22,000 uf, 75 volt capacitor so far.

Eric

It's the handle of my chest style freezer....:)

Eric

So how accurate is your freezer at reading level ?!
Sorry, couldn't resist, great job so far Eric, I will just add my 2 cents and agree that after a while, the handwheels will be easily forgotten. i have found that on the lathe now, particularly when using the DRO's in Mach2 with a set jog speed.

Duhhh.
I'm reading too much into the background of the photos.

Thanks
Hager

Anyone tried the "encoder" jog built into mach 2?

Eric

Last I read on their forums was that Art was working on it so as to allow multiple encoders, rather than just the one. Not sure how it works though!
I am working on a pendant at the moment which has two 1000cpr encoders built in, but I will interface these using Les Newells "special mouse driver". I haven't got to the technical side yet, but the encoders need to be wired into the decoder part of a regular mouse, then you just plug the mouse into the PC as normal. The special driver is assigned to the mouse, and will only work with Mach2 to jog each axis. With Mach2, this seems to be the preffered option for smoother jog. You know that i am not so good with electronics, so you might want to go look up mpg's on the yahoo group.

One thing I noticed about a machine on ball screws is the axis can now be "driven" by the cutting forces. This alone makes manual machining impractical. You need to lock the axis you are not moving, so it won't move.

Another thing I noticed is this machine likes light, fast cuts much better than heavy, slow cuts. CNC just happens to be handy for that...:)

Eric

Bored the pulleys to the right diameter for the motors (1/2"). I had to make bushing for two because the ID was too big from the factory for the lead screws (3/8").

The x and y will use "L" size and the Z with get the "XL"

Eric

The 3/8" bore on the large pulley seams a bit weak.
You will have to watch your tension on the belt so
you don't bend the tiny shaft.
May have been better to make a sleave for the shaft
instead.

they are 3/8 because I started with 5/8" screws, reduced to 1/2" for bearings, then threaded 1/2" for a retaining nut, then down to 3/8 for the pulley. 7/16 may have been better. The good thing is the shaft will be short. I don't expect there will be a problem.

Eric

A friend of mine is cutting the motor mounts on a cnc machine because they are hard to cut on a manual machine the way I want them. Unfortunately, this is taking a long time.

In the mean time I will be building the control. Stay tuned.

Eric

Since my machine is still manual, I made this tool holder for my QCTP. The one on the right is the factory made one, left is home made.

Eric

I am working on the z-axis turning nut assy. Here it is so far. The nut etc. go in the hole in the head casting behind the quill. The motor ends up on the right side of the head.

I used CAD to figure out the exact space between the motor and the turning nut based on the belt length and pulleys used. It turned out exactly right. No slots were used for the motor mount. If things strech a little I will add slots.

Have a look

Now you are seeing what I went through to design my Z axis setup :)

The guy cutting my motor mounting parts has too many irons in the fire! I let him off the hook and made them myself on my mill drill. See the picture. The ones he was going to cut for my had bigger radii and were a little prettier. This will work fine.

Eric

Now we are talkin...

I got one motor mounted....

Well, not alot of replies here but this thread has over 8000 views so some must be following. I will just keep posting. I know I am finding it hard to get any details on how people did this conversion. Lots of pictures of finished machines.....This is here to help anyone out there trying to do something similar.

X axis motor mount soon....

Eric.

balsaman, I'm definately following. I have a mill/drill also. Not sure if it's exactly the same, but it may be.

I had originally tried to use the stock screws. I have X and Y motors mounted, but have some pretty bad problems with backlash and the screw catching causing the motor jump around. I purchased Jeff D's X and Y plans and plan on starting over when funds are available.

I already have the motors and electronics. Unfortunately, my motors are too large to place up inside the casting as Jeff did. So I'll look forward to more detail on your Z axis.

Something I"ve seen mentioned in your post and also on several others, is 'turning the ball nut' rather than the screw. I've tried to picture how to do this in my head and can't seem to figure out how it would be done. I saw your pictures of you Z axis, but still couldn't figure it out. Care to explain it a little?

Eric,
What ratios are you using for each axis. I have a similar mill that I've been thinking of CNCing. Source for your timing pulleys and belts would be cool.

Thanks,
Paul

That mill is a little different than mine. Morse taper instead of R8 spindle, 4.5" column instead of 4.75". Other specs. are similar.

Same motors as I am using. I hope they work. I should mention that any all of the above posts are just my best guess as to how I think it should be done. No guarantee I am doing anything right. As this thing gets closer to completion, I will let you know if I made the right choices. Most of the time I use the TLAR method of engineering. Very few actual caluculations going on here. In the past this method has served me well.

Eric

balsaman, I'm definately following. I have a mill/drill also. Not sure if it's exactly the same, but it may be.

I had originally tried to use the stock screws. I have X and Y motors mounted, but have some pretty bad problems with backlash and the screw catching causing the motor jump around. I purchased Jeff D's X and Y plans and plan on starting over when funds are available.

I already have the motors and electronics. Unfortunately, my motors are too large to place up inside the casting as Jeff did. So I'll look forward to more detail on your Z axis.

Something I"ve seen mentioned in your post and also on several others, is 'turning the ball nut' rather than the screw. I've tried to picture how to do this in my head and can't seem to figure out how it would be done. I saw your pictures of you Z axis, but still couldn't figure it out. Care to explain it a little?


I will post some better info on the z-axis. At this point I am wondering why I didn't use the existing fine feed. Too easy I guess. :)

Eric

Eric,
What ratios are you using for each axis. I have a similar mill that I've been thinking of CNCing. Source for your timing pulleys and belts would be cool.

Thanks,
Paul

2:1 ratio. I will post actual tooths and details etc. this afternoon once I dig out that info again.

Eric

A little more detail for the z axis.

Here are the first parts I made for my rotating nut assy. Aluminium, bored out to .75". The bakll screw goes inside. The coupler connects the ball nut to the tube. The collar you see is machined in. It takes the thrust loads.

Here is the rotating assembly assembled. No screw in there yet. This whole assembly is captured between two plates that are counterbored to accept the angular contact bearings. Click on the picture to enlarge....

That makes much more sense. I guess the 'a pictures is worth a thousand words' saying is true.

Now all I need is a lathe.

Thanks balsaman.

hello Balsa Man
Did you get the
one of E4-250-125-H-PKG1
then
2 of E4-250-125-H


Got a chance to play weight lifting the box of servos weighs 99 Lbs
I ordered 4 2100 rpm 50Volt motor
got 2 with 1/2 dia shaft and some kind of drive ring on it
part # 116150-02
also 2 with 5/8 dia shafts that has a set screw in the end that expands the
end the end of the shaft has 3 splits
part # 116150-01
kind of like them better than the 1/2 inch shaft ones ?
want to buy pullies but what size both?1/2 5/8

Mine are all 1/2" shaft. The pulleys I bought had 3/8" holes. I bored them to fit.

Eric

Part numbers of my pulleys and belts are:

For x and y axes:

12L075 (12 tooth, size L, .75" wide) and 24L075 (24 tooth, size L, .75" wide) pulleys and 165L075 belt (165 tooth).

For Z axis 20XL037 (20 tooth, Size XL, .375 wide) and 40XL037 (40 tooth, Size XL, .375 wide) pulleys and 160XL037 belt (160 tooth)

They are made by Martin Sprocket http://www.martinsprocket.com/ but I bought them locally.

Once again I am not saying these are the best ones to use but are the ones I am using.

Eric

I am not sure how many amps these motors need. The nice thing about one PS for all motors is that rarely do all the motors draw current at once, so you have extra current to one motor when it needs it. For example if the motors are 5 amps each, you could probably get away with a 10 amp supply. I am building an unregulated supply good for about 20 amps at 50 or so volts.

Here is another shot of the y axis mount since the first pictures didn't really show the shape of the aluminium parts.

Here is the x-axis mount....

I ran the motors on 12 volts to see the axes move. At that voltage, while not blindingly fast (maybe 30" per minute?), I could not stop (or even slow) the axis with any part of my body leaning into it. At 50 volts these motors will break something in a crash. I will definately add limit swtches.

balsaman, I read earlier in this post something about losing a few inches in X travel. Have you figured out exactly how much you lost? Also, couldn't this have been prevented simply by rotating everything so that the motor was actually above the table?

Check out MPJA.com, I have gotten all my transformers from there lately, I have 5 of their 24v 10a transformers :eek: 2 of them in series on my mill, will be running 1 on my lathe, and for temporary uses, ill be putting one on my mills A axis

I have really liked these transformers, Im running 3 steppers set at 4.5A each and without active cooling the two transfomers are hardly warm.

Youll find most of the other stuff you will need there too. I bought my energydrinkcapacitor off ebay, 18k uF 80v.

I am not familiar with servos, do you set the current on them similar to steppers?

heh, you dont need limit switches;) i have watched my machine crash into the extents of travel so many times to carelessness in jogging at 160ipm on 3.5" travel. Just one of those things I wish I had the room for:)

Do you have plans for home switches on there? Those are one thing that I can strongly suggest, I recently installed my x and y axis home switches and oh boy is that ever nice not having to edge find the vice and stop every time I turn the machine on.

About the power supply situation, I would give it some overhead, you may run into those projects that use all 3 axes, I was recently milling holes and instead of plunging every time around I just milled a helix and finished it at the bottom.

Is it possible on the servos to use the voltage and resistance to calculate the current? I havent had electronics class or done too much of that for a while to remember.

Jon

balsaman, I read earlier in this post something about losing a few inches in X travel. Have you figured out exactly how much you lost? Also, couldn't this have been prevented simply by rotating everything so that the motor was actually above the table?

Not sure exactly how much. Maybe 2". Yes, you could mount the motor above, but if you had a long part on the table the motor would be in the way. Also, it's harder to protect the motor from swarf, coolant sticking way up there. My travel is limited by the fact that the motor mount hits the edge of the ways. That"s a long ways over on the table. All designs are a compremise.

Eric

With servos the current follows the load. High load = high current, low load = low current. No need or option to set it on the drive.

Servos develop lots of torque when stalled. These will break something. :cool:

Eric



Check out MPJA.com, I have gotten all my transformers from there lately, I have 5 of their 24v 10a transformers :eek: 2 of them in series on my mill, will be running 1 on my lathe, and for temporary uses, ill be putting one on my mills A axis

I have really liked these transformers, Im running 3 steppers set at 4.5A each and without active cooling the two transfomers are hardly warm.

Youll find most of the other stuff you will need there too. I bought my energydrinkcapacitor off ebay, 18k uF 80v.

I am not familiar with servos, do you set the current on them similar to steppers?

heh, you dont need limit switches;) i have watched my machine crash into the extents of travel so many times to carelessness in jogging at 160ipm on 3.5" travel. Just one of those things I wish I had the room for:)

Do you have plans for home switches on there? Those are one thing that I can strongly suggest, I recently installed my x and y axis home switches and oh boy is that ever nice not having to edge find the vice and stop every time I turn the machine on.

About the power supply situation, I would give it some overhead, you may run into those projects that use all 3 axes, I was recently milling holes and instead of plunging every time around I just milled a helix and finished it at the bottom.

Is it possible on the servos to use the voltage and resistance to calculate the current? I havent had electronics class or done too much of that for a while to remember.

Jon

If that be the case, roughtly how many amps and volts are you planning to run through those? If you have a general idea, you can just grab a power supply or transformers and the rest to suite your wants and let the drives do the rest no?
If you buy one of those transformers and dont draw the absolute maximum current, you will get about 33vdc off of them after rectified and filtered. You may want to consider an inductor to smooth out the current if it will be seeing sudden loads.

Jon

hello Balsa Man
Did you get the
one of E4-250-125-H-PKG1
then
2 of E4-250-125-H

I would liketo order these is this the order #you used?

Servos develop lots of torque when stalled. These will break something.

Yes you better put Home/Limit switch's on all axis. With my setup I have snapped off 3/8" end mills with no problem. Luckily I have never crashed my mill yet. I have milled to deep and cut a good size chunk out of my vise! The mill did not stop though :D

I got 3 of the E4-250-187 encoders. No H option (hole in the back cover), no PKG 1 option. The 187 is for a 3/16" shaft. I also ordered 3 cables part number CA-3286-6FT.

Please note that these are tiny encoders. Too small to actually fasten the the motors with the supplied screws. I am going to use double sided carpet tape to hold mine on. It may be worth while to get the E2 ones which are a little bigger.

Eric

The goal is around 50 volts DC. The powersupply will be good for 10-15 Amps. I have the transformer, rectifier, and capacitor, geckos etc. etc. I just need to wire it up. I do electrical work by trade so I am procrastinating....Not my favorite chore. Maybe this week.

Looking at it tonight I see that my enclosure is too small to make it all fit comfortably. This means it's gonna be crammed in there or I need to find a bigger box. I also hate the fact that the gecko's adjustments are located on the side of the drive, forcing me to think about how they will be mounted. Either you can get at the little pots., or the terminal strips, but not both. (chair)

Eric



If that be the case, roughtly how many amps and volts are you planning to run through those? If you have a general idea, you can just grab a power supply or transformers and the rest to suite your wants and let the drives do the rest no?
If you buy one of those transformers and dont draw the absolute maximum current, you will get about 33vdc off of them after rectified and filtered. You may want to consider an inductor to smooth out the current if it will be seeing sudden loads.

Jon

Sidecar, to keep things from getting confusing, I slit your conversion off this thread. See here: http://www.cnczone.com/forums/showthread.php?p=62673#post62673

Eric

Thanks
going to get the bigger E2 encoder as you suggested
you putting in ball screws
i noticed servo motor is to big to fit up into the cavaty of the head
I will put pictures up in my thread
please stop by thanks again

Eric... no updates for like 3 weeks... What's up with your conversion as of late? I was enjoying your work log. I'm experiencing withdrawl symptoms. :P

hello nebiew here great site yall have
thanking of making a drill mill convertion just curious would it be easy to just add the stepper motor to the handel of the drill in stead of adding a lead screw. Would a high torque motor work of turing the handel.

Eric, me too. Anxiously waiting more posts!

I am just getting ready to make the mechanicals of my mill drill conversion happen so your log has been a great resource! I have a set of those cutesy little servomotors from Jeff Davis (thanks Jeff!), gecko 320's and transformers are all wired in in the stripped out PC enclosure as per Jeff's plan , so I will be bench testing soon!

I am really enjoying your posts on adapting the mechanical side of the conversion, especially the Z axis. Bearings, pulleys & b'screws are my next step!

Keep up the good work!

markg
montreal

hello nebiew here great site yall have
thanking of making a drill mill convertion just curious would it be easy to just add the stepper motor to the handel of the drill in stead of adding a lead screw. Would a high torque motor work of turing the handel.

Yeah, you could but the problem is with the backlash on each axis...you gotta minimize that to almost nothing (.001) or less. The other item is that ACME's are at their best only about 30 to 40 percent efficient while ballscrews are in the 90 percentile range....so ACME's would require a larger stepper (more torque).

Sorry guys. This will continue in a few days. Stuffs going on that is soaking up my time.

Eric

Well, my Dad had a heart attack and then needed triple bypass. He lives 2000 miles from me so I went down there. All is ok, but then other life stuff was preventing me from getting anything done.

Finally,

Control is shaping up. Here is the progress so far. That's a 1000 VA transformer and a honkin CAP. I get around 42 Volts DC out. Each drive will be fused at 5 amps. Won't be long and this thing will me moving on it's own steam.

For those of you who are waiting to see the Z-axis, you will have to wait a little longer because I need x and y going so I can mill the last parts for the z axis. It will be manual z axis untill I get the parts made.

Eric

I was at the Harbor Freight Store the other day. You really can't appreciate the heft of the mill that you are converting until you are right there at it. I cannot believe that they sell that mill for $799.00 on sale.

anoel, I thought the same thing. When I went to buy mine, I went back to where they had them. Saw it sitting on the floor (guess it was too heavy to put up on their shelf - 600lbs), and said 'no, that can't be it. that's too big'. Would you believe I hauled it home in mini van? hehe

I have mine under power now. Using the stock lead screws. But something tells me they weren't meant to be driven at 100's of RPM (900RPM motors @ 10tpi). Not to mention I probably don't have things lined up right. So it binds a little. Ok, a lot. I actually haven't ran it in over a month because I'm waiting to get all my stuff to convert it to ball screws. I actually have every thing I need now, I'm just trying to get the ballscrews turned.

Hi Eric, glad to see you're back with us and I am hoping your dad is alright.

Quick question about the z axis photos you posted a week or two ago, what bearings did you use? Something like a 3205 double row angular contact bearing?

thanks

Not sure...It's two INA Bearing Co. Andrews P/N B9 angular contact bearings.

Eric

Well folks,

I got x and y axis going today! I interpolated a circle and it's working great with unbelievable torque! Speeds are at around 70" per minute right now. My goal was 100 but I am only putting out around 42 volts to my 50 volt motors. I will leave it for now as it's easier. The table is small so the speed isn't necessary.

This bad boy gets clamped on the quill. It completes the z axis drive. I am just about to turn the z axis ball screw and thread the end to fit a 3/8" hole in this part. The turning nut drives the screw up and down which, via this part, is mechanically fastened to the quill. It's 1" thick aluminium, cut down to 3/4" at the pointy end to clear some other z axis drive parts.

Eric

Here is the z axis assy. Just a matter of bolting it on there now. Maybe soon this mill will have cut a part......:)

Lookin good! Did you manage to fit the servo inside the head?
If not, where does that mount? Also, are you machining your parts on that mill or do you have access to a cnc for those?

Jon

The motor fits outside the head on the left side. Just the rotating nut fits inside the head. All the parts were cut on this mill except the part that fits the quill. It was by my tool and die buddy on a cnc mill.

Hey all three axis are working! Very nice and smooth and too much power! I am afraid to crash this thing. Will have to put the limit switches on soon.

A couple notes:
I messed up on the y axis ball screw. The pulley wobbles a bit. Must not have had it in the chuck properly.

The weak spot on the z axis is the part that couples the quill to the drive. It's posible to cause it to flex (actually slip on the quill) if the motor wants to go but the quill doesn't. Driving the fine feed instead would be much more rigid but lots of backlash and somewhat micky mouseish IMHO. Once I start cutting I will know better. Jeff D what is your take on this?

I measured the BL on the y axis and it's .003". I am ok with that.

I am going to put the handwheels on the x and y axes just to make setup a little easier. Eventually I want to go with some kind of encoder jog scheme.

First cut part coming right up! Stay tuned!

Eric

Balsaman, is the inside of the quill clamp smooth? I wonder if it would grip better if you used some low grit sand paper to rough is up a little.

I was originally going to try and use the fine feed, but when I saw Jeff's design I decided to try that way. Luckily I'm still a ways off from getting started on Z.

looking good buddy

You know you can't have too much power; LOL

Anyway Eric; post a cutting shot once your comfortable with it
Mine has been cutting UBoat propeller blades all day
http://www.modelbarrels.com/files/brassprop.jpg
http://www.modelbarrels.com/files/solderprop.jpg
http://www.modelbarrels.com/files/myuboatprop.jpg

Hmm, First part reveals that I have a long ways to go with machining metals. Surface finish is embarrasing. Lesson learned: Faster speed and feed? climb mill? I need to hang on to the part, not the stock so I can do a finish pass?

Also am getting some extra steps. It was really bad but then I physically seperated the encoder wires from the motor power wires and was much better but not perfect. I notice that the encoder wires are not shielded so I will be doing something about that.

I learn a little more each day.

Eric

try climb milling; needs 30% less power run 25% faster and the cutter will last longer

Balsaman, you dont typically want to climbmill when you have backlash, it gives it every opportunity to make a mess.
Its hard to see that part. what size passes, end mills, stock, and what speeds and feeds?

Jon

.The weak spot on the z axis is the part that couples the quill to the drive. It's posible to cause it to flex (actually slip on the quill) if the motor wants to go but the quill doesn't. Driving the fine feed instead would be much more rigid but lots of backlash and somewhat micky mouseish IMHO. Once I start cutting I will know better. Jeff D what is your take on this? Eric


I don't seem to have a slippage on the quill clamp at all. How thick did you make the clamp plate. I went with 1/2" plate. Are you sure you are aligned with the quill axis? If you don't have your ball screw lined up with the axis of the quill you may with thoes strong motors pull it off. Clamp the quill, and loosen the servo quill clamp and move the quill clamp all the way down using the servo motor. Now hold the quill with your hands and unclamp the quill. Let the quill move down. Is it still aligned with the hole in the quill clamp?

Mine is driven off the rack Eric
The stepper is turning the end where the return spring mounted; i control the backlash by a spring; crude; but it works good
remember this photo
http://www.warshipmodels.com/~SteveNuttall/newlight.jpg

I used a 1" thick plate. It's all aligned quite well. It's plenty strong and rigid for any kind of normal cutting, it's just if it crashes (retract or advance it beyond it's travel limts, for example) it will cock the plate where it's clamped on the quill. It's due to the hefty motors and the 2:1 ratio. I just need to watch it until the limit switches are on there. I will also remove it and degrease it and scuff the quill surface as well as the bracket surface.

Eric



I don't seem to have a slippage on the quill clamp at all. How thick did you make the clamp plate. I went with 1/2" plate. Are you sure you are aligned with the quill axis? If you don't have your ball screw lined up with the axis of the quill you may with thoes strong motors pull it off. Clamp the quill, and loosen the servo quill clamp and move the quill clamp all the way down using the servo motor. Now hold the quill with your hands and unclamp the quill. Let the quill move down. Is it still aligned with the hole in the quill clamp?

Balsaman, get yourself some home and limit switches. If your using mach2, theres soft limits which rock, you can just jog untill the point where you tell the soft limits to kick in and you dont hit your other limits and it just stops for you. Very handy indeed.

If you got enough power, have you considered going 1:1 on those motors to the screw? maybe after you get the hang of the machine a little better, you wont have as much torque but possibly have enough, plus youll double the speed.

Jon

OK, don't laugh at the feeds and speeds.

Cutter 3/16" HSS 2 flute EM,
Spindle was at 400 rpm,
5 IPM,
.050 deep.

I am sure I need to speed up the spindle to as fast as possible, also faster cutting speed as well. I am going to try another part. I used wd40 for coolant. Stay tuned....

Eric

if your cutting alum
run 3000rpm plus if you have it with a 3/16th

I run in metric

definately crank the spindle as high as it goes, if you can get 3000rpm out of it, feed at 10-15IPM at that depth. With that machine I would think you could take a pretty hefty cut even with that small of an end mill, from my experience on my machine, I can take light cuts at about 6x the speed I can take double the depth and I dont burn up my end mills.

Jon

Yeah,

I just cut one at 2500 rpm (max spindle speed) at a feed of 20" per minute. Climb milling. Way better finish even without a finish pass and also way smoother sounding. No coolant this time. Lots to learn. Stay tuned. Thanks for your help.

Eric

Ok, here is something else I cut. Another lesson learned: Use as short an endmill as you can. This one had 1" of flutes (1/4" endmill) and it flexed away from the cut even at 6" per minute. (2500 rpm) (the last part was also done at 2500, not 2000, as mentioned) This flexing caused irregularities, especially when doing the finish pass, where the cutter had varying amounts of material to cut away. Also, even .003 backlash is noticable when cutting a circle. I will add backlash comp in the software.

The diameter is 3.25", 1/2" plate aluminium.

Learning is good...

Eric

Oh....the y axis BL is more like .050 right now. Time to investigate.... No wonder it's noticable :)

Eric

Balsaman, if you're only taking .05 deep cuts, you may want to also try using a 4 flute (I'm assuming you used a two flute). The extra 2 flutes make them quite a bit more rigid.

it will keep you on your toes for a while

Hmm, the nut on the lead screw against the tapered bearings for the y axis backed off leaving me with plenty of backlash. All tight now with a nylock nut so that should improve things quite a bit. No measurable backlash now.

I will try an 4 flute. Thanks for the advice.

Eric

I use 4 flute mills as well. Much better for the RPM we have on the drill/mills.

Well,

I redid my cabling using all shielded cables. Much better. I still loose (or gain) a few thousands over a few hundreds of moves. Not noticable for the most part but still bothersome. The only cable that is not shielded is the parallel cable. May have to try that one too. I know it was the source of some extra steps on my cnc router.

I have made a few cool widgets. I need to buy more material now because I used up what scraps I had playing around. I have plans for steam engines and IC engines etc.

Overall I am happy with the performance. Fast, light cuts with high spindle speeds work best in aluminium with the smaller cutters. Finish is OK, especially if I can take a finish cut. So far the coolant has been compressed air. Sometimes WD40. The air is mostly to clear chips to avoid recutting them.

I need to add an E-stop button and probably a relay to start/stop the spindle. Right now I keep my hand on the escape button on the keyboard. Haven't had to use it yet. I got past most of the stupid mistakes on my cnc routers. It almost always goes where I expect it to now. :)

Hopefully I will be able to share some of the goodies I cut out and some of the projects I undertake. The plan is to put a web page together.

Thanks for all the help and advice you all gave along the way. Hopefully this thread was a help or inspiration to someone. That is what it's for.

Eric

it is very satisfying is it not

I love watching mine make stuff

Looking good:) Yes, you shoudl get a shielded parallel port cable, thats probably where the communication is comming from.

Jon

Indeed, thanks a bunch for letting us look over your shoulder as your project has progressed Eric!

Please also let us know when you've had a chance to make some bits and the planned web site is up .

Mark
Montreal

Eric,

Could you run your Mill and CNC Router off the same PC/Stepper Drivers, at different times naturally?

Yes but, I sold my router to finance this project. Also I have limited room.

Eric

Here is a video of my cnc mill/drill:

www.ody.ca/~envanandel/cncmill.mpg 13 MB - lower quality

www.ody.ca/~envanandel/cncmill3.mpg 33 MB - better quality

Eric

looking good buddy

did you spray some varsol or some other lub as a cutting fluid?

No. That was cutting dry. I have used WD40 but it makes such a mess....

Eric

I know what you mean; but cutting Alum dry is going to bust your cutter one day; it is very sticky and will gall up in the flutes at some point
Varsol is cheap and just drys off

I stopped making barrels from Alum because not only the mess; but it screws my edge up for brass

Eric, what did you ever find out about the motor current?

Also, have you looked into misters? if your in a decently ventelated environment they work great, they dont make too much of a mess.

Jon

Looks good balsaman!

Nice work Eric. It's to bad you could not have kept your router as well. I like having both. So what kind of work are you now going to schedule for the mill?

I have my first aluminum mold I want to make on mine, and shoot plastic in it with an injection machine I'm going to make from the Gingery books collection.

Jeff, how is that book? I've been curious about that one for a while. I'd like to know if all of the parts are available or at least buildable without a huge amount of effort.

They blow 5 amp fuses but not 10. So somewhere in that ballpark... They seem to be working very well.

Eric


Eric, what did you ever find out about the motor current?

Also, have you looked into misters? if your in a decently ventelated environment they work great, they dont make too much of a mess.

Jon

I had a persistant problem with what I thought was noise causing position errors. I changed to shielded encoder cables which helped but did not eliminate. After much frustration I discovered my encoder disks were too close to the sensor in the encoder. It caused missed/extra steps. Just a few thousands here and there but enough to drive me crazy. Moving the disks out on the shaft a bit fixed it. The encoders came with a plastic spacer for setting them up but I didn't bother with it. I always seem to learn the hard way. :)

I have not missed the hand wheels. You guys were correct I hadn't needed bother to try to encorperate them.

I am building a twin cylinder steam engine. Check that section shortly for a build log....Many parts will be cnc cut!

Eric

Since I got my position error all worked out I did some tuning today. I changed the tap in my power supply transformer to get 51.2 VDC out up from 40 volts. I increased the rapids up to 100 IPM and the accel as well. It's working very nicely.

Someone at CAD_CAM_EDM_DRO said these particular motors were no good for servo application. Probably one of those "experts" who has never actually built anything in his life :).

Turbocnc V4.01 is powering the machine. A lot of effort has gone into this software and while it's not perfect it's getting to be very good. The rumor is that cutter radius comp. is coming soon as is constant velocity contouring. The price is right and it runs on old computers. Mine is a Pll 233.

Eric

Jeff, how is that book? I've been curious about that one for a while. I'd like to know if all of the parts are available or at least buildable without a huge amount of effort.


The machine is documented very well in the book. I don't know if the parts are still available from the sources listed in the book now. They were available a few years ago when I ordered the parts. (parts still sitting on the shelf). I think the only parts that may be hard to find would be the heating element. I ordered two of them because I am going to make my heat chamber larger for larger shots. The oven reostat (spelling) is the other part. That I think can be found somewhere else.

balsaman,

Did you get the backlash corrected in your system?

Which ballscrews and nuts did you end up using....I see that you used 5/8 inch ballscrews for the x & y-axis and you had a 2:1 ratio for your timing pulleys to servo interface.

Yes and no. I got all of the slop out but there is still .004 in the system even tho I got the nuts loaded with bigger balls. I was hoping for better than that. A couple of those thou might be from the timing belts??, the rest is in the ball nuts. I may buy two more nuts and make them preloaded.

Yes I went with a 2:1 ratio which is perfect IMHO. I bought the screws and nuts from www.roton.com

Eric

balsaman,

Just wondering how you're measuring the 0.004, I'm wondering because the accuracy of your ballscrew are +- 0.004. Do you notice that when doing an operations? Thanks, Paul

If I move the axis some distance and back it's .004" from where it started. This measured with a dial indicator. This is consistant and not cumulative. The .004 acuaracy you mention is .004" over 12" of ball screw. This would mean if I went 12" I may be out up to +/- .004. I have not checked if this is true. I could atatch a digital vernier and go 6" and check I guess.

Is the backlash noticable? Yeah, if you measure the part with a vernier. I could try and dial it out with backlash comp but in my experience this just creates funny looking parts. For the parts I make I can live with .004 baclash for now. There are also errors from spindle runout (unmeasured at this point), slop in the quill (also unmeasured), and tool deflection, so backlash is just one issue, and I doubt you can do much about quill slop.

It's a $1000.00 mill after all.

Eric

I would lock down the table use a dial indicator and using the hand cranks go clockwise and then counterclockwise....that will show you the amount of backlash between the ballnut and ballscrew.

What I have been doing is use a DTI and jog my machine incrementally untill I get it exact.

although even then I havent been cutting perfect circles, so what i did is adjust the backlash accordingly to cut them as perfect as possible. I will be sending my ballscrews and ballnuts to homeshopcnc(I think thats the site) to have them preload my nuts with larger balls for $35 each(that is me supplying the nuts and screws)

Jon

What sort of backlash are you currently seeing?

Eric


What I have been doing is use a DTI and jog my machine incrementally untill I get it exact.

although even then I havent been cutting perfect circles, so what i did is adjust the backlash accordingly to cut them as perfect as possible. I will be sending my ballscrews and ballnuts to homeshopcnc(I think thats the site) to have them preload my nuts with larger balls for $35 each(that is me supplying the nuts and screws)

Jon

Way too much. In my Y axis, I measured about .0065 but I have it set up around .008 for cutting perfect circles, the X axis is good though, .0015"meassured but set at .0025"
I have y z-axis preloaded so I dont have any problems there.(theres actually room there:))

Jon

eric & jon, This is all valuable information that will certainly help the rest of us determine how to proceed. Do you both have the RF30 equivalent round column mill....I have a Jet JMD18 (RF30 equivalent) that I was considering CNCing.

I have a sieg X2 mini mill from homier.com(they no longer have them)

If I had room for one of those RF30 equivalents I would have one;)

Jon

I got lucky this weekend and found a used Plll 450 for $25.00 CAD. Installed XP and Mach2. Couldn't get my z axis working no-how until I finally changed the parallel port from bi-directional to ECP in the bios. Man, that Mach2 is nice software....I have been a turbocnc fan but I think I've been converted.

Eric

oh wow does mach2 rock man.
I am upgrading my computer from a 700mhz celeron to a athlon xp 2500+ hoping to hit 200ipm:)

How many pulses does yours put out? my 700mhz system puts out 26000 for mach2, I installed mach2 on my server and it was putting out 46000, so I am hoping that I can do that with my mill:)

how fast are you able to get that thing moving?

Jon

25 Khz max. My machine goes up to around 125 IPM which is scary fast. I have it set at 100 IPM which is 16.66 Khz. Mach2 is very slick. Smooth motion. The wizards are pretty cool too. The guy is a genius. I will be sending my money to Art shortly.

Eric



oh wow does mach2 rock man.
I am upgrading my computer from a 700mhz celeron to a athlon xp 2500+ hoping to hit 200ipm:)

How many pulses does yours put out? my 700mhz system puts out 26000 for mach2, I installed mach2 on my server and it was putting out 46000, so I am hoping that I can do that with my mill:)

how fast are you able to get that thing moving?

Jon

Hey balsa, I have similar machine fr. H.F. Did you find any slopp in the spindle sleeve when tramming. Mine has about 2-thous. slopp when locking the spindle sleeve. If so it would seem like the clamping piece thats included in the z conv. could fix this a bit.

I have not measured the slop in the quill. I suppose there is some...

Eric

I made some fixed hieght tooling. Started with 6, 1.5"x3.125" lengths of brakedie. Turned one end to .750, turned it around and put it in a 3/4" MT3 collet and turned the od as shown and bored for the various sizes endmills. I have one more to make and I need to drill and tap the set screws.

Next I plan on grinding a standard 3/4" R8 collet shorter so that the flange on the new tooling will be pulled up against the quill as the collet gets drawn into the taper. This way the tool z hieght should be repeatable between tool changes.

The plan is to make use of the tool length offset table in Mach 3.

Eric

I don't think that will work; well not to within a few thou

why?

Balsaman, I made some similar ones like that a while ago and a few nicer ones now. The problem you run into is runout. when you bore them its not as much of a problem though.

You do need to machine them in a collet for sure but even then you run into runout.

The largest end mill you want to use in those is a 1/2" end mill, then for a 3/4" EM I made a little collar that acted the same that I use for that and bigger cutters so they are fixed.

Another thing you must do is grind a flat if there isnt one, if you dont, your set screw may gouge your end mills(hss) and in turn wreck your holders.

To make them press up gainst the noze of the spindle, you turn a little recess with a face grooving tool, I made mine out of a HSS blank and it worked good.



Jon

forget it; I'm thinking like a tool and diemaker again; to me 2-4 thou is roughwork; sometimes I forget this is home stuff and they don't need to be dead on
I was thinking about my post while I was seting up the Y axis mount on the Gantry mill
and thought it will most likely be ok

Hi Jon

I was thinking the same; and the height will be a bit of a problem too; but not as much as the runout

Me and a guy who works at the main plant (I manage a small grinding div) might be making a small cat taper holder range just for home use; maybe a 10 or 20 size

ya, there will be a bit of runout. I did bore the larger ones and reamed the smaller ones. I do have flats on the endmills.

The z should be close because the flange of the holder will push against the spindle nose.

I'll measure the runout once they are in the spindle.

Hi Eric, just wondering how hard is "brakedie"? I made a set of these for the router some time ago and they worked well. The only problem I found was that if you crash the tool, the toolholder becomes ruined. Mind you, I was using plain un-hardened silver steel for the holders. The thought of the steel warping during heat treatment always put me off of hardening them, you got any thoughts on this?

Like any pre hardening process; you need to allow for movement during HT
I usually leave 0.01-0.005" for finishing after HT
If you use 4140 pre hard; you can use it in light duty stuff without any HT

I have HT myself many times with good success; the thing to remember is to quench in oil; never use water; the shock is too great and micro stresscracks will be started

A good O1 grade steel will give you good results

I've been a tool and diemaker for going on 37yrs (4 for the app/ship)
I'm allways open to questions

Drill rod; cheap and easy to find; will harden quite nice; you can use it right from HT without needing to draw it back a bit; or if you want to; just go light straw color and quench (water for draw quenches) you will still need to post machine to be dead on concentricity; but the movement will not be great; I've even had it swell; and ended up with more to remove from the diameter; but the length did lose some; the molecules had to come from somewhere LOL

I think it's 4140 pre-heat treated. It's toughter than mild steel but was not problem to machine on my little lathe. Nice finish and chips when I took .080 to .100 of the od (max for my lathe), but not as nice on any finishing passes.

How did you ruin them in a crash? Did they bend?

Eric

Eric

Punch the speed way up and it will finish nice with a 25-32 thou rad insert

Eric, the bore got enlarged, only by a fraction, but enough to introduce extra runout or even wobble. Bear in mind most of my old cutters were less than 1/4" dia, so they press into the steel easier.
Stevie, thanks for the tips, perhaps one day eh!

Eric

Punch the speed way up and it will finish nice with a 25-32 thou rad insert

Thanks Stevie. You may have been a tool and die maker for 37 years but you have the enthusiasm of a teenager! :) I like your projects.

Eric

Eric, I have just through the thread again, looking for how you handled the y-axis ballscrew. On my mill, there is no rear support bearing, so I was wondering if you had one in there, or whether you left it floating? Thanks, Jason.

floating

I have a ball screw with LH and RH threads; I'll be cutting it in 2 soon; the problem is it's a 2" pitch with 2 starts and dubble ball nuts; with one nut usable travel would be about 14"; it could make a nice gantry setup; with a common drive centered and the opp threads working together one on each vertical
THe speed would be huge with a 2" pitch; so I'm thinking it will be of little use to me; but some router guy might just love it; it is a ground thread version; brand new; if the 2 nuts are used travel would be just over 10" I think
Anyway I'm rambling on here; these would be used as floating also; or if needed i could grind a bearing diameter on the cut end; I think it's a 1" diameter; not sure it's at work right now (for cutting)
If anyone could use such a pair of high speed ground ball screws let me know?

Thanks Stevie. You may have been a tool and die maker for 37 years but you have the enthusiasm of a teenager! :) I like your projects.

Eric

One day if your passing through Sarnia; you'll have to drop in!!

Steve

I just scanned through the entire forum, and I have to say I am impressed by all of you. I recently purchased an OLD Bridgeport mill for home use, and will be planning out a CNC Conversion. I can't help but thank all of you for your wonderful information, and I hope that it goes much smoother thanks to all of your good ideas.

Glad we can help!

Eric

I just went thru the entire thread on this project and I am also very impressed with the knowledge I gained. You can bet I have saved a set of notes for my Harbor Freight gearhead (round column) mill conversion project. I am especially gratified at the openness exibited by all the contributors, it is nice to see that I am not the only one boring holes in the vise during the learning process.

I congratulate Eric on a job well done and I appreciate the extra effort to document this project for the rest of us. ------ THANK YOU! ------

I have the same motors, I will mount the encoders on the end of the ballscrews and use preloaded double nuts on the X and Y axis to help control backlash.

MikeAber

There may be a solution to round shaft alighnement. The Urwhick metalmaster had a round column with a patent, triangular key and key way. This eliminates alighnement problems.

http://groups.yahoo.com/group/Urwick_MetalMaster

Let me know if this helps, Matthew

I have read all the horror stories about the round column mills and the PITA when you need to reposition the head on the column. My question is, if I can live with the 5" quill travel, does this mill do a good job machining with the quill extended?

What are the odds that I can build some sort of external keying (using THK rail and bearings) into the round column and move the whole head up and down on the column as a z axis? If not that, perhaps I can still use the quill for z but use the keying to keep the head in position on the column when manually moving the head?

What do you think of using the stock lead screws? I am considering the Mcmastercarr 5/8" rolled ballscrews but are they any better than the stock lead screws as far as acuracy is concerned? I know they would be more efficient. Also If I used two ball nuts for preloading will they bind because of the fact that the screw is rolled and thus not that acurate?

Anyone with experience out there I would apreciate your feedback!

Eric[/QUOTE]

Ok, I am about to embark on a Enco style round column mill-drill conversion.

This one specifically:


Hi

Just joined the forum, thought you might be all posh with lasers and such, but the very first thread I read is about something that looks suspiciously like the one I'm doing :)

http://www.robinhewitt.net/cncmill.jpg

I'm a newby to this cnc lark, just discovered that after 25 years cutting uphill I'm suddenly supposed to switch direction, sounds horrendous :eek: :)

best regards

Robin

Eric,
I also have a round column mill and have planned to secure the rack with
bolts & roll pins (split pin, spring pin).
This seems the shortest & easiest solution to round column movement.
The drilling of the hardened material will be the worst part of the project.
Good Luck.

Tim

No need to secure anything with pins etc. just tighten it up and it won't move.

There is too much play between the rack and the slot to provide any accuracy for head movements.

I just set the head once before the job starts, and have managed to get stuff done despite the round column drawbacks. One solution is to buy a set of screw machine drills (short). Then turn the shanks down to standard collet sizes and forget the drill chuck.

The other thing I do is have the mill bore fussy holes to .020 under size with an endmill using a helical tool path then ream to size on a standard drill press.

Basically, if you can figure out how to drill the holes using short tools, you rarely need to move the head up and down during a job.

Deep holes is another story. Then I use the mill/drill to start or centerdrill the hole, and finish it on a drill press.

Eric

I have back the raising handle off after using it or the rack rattles against the column :D