I previously posted this info in another thread. However, since I am now working on my conversion in earnest (I got my router running). I thought I would go ahead an start my on lathe thread.

Here are a few pictures of my variable speed conversion.

I used a Pacific Scientific DC motor that had a shaft the same size as the OEM Emerson motor (5/8"). This allows the use of the original pulleys and belts.

I made the motor adapter plate from a piece of 3/8" aluminum and a piece of 3/4" aluminum. I used a round-over bit to mill the recess for the motor.

I made the controller bracket from 1"x1"x1/8" HR steel angle. It bolts to the same holes as the original switch bracket.

I bought the Dan Foss C150 controller on ebay. It is currently using a pot to control the speed but it supports a 0-10v DC signal to control the speed. This can be obtained with the use of a board like the Digispeed boards from Homann in Australia.

Alan

Here are a couple pictures of the power supply that I am building for my 9x20 CNC conversion.

I designed a power supply board to make building power supplies easier.
The first photo is a picture of the PS board. The second is the components mounted on an aluminum chassis that I formed at a friends shop.

My ps chassis has my PS board, an Antek toroid transformer 23V 400VA to provide power, a 35,000uf 80v filter capacitor, (2) Superior Electric SS2000MD4 drives, and a CandCNC mini-io breakout board. It outputs about 32V dc at around 16amps. Should be enough??

The power supply board has a full-wave bridge to rectify the AC, a surge limiter to keep input surge from doing bad things, a bleeder resistor, connections to the filter capacitor, and four fused outputs to the drives.

For the lathe I only installed two fuse holders and two drives. I plan to use 2 PacSci 253oz. steppers, one to drive the leadscrew, and one to drive the crossfeed.

Alan

This part of the project originally began as a bearing support modification to the crossfeed leadscrew. I was never happy with that part of the design. It had a bronze bushing in the back end and a single ball bearing in the front end. For a manual screw it would have probably worked fine, but it always nagged at me. I had thought about several different schemes for mounting double bearings at the front end to take out any backlash there. One day I decided to just do it.

I turned off most of the pocket for the front bearing. Then I cut another piece of aluminum and cut the remainder of the back bearing pocket in it. Then I flipped it around and cut the front bearing pocket in the opposite side. So the back bearing aligns the front part of the bracket with the rest of the body and together they support the screw radially and act as angular contact bearings.

Next step was to design a method of driving the crossfeed with a stepper.

Alan

Looks good. Are you planning to use a ball screw and ball nut on the Z axis?
Like your X-axis hardware, is that the stock screw? I cnc'ed a 9X20 last year and it had a 16tpi acme that performed ok with about 200in/oz.
Ron

Looks good. Are you planning to use a ball screw and ball nut on the Z axis?
Like your X-axis hardware, is that the stock screw? I cnc'ed a 9X20 last year and it had a 16tpi acme that performed ok with about 200in/oz.
Ron

Yes, I am planning on using a ballscrew on the Z axis. I have a 6' length of 5/8"x5tpi ballscrew and a double ball nut.

My X-axis has an extra 3/4" of travel. I replaced my original crossfeed lead screw with a 7/16"x20 leadscrew. The new crossfeed nut has an adjustment to reduce backlash. Eventually I hope to replace it with a ballscrew as well, but I haven't reached a final design for that yet. I am leaning towards a rotating ballnut and fixed ballscrew. That would allow me to have the crossfeed ballscrew in the original tunnel.

Alan

Once I figured out the manual bearing support setup for the crossfeed, the CNC drive was easy. I took a piece of 3/4"x4 aluminum bar and figured out the center for a 60T .2 pitch belt gear. Next I figured out the center location for a M23 Stepper motor.

I machined front and rear bearing pockets to match the bearing pockets on the manual bearing support.

Then because the stepper shaft was too short to go clear through the 3/4" material and support a belt gear on the other side, I milled a pocket on the reverse side to set the M23 stepper part way through the plate.

Now I have to figure out the belt tensioner.

Alan

I took the spindle apart because I had read that part of the finish problems that I have had over time could be because of the spindle bearing adjustment. I had to drive the spindle out with a hammer and a block of hardwood. When I mic'd the rear bearing journal, it was 1.3780. I mic'd the inside of the rear bearing and it was 1.3776. I also checked the inside micrometer against the outside micrometer and they were in agreement. I chucked of the spindle in my other lathe and used a fine flat file and some 400 wet or dry sandpaper to achieve a snug sliding fit.

Then I discovered that the gear and pully wouldn't slide on either. There, I discovered that the key didn't want to come out of the spindle slot. I finally clamped vise grips on the key and used a brass hammer to tap the vise grips. It took about twenty tries before I finally got the key loose. Without the key in both the gear and the pulley were an easy sliding fit. So, I dressed the sides of the key until I could hand press it in and pull it back out with pliers. Then everything would go together properly.

I cleaned up the bearings, greased them with "Super Lube" a teflon bearing grease. I put it all back together and adjusted the fit.

Now I need to cut something to see if it improves the finish.

Alan

I know that I ultimately don't need the DRO after I have it CNC'd, but I need it right now. So I am trying to mount my Shumatech DRO-350 on my G4000 as a temporary measure.

I already had the DRO, QC-100 quadrature to chinese signal converters, USDigital encoders and encoder strips(7" and 22"). So it is a question of mounting.

I took a small piece of delrin and machined a holder for one of the encoders. I machined a slot into the holder so that it would slide on the edge of a piece of 1" square aluminum that I cut a 0.625 slot in the bottom.

I still need to mount the linear encoder strip in the aluminum tube and mount the whole thing to the cross-slide. Then I have to do the same thing for the bed to carriage encoder.

Alan

Nice job! :)

twocik,

Thanks for looking, I am reworking the encoder mount/slide. I am trying to resolve interference between it and the gib adjusters on the crossfeed.

I thought about mounting the encoder on the chuck side of the crossfeed but then it limits how close I can get to the chuck (while at the back it limits how close you can get the tailstock to the crossfeed). It makes some of the ideas about using a cable driven encoder sound enticing. Oh, problems, problems. Well a new tailstock design would solve that, but I promised myself no new projects till I finish those already on my plate.

Alan

I got the encoder carrier redesigned. Now it has slots for slides on both sides and it will clear the gib adjusting screws on the cross-slide.

I got some 3/8 x 3/8 ground stock to mount the encoder strip. I am going to machine a couple of delrin plugs so that chips can't enter the ends of the square tube. Then I have to fasten the encoder strip to the 3/8 x 3/8 spacer. Then I will have the first tube done. I want to hook it up to the DRO and test it before I mount it on the lathe.

Then I still have to cut the slot in the Z-axis tube, put the Z-axis all together and mount everything on the lathe.

Alan

I have been working on a controller that will allow the lathe to work in manual mode (no gcode) using the cnc electronics. I designed a small circuit board that has two modes. The first mode acts as a variable speed automatic feed and the second mode uses an encoder to generate steps as the handle is turned. You can select either the X or Z axis in either mode.

Alan

I used one of my optical switch boards to feed the tach on my DRO-350. With one of my little PacSci steppers and my "manual" controller I can vary the speed from 252 rpm up to 3072 rpm before the motor shuts down. Some of my other steppers shutdown at about 600 rpm.

I think I am going to adjust the speed range down. I am looking at something like 15 rpm to 1500 rpm. With my current gearing this would give me feeds from about 0.187 ipm to 18.75 ipm. Does that sound OK? Or is it still too high?

Alan

I've been busy with other jobs but I finally got a few free minutes. When I put the stepper plate on the crossfeed, the belt was loose on the pulleys. I had not designed in any adjustment, but I had thought about the solution. I had a little adjuster that I got off of another stepper I bought on ebay. So, I machined a pocket for it to sit in and voila "instant adjustment".

Next step is to figure out the Z-axis screw. I thought about leaving the stock lead screw there but I have a number of double ballnuts and a 6' length of ballscrew, so I think I will go ahead and replace the standard lead screw with a ballscrew now. Eventually I plan to replace the crossfeed screw with a ballscrew as well.

Alan

I decided that the best way to deal with the Z-Axis was a ballscrew and that the best way to do that was to machine an end to attach to the ballscrew that would fit through the bearing block and connect to the motor. It has a 0.500 bearing surface with a 1/2x20 adjusting nut and a 0.375 connecting end. I also need to shorten the connecting end shaft by about 0.25".

I am using an existing Nema23 motor mounting plate, but I had to make new hexagonal standoffs because the ones I had were too short for the adjusting nut and the lovejoy connector. The new standoffs are 2.5" long and both ends are drilled and tapped 10x32.

The bearing support will fit in the same location as the stock bushing for the stock leadscrew. Now I have to cut off a section of ballscrew, anneal the end, and turn it to fit in the end of the fitting I made. I am thinking of attaching it with silver solder. Is that a good idea or not? I could braze it or pin it but silver solder is not quite as hot as brazing, less chance of warp, I think.

Next I need to decide how to mount the other end. I am thinking about annealing it and turning it to fit into the hole where the original leadscrew connects to the standard gear box. However, I could just build another bearing support to mount to the bed. Any suggestions.

Finally, I am planning to remove the existing carriage that attaches to the saddle and attach a plate to which to mount the ballnut.

Alan

I left my gear box alone and just turned that end of the screw to a couple of thou under the size of that mount fixture for the original screw and just let it turn inside there. No problem to date.

On the adapter, you could turn the end of the screw to about .002 larger than the pocket you've built and press/drive it home. I've had good luck doing that cold. For a firmer joint , make the shaft a bit larger then cool the shaft with dry ice and heat the pocket then press them. The wheels on rail cars are attached to the axles with this exact process....no weld or solder!
jb

I left my gear box alone and just turned that end of the screw to a couple of thou under the size of that mount fixture for the original screw and just let it turn inside there. No problem to date.

That is where I got the idea.

On the adapter, you could turn the end of the screw to about .002 larger than the pocket you've built and press/drive it home. I've had good luck doing that cold. For a firmer joint , make the shaft a bit larger then cool the shaft with dry ice and heat the pocket then press them. The wheels on rail cars are attached to the axles with this exact process....no weld or solder!
jb

John,

Thanks, I read that on your thread before but had forgotten about it. It sounds like it might be worth trying. Although I live in a small town and I am not sure about the availability of dry ice.

Alan

Frankly, Alan, the cross feed screw on my lathe took no ice or heat and has never slipped.
The purpose of heat is to expand the size of the hole and reverse with the cold. It will shrink some in your fridge or freezer and expand on the BBQ.
Heck, give it a try! The worst that can happen is that you learn from the experience. If you botch it completely, you can always braze it or even spot weld.

That reminds me check this out! Post#5
http://www.cnczone.com/forums/showthread.php?t=29339

Well I took John Howell's advice and turned the end of the ballscrew about .002 larger than the pocket in the end piece. Now I just have to find some dry ice to chill the end of the screw.

Alan

Looks like a nice job on that screw, you might just ride the leading edge with a file for a taper to help get a start. I think you'll find putting the two together will be anti climatic. I've come to rely on this method a lot!!

John,

I did that before I took it out of the lathe.

Alan

Well, I used the tailstock on my 12x36 lathe as a press and pressed the machined end onto the ballscrew. I had left it 0.250" long so that if I dinged up the end, I had room to clean it up. When I was done pressing it on, I turned of the extra length.

I had cut the screw about 0.500" long so I parted that off and then I turned the end of the ballscrew to fit into the hole for the original leadscrew on the gear box.

Then I did a test fit to the lathe. I stuck the end in the gearbox stub, mounted the motor end bearing support, and bolted on the carriage plate.

Next step is to layout the ballnut mount for the carriage.

Alan

NICE looking job, my friend!
In as much as you were able to turn that part in your lathe I assume your joint was snug?!
MMMMMMMMM, I love when things WORK!
jb

NICE looking job, my friend!
In as much as you were able to turn that part in your lathe I assume your joint was snug?!
MMMMMMMMM, I love when things WORK!
jb

So snug at first that it wouldn't turn without turning the gearbox shaft. I took it back to the lathe and took a couple thou off. Now it will turn without turning the gearbox shaft, however, it does turn with the gearbox shaft when I turn on the lathe. I will remove the drive gear before I actually try to drive the screw with the stepper.

I am thinking about turning it down a little more and fitting it and a bronze bushing in the end of the gearbox shaft. What do you think?

Alan

Well, I was making reference to the press-fit joint on the stepper end of the shaft, looks like a roaring success.

As to the gear box end, I've had no trouble with just a sloppy fit but I have no intent to ever again use the gears. I just let that fitting eliminate whip from the ball screw.

If friction is a concern and if you want to be able to drive the screw from the box, an oilite bushing with a cross pin hole drilled to match the one in the socket. Of course then you need a hole in the shaft.

A simple set screw pressing against a flat on the shaft might do it too.

Any way, good job!!

Well, I was making reference to the press-fit joint on the stepper end of the shaft, looks like a roaring success.

As to the gear box end, I've had no trouble with just a sloppy fit but I have no intent to ever again use the gears. I just let that fitting eliminate whip from the ball screw.

If friction is a concern and if you want to be able to drive the screw from the box, an oilite bushing with a cross pin hole drilled to match the one in the socket. Of course then you need a hole in the shaft.

A simple set screw pressing against a flat on the shaft might do it too.

Any way, good job!!

John,

Yeh, the press fit was a piece of cake. Although, I actually tapped it on the last 0.1 with a brass head hammer, because the tailstock was sliding away rather than driving the end on the rest of the way. So I guess it is not going anywhere.

I wasn't thinking about driving it from the gear box end, I was just thinking about it turning smoother. Maybe it's not worth worrying about.

Alan

I got the z-axis ballscrew mounted. I used a 3/4" piece of cast 6061 Mic-6 to replace the original carriage. I marked the top two holes with a transfer punch. The holes for the ballnut support I marked out using a small square to give me the top and bottom of the screw in relation to the carriage.

I made the ballnut support from a piece of 1" x 2" 6061 aluminum bar. It had a 3/8 hole through it that was on the edge of where the threaded hole would go. So rather than have an interrupted cut, I turned a plug and super glued it in place. That worked out fine.

After I laid out the bolt holes and drilled them, I marked the center of the screw on the carriage plate and the support piece. Then I used a transfer punch again to mark the holes on the carriage plate. I drilled them and tapped them. Next I bolted the support piece to the carriage. Then I used a transfer punch through the end bearings for the screw to mark the center for the hole for the ballnut. I bored the hole out to 0.875 and then threaded it 15/16" x 16 in the lathe.

I used a thin 1/2"x20 locknut to adjust the play between the two end bearings. I installed a 3/8" to 1/4" lovejoy connector and mounted the motor.

Now I need to wire everything up so I can give it a try.

Alan

I haven't hooked up the computer yet, but I hooked up a little manual controller I designed. The crossfeed (x-axis) is still using a 20tpi leadscrew coupled to the stepper with a 4:1 reduction. It is not exactly rapid but it is much faster than I could move it by hand. A single half-step would move the edge of the tool 0.000031 of an inch. It should get me enough accuracy for removing an appropriate amount of diameter.

The z-axis is direct-drive to a 5tpi ballscrew and it seems to be reasonably quick.

My manual controller seems to have some kind of wierd problem though. It has a dpdt (double pole double throw) switch to switch between the encoder feed and the pulse generator feed. It uses a 4p3t (4pole 3 position) switch to switch axis. this switch is fed by the output from the dpdt switch.

For the pulse generator feed it has a potentiometer to adjust the speed of the pulse and a spdt (single pole double throw) switch for direction. The adjustable feed works in both directions on both axis.

For the encoder feed it works fine on the X-axis (moves either direction) but for the z-axis it doesn't matter which way I turn the wheel, it always moves in the same direction.

Because the circuit works for the x-axis, I know that the pulses are being generated correctly from the encoder circuitry. So it seems that the problem must either be in the z-axis drive, the z-axis connections or the switching but I just can't seem to figure it out yet. Since the switching works for the pulse generator side of the circuitry, it seems unlikely that the problem is in the switches. I suppose that the z-axis drive could be enough different from the x-axis drive (they of both SS2000MD4 drives) to have a problem with the encoder circuit pulse width. Any ideas anyone?

By the way, the steppers are Pacific Scientific M22 on the leadscrew and P22 on the crossfeed.

Alan

Well, I still haven't figured out my problem with my MPG but I went ahead and hooked up my computer to the lathe. Just had a few minor problems at first. I had the x and z cables switched on the controller box. I put three connectors on the back of the controller, but I just have two drives in it, so I wired up to connectors 1 and 3 (x and z). But my z axis wouldn't run, so I hooked the manual controller back to verify that the controller was generating signals to the z-axis. Well, it was putting out signals to connector three but it was using the pins for the y-axis, so I just went into my ini file an switched the y and z pin assignments. Then it worked.

Then I ran some gcode cutting air. Everything works except zeroing the axii. So, now I need to add limit and home switches.

Alan

Good news, so make some swarf already!!

The home switch will be very utilitarian, but (IMHO) the limit switched will be a pain.

Anyway, great news....................ENJOY!!!!

Good news, so make some swarf already!!

The home switch will be very utilitarian, but (IMHO) the limit switched will be a pain.

Anyway, great news....................ENJOY!!!!

John,

I would love to make swarf, but how do I set the axii to zero without home switches?

Alan

If your not using Mach3 Lathe you should at least look into it. Their documentation will do a lot more for you than I can but I shall try.

Chuck a piece of stock and take a facing cut. Without moving the tool set (the long axis) Z zero.

Take one or two skimming turns on the radius of the piece (get a clean surface all the way round) and with out moving the tool set the X axis (cross slide) to what ever the material measures with a micrometer.

Take a programed practice cut and compare the actual O.D. to the programmed O.D.

Do they agree? If not, find out why. If they do, happy swarfing!!!

If your not using Mach3 Lathe you should at least look into it. Their documentation will do a lot more for you than I can but I shall try.

Chuck a piece of stock and take a facing cut. Without moving the tool set (the long axis) Z zero.

Take one or two skimming turns on the radius of the piece (get a clean surface all the way round) and with out moving the tool set the X axis (cross slide) to what ever the material measures with a micrometer.

Take a programed practice cut and compare the actual O.D. to the programmed O.D.

Do they agree? If not, find out why. If they do, happy swarfing!!!

Sorry, I don't do windows. I use emc2.

Alan

O.K. I just re-read my post and realized that I'm assuming that you are working in diametrical mode.
If you are working in radial mode you must divide your micrometer reading by two!!

Sorry, I don't do windows. I use emc2.

Alan


Who is that?

Who is that?

John,

EMC2 is open source controller software that runs under linux. It actually runs some commercial machines. I really like it, but I have to figure out how to zero the axii without home switches or mount some home switches.

It works great on my router but there I have limit and home switches.

Alan

http://www.machsupport.com/documentation/Using3Turn.pdf

Do yourself a favor, lay aside any bias you have about Microsoft and reconsider. My experience has shown me that Win XP is a stable reliable platform. It's the one that Mach uses. Mach offers a group of wizards for about anything you'd do on a lathe and you get the mill free.

I'd would be so lost without it I wouldn't have any interest at all in cnc without it. Below you will find two pages of wizards fot Mach Turn. Above is a url which will take you to their manual for turn.

Just a suggestion, life will be much better for you.

http://www.machsupport.com/documentation/Using3Turn.pdf

Do yourself a favor, lay aside any bias you have about Microsoft and reconsider. My experience has shown me that Win XP is a stable reliable platform. It's the one that Mach uses. Mach offers a group of wizards for about anything you'd do on a lathe and you get the mill free.

I'd would be so lost without it I wouldn't have any interest at all in cnc without it. Below you will find two pages of wizards fot Mach Turn. Above is a url which will take you to their manual for turn.

Just a suggestion, life will be much better for you.

John,

Even if I were willing to, I just can't afford it. Between linux and my Mac I am a happy camper. Don't want to start a flame war but I ain't switchin'.

By the way Mach is a derivative work based on emc.

Alan

You won't get any flames from me, just a dispassionate appraisal.

I earned my living for 15 years designing irrigation and fire alarm systems with Windows based computers.

I'm not a salmon, I don't need to swim up stream! Life is too short!

Enjoy!

You won't get any flames from me, just a dispassionate appraisal.

I earned my living for 15 years designing irrigation and fire alarm systems with Windows based computers.

I'm not a salmon, I don't need to swim up stream! Life is too short!

Enjoy!
John,

I used to program on pc's and unix boxes for a living. One day my company decided to see about porting our software to the Mac. I got a Mac to explore what that would take. I fell in love with the Mac and have used a Mac for all of my personal work for the last 20 years. Since the Mac now uses unix as the base for its operating system and since I had learned to program on unix, the use of linux for cnc was a natural.

I did teach in a public school system that used windows for a few years. I taught computer skills to kids using windows and helped support the teachers that were using windows also. Though a few of us used our own macs.

I actually do have one copy of windows on my Mac that I can use to run VCarve and NCPlot, I just don't run it very often. So, I do know something about windows, I just find it a pain in the butt and only use it when nothing else will do. I hated the problems that existed then and still exist with having to spend my time fighting viruses and malware. I strenuously object to Microsoft adding updates to my machine with no idea what they are for. When I installed XP on my Mac I used all the installs trying to get it to run and then had to call India to get another install authorized to finally get it to run. Everytime I run it the antivirus software tells me that it is out of date and I have to spend time updating it before I can accomplish anything. It is just too much wasted time for my taste.

As far as cnc goes, linux is a much better platform in my book. EMC2 has improved immensely in the last couple of years. In fact it has improved immensely in the last couple of months and the price is right.

Peace,
Alan

Well, I bought an E-machine from Costco for the purpose of running my equipment. There is no network out there and no anti-virus nor has there ever been an up date. I take programming to it on a thumb drive relative to the parts I'm cutting or when I update Mach3.
With Photo V carve, Sheetcam and Deskengrave I'm set for most anything I need to do. No mess, no fuss, no interference and no crashes. I wish I could demonstrate my system for you.

But then, I wouldn't want to intrude on a love (big grin) affair!

Well, I bought an E-machine from Costco for the purpose of running my equipment. There is no network out there and no anti-virus nor has there ever been an up date. I take programming to it on a thumb drive relative to the parts I'm cutting or when I update Mach3.
With Photo V carve, Sheetcam and Deskengrave I'm set for most anything I need to do. No mess, no fuss, no interference and no crashes. I wish I could demonstrate my system for you.

But then, I wouldn't want to intrude on a love (big grin) affair!

Thanks,
Alan

Well, I found out how to zero the x and z axii and I made my first cnc cuts on the lathe. The problem is that my camera battery went dead just as I started. I cut a radius on the end of my cam-lock lever for my tailstock. I will post a picture as soon as my camera battery is recharged. I should have changed the feed on the final cut to get a smoother cut, but live and learn.

Alan

Don't get too deep into those tailstock mods till you get a chance to see what I'm doing next! Here's some sketches.

John,

I already have mine done (third and fourth pictures). When I first did it, I just had a bevel or round-over on the end of the handle (first picture). So today I took the handle loose and turned a radius on it (second picture). Before I put it back in the camlock shaft, I polished the end a little on the buffer.

Alan

Awright! Good show!

I think the next step is to put on some kind of cover for the ballscrew.

John,

I have written some directions to myself on building the camlock modification. I got the basic idea from Steve Bedair's website. I think it is a lot simpler construction than your drawing. If you would like I would be happy to send what I have to you. I am going to put the directions up on my website but I haven't gotten around to it yet.

Alan

On the emc list I got the idea for an spindle encoder. The original implementation was done by Lawrence Glaister. It will use some of the optical switches that I built earlier. Two switches positioned so their signals are 90 degrees out of phase will provide the A and B quadrature signals and a third switch positioned slightly farther out will read the index hole. I used part of the gcode that he wrote but modified it for my purposes.

I cut the encoder wheel out of 1/8" tempered masonite. I will have to turn the edge slightly thinner on the lathe (I could have done it in the router when I made it, but it is easier to put it in the lathe than to try and recenter it and hold it down on the router.)

I am planning to mount it on the spindle where the drive gear currently is located. The drive gear is 12mm thick so I will make a mounting sleeve that will support the encoder wheel and with it occupy the same 12mm of space. I will also have to cut a keyway in it to go over the spindle key.

Alan

Not so sure about the masonite taking the RPM. I built a spindle disk from a cd. It turned into shrapnel scattered all over the shop. Ultimately a thin sheet of aluminum did the job. Be careful, my friend, protect those eyes!
jb

Not so sure about the masonite taking the RPM. I built a spindle disk from a cd. It turned into shrapnel scattered all over the shop. Ultimately a thin sheet of aluminum did the job. Be careful, my friend, protect those eyes!
jb

John,

It was a little bit thick for the opening in the optical sensor, so I chucked it with the 3-jaws through the center hole pressing out. I ran it at top speed on the spindle while I took about 0.010" off at a time for about the outer 1/2" and it seems fine. It tracks true and is actually a lot sturdier than a cdrom.

I think that the diameter may end up being to small though. I think I may have to make it about an inch or maybe 2 inches larger in diameter for the switch boards to be able to clear the pulleys. The larger the diameter the more likely the masonite is to have problems, so I may end up switching to a piece of aluminum. I have never machined aluminum on my router so, I may just machine it on the mill using my dividing head. Or maybe I'll be gutsy and try machining it on the router. I am a little worried about my router trying to cut aluminum at 20K rpm. It is not a variable speed. I am not sure what feeds (depth and speed) to use with a 1/16" carbide bit and I don't know if it will gum up.

Alan

A two flute bit and a lubricant (I use WD-40) will help with the alum.

I haven't yet been able to decipher exactly what your up on this little project.

Good luck, tho.....I'll be lookin over your shoulder!

Well I haven't finished the spindle encoder yet, so I can't thread on my cnc lathe. However, I have cut a couple parts with it and it works great.

One of the projects that I have in the works is a cnc conversion on my X2 mill. I will start a thread on it later. I took some of the ideas for the z-axis from Dan Kemp (Hoss26) and some from Ron Stirling.

I just couldn't resist trying to cut some of the parts on the cnc lathe. I cut the internal hole for the adjusting nut with a little cnc program and turned down the external diameter with another little program. I just faced it by typing in the gcode commands to the MDI interface (I think that I will add a facing routine to my software collection). I had to do the internal threading on my other lathe (can't wait till I get the spindle encoder done.). And I cut the tightening slots on my mill (no live tooling). The threads on the spindle are 1.156 x 32 and the nut was internally threaded to match that.

The first picture shows the part mounted in a 3" 4jaw on my lathe ready to run the facing operation. The second picture shows the finished nut on the rotary nut spindle. I still have to take it back apart and finish the corners on the base piece.

Alan

I previously posted this info in another thread. However, since I am now working on my conversion in earnest (I got my router running). I thought I would go ahead an start my on lathe thread.

Here are a few pictures of my variable speed conversion.

I used a Pacific Scientific DC motor that had a shaft the same size as the OEM Emerson motor (5/8"). This allows the use of the original pulleys and belts.

remainder deleted

Alan

Hello Alan:

I have a metal lathe and am trying to upgrade it to CNC and want to start at the main spindle motor and it sounds like you've already done some work in that direction already. It is a AC motor rated at the typical 1725RPM at 3/4 HP. What would be the ratings for a good typical servo motor (with encoder) to replace this? Servos are rated in oz./in. and I'd like to run this down to 200 RPM if possible.
Thanks for any help you can provide.

Bill

Hello Alan:

I have a metal lathe and am trying to upgrade it to CNC and want to start at the main spindle motor and it sounds like you've already done some work in that direction already. It is a AC motor rated at the typical 1725RPM at 3/4 HP. What would be the ratings for a good typical servo motor (with encoder) to replace this? Servos are rated in oz./in. and I'd like to run this down to 200 RPM if possible.
Thanks for any help you can provide.

Bill

Bill,

I used a 1 1/2 hp DC motor because I felt like the lathe was underpowered at low speeds anyway.

746 Watts equals one horsepower. Power (Watts) = RPM times in-oz / 1351. Figure out how many hp you need at what RPM. Then (HP * 746 Watts *1351)/RPM = in-oz torque. So (1.5 hp * 746 *1351)/3000rpm = 503 in-oz torque. I think. There are a lot of formulas posted at various places on the web. I got this from a document that Mariss Freimann wrote. I honestly don't know if I used it correctly though.

Alan

Bill,

I have seen a formula related to hp required for metal removal rates. That is how many horsepower it takes to remove so many cubic feet of metal per minute at a certain rpm but I don't know where to find it right now. Some of the other factors that come in to play are: what gearing do you intend to use? how deep of cuts do you want to make? and what kind of material are you going to be machining?

If you are running the servo at 200 rpm it will take a larger servo than if you are running the servo at 5000 rpm and gearing it down 25:1.

Alan

I want to stick with the stock gearing. My needs are not challenging. Mostly removal of aluminun and brass.

I have a motor attached to a 90 degree angle plate on the milling table (kind of like a poor's man's horizontal mill). By moving the milling table left or right I can mill longitudinal slots and grooves into the material held in the lathe spindle (after being machined to the proper diameter which is why it's on the lathe to start with). Currently if I want to mill four slots 90 degrees apart along the shaft I have to manually rotate the 3 jaw chuck 90 degrees, lock the spindle, make my cut, rotate another 90 degrees, make my cut, etc... I currently use a makeshift indicator aligned to marks printed on the jaw chuck. This is a manual process prone to cumulative errors.

Why not take the material out of the lathe and attach it to the table and mill slots using the vertical mill, you might ask? The problem is that I make round tapered and square tapered shafts and trying to hold tapered items in a vise is impractical. Also, as long as I don't move the tailstock taper, the depth of all slots and grooves will be consistent.

I would like to use cnc to rotate the main spindle 90 degrees, have some decent holding torque, have the cnc move the x and y axis to make the cut (x axis cutting the length of the spindle, y axis cutting the depth). Have the g code turn the spindle 90 degrees, repeat until all slots are cut. The depth of cuts are very shallow, less that .125" and multiple passes are allowable so the holding torque doesn't have to be tremendous.

Then when a new part is loaded in, I use the serve to rotate the stock at 600rpm, use a bit in the tool post to reduce the diameter, then command the servo to stop at the 0, 90, 180, 270 positions while the horizontal mill cuts the slots. The main spindle servo would be used for two different functions.

This is why I was so interested in your modification of the lathe spindle motor. I need a cnc controlled spindle motor which can command the 3 jaw chuck to rotate through a prescribed number of degrees and hold with some reasonable torque.

Does it seem like your 1 1/2hp DC motor with an encoder will do the trick in a cnc system?

Thanks for any suggestions and sorry for writing a book.

Bill

I want to stick with the stock gearing. My needs are not challenging. Mostly removal of aluminun and brass.

I have a motor attached to a 90 degree angle plate on the milling table (kind of like a poor's man's horizontal mill). By moving the milling table left or right I can mill longitudinal slots and grooves into the material held in the lathe spindle (after being machined to the proper diameter which is why it's on the lathe to start with). Currently if I want to mill four slots 90 degrees apart along the shaft I have to manually rotate the 3 jaw chuck 90 degrees, lock the spindle, make my cut, rotate another 90 degrees, make my cut, etc... I currently use a makeshift indicator aligned to marks printed on the jaw chuck. This is a manual process prone to cumulative errors.

Why not take the material out of the lathe and attach it to the table and mill slots using the vertical mill, you might ask? The problem is that I make round tapered and square tapered shafts and trying to hold tapered items in a vise is impractical. Also, as long as I don't move the tailstock taper, the depth of all slots and grooves will be consistent.

I would like to use cnc to rotate the main spindle 90 degrees, have some decent holding torque, have the cnc move the x and y axis to make the cut (x axis cutting the length of the spindle, y axis cutting the depth). Have the g code turn the spindle 90 degrees, repeat until all slots are cut. The depth of cuts are very shallow, less that .125" and multiple passes are allowable so the holding torque doesn't have to be tremendous.

Then when a new part is loaded in, I use the serve to rotate the stock at 600rpm, use a bit in the tool post to reduce the diameter, then command the servo to stop at the 0, 90, 180, 270 positions while the horizontal mill cuts the slots. The main spindle servo would be used for two different functions.

This is why I was so interested in your modification of the lathe spindle motor. I need a cnc controlled spindle motor which can command the 3 jaw chuck to rotate through a prescribed number of degrees and hold with some reasonable torque.

Does it seem like your 1 1/2hp DC motor with an encoder will do the trick in a cnc system?

Thanks for any suggestions and sorry for writing a book.

Bill

I am not trying to convert my DC motor to a servo. I am working on an encoder that will mount on the spindle, not on the motor. However, I am thinking about adding spindle speed support (considerably different from full servo support). I am not sure that the motor and the stock drive train would have enough hold for what you are wanting to do. Even if the motor has enough power, I don't think the stock drive train could hold accurately as a "4th axis".

You said it isn't a very challenging thing that you are trying to do, but powering a spindle to turn is significantly different from powering a spindle to hold position against the forces of milling an item held in the spindle. I really question trying to hold position like a 4th axis with a simple belt drive.

You might want to think about a mill with a geared 4th axis. If you can hold the part in a lathe chuck, then you could hold the part on a mill in a lathe chuck mounted to a stepper motor driven rotary table.

Alan

Well I ran into a problem earlier with my spindle encoder effort. My optical switch was too big to mount between the back of the headstock and the spindle pulley.. So, I re-did my optical switch pcb to shrink it a little bit. I redesigned it to use surface mount technology. Then I got sick for a couple of weeks

Finally, back at it today. Wow, are those parts small. When I was putting some boards together today, I lost one of the resistors. I looked all over for it. Finally, found it stuck to the palm of my hand.

I have to wear a magnifying visor to see what I am doing. I built 5 of them in about an hour this afternoon. The first one I messed up and when I tried to fix it, I spoiled the pcb. The next four when together fine and all worked.

Now I have to figure out the mounting and wiring.

Alan

i have a question about your sensor? i'm basically running an optical switch to give me a feed back pulse as a spindle timer for threading. when i look at mach 3 with the spindle off i'm reading about 200 RPM and its fluctuating. i am wondering what you guys are seeing on mach 3 when the spindle is off? also any ideas on how to correct this would be great.

thanks
Jerry

You are probably picking up an errant signal.
Try moving your cable about in it's routing from spindle to connection. Maybe shielding for BOB/driver/power supply/A.C. inlet?

Great job. Your going to love spindle synced motion once you get your encoder straitened out. You should be be able to rigid tap (if you can control your spindle reversal from emc2 - and mount the tap in the tool post.) - or put a stepper on your tailstock ;) You will be able to do some really funky stuff - Emc2 will blend multiple spindle synced motions together. You should be able to do things like fusee / variable pitches and such.

http://axis.unpythonic.net/01181704483

(glad you like emc2) :)

Your friendly neighborhood emc2 advocate.

i have a question about your sensor? i'm basically running an optical switch to give me a feed back pulse as a spindle timer for threading. when i look at mach 3 with the spindle off i'm reading about 200 RPM and its fluctuating. i am wondering what you guys are seeing on mach 3 when the spindle is off? also any ideas on how to correct this would be great.

thanks
Jerry

Jerry,

I can't help on Mach, because I am running EMC2. I am actually building a quadrature encoder that will have a, b and index channels.

Alan

Well,

I lost two weeks to illness, a week recovering and then I spent two weeks in Mexico. So I guess it is time to get back to work.

I had both axis (X and Z) set to 3.5 amps. One of the steppers was fine (a PacSci P22 on the X axis) but the other one (a PacSci M22 on the Z) was getting too hot, so I put another P22 on the Z axis now everything runs plenty cool. It is kind of funny the M22 is rated to be more powerful but it takes less current to drive it to its rated power. The P22 is rated for max of about 35 volts while the M22 is rated for 65 volts.

My X axis tops out at 7.5ipm because I have 4:1 gear reduction driving a 20tpi screw and driver only half steps and it won't put out steps to move it faster without producing too much resonance. I may buy one of the new Gecko G540's when they are available.

Right now a half step (supposedly) moves the tool 0.000031". So a full step would be 0.000062". Now if only my leadscrews were that accurate.

I plan to ultimately replace the 20tpi leadscrew with a 5tpi ballscrew, but I am still not satisfied with any design that I have come up with. That would theoretically give me 0.00025" per full step. It should at least allow me to achieve diameter accuracy in the order of 0.001" maybe a little better.

Last night I started working on the encoder again, I hope to get it finished in the next few days. I sure like the finish that I now get in facing off.

Alan

Alan,

i have completed the mechanicals on my 9x20 as well. running the xylotex kit with a 10 tpi lead screw on the x axis and a 5 tpi ball screw on the z axis, i am getting rapids at 85 ipm on x and 105 ipm on z. i am using 425 in/oz motors and i have a 30 tooth pulley on my motor and 15 tooth pulley on the screw, which effectively cuts down my threads per inch to 5 tpi for the x and 2.5 tpi for the z.

Runner4404spd,

My Z is direct drive so it is 5tpi but my X is geared 4:1 reduction so it is effectively 80tpi. The biggest problem is that my drives are Superior Electric SS2000MD4 which have full or half-step modes but nothing to combat resonance. I can only get the steppers to turn a max of 600 rpm (even unloaded on the bench). I can get 120ipm out of my Z but only 7.5ipm out of my X. I suppose that I could build a damper like SJH to deal with the resonance issue. However, since I plan to eventually replace the X leadscrew with a ballscrew I want to focus on that (once I get the encoder working).

Alan

I just turned (what was supposed to be) the spindle encoder mount. It came out exactly as I had spec'd (within a few tenths). The problem is that in being out of commission for a month I forgot that I had changed the design and hadn't updated the gcode. Oh well, at least I know that it will turn to specs.

Alan

I have a 3 in 1 machine and am planning to get the camtronics 3 axes stepper system- would your board adapt to it to allow electronic control of the manual feeds?

I have a 3 in 1 machine and am planning to get the camtronics 3 axes stepper system- would your board adapt to it to allow electronic control of the manual feeds?

Are you talking about my manual controller board? If so, then yes. I actually have a 4 pole 3 position rotary switch in my box already. So it will work with a three axis system. I have it set up with a db25 connector with the same pinout as the parallel port on my computer so that if I want to use it, I just unplug the cable from the computer and plug it into the manual controller box.

I bought a 2P pci card for my computer so that I could use it as an MPG to emc2 but I haven't gone there yet.

I have also toyed with the idea of putting two boards in a box so that for my lathe I could have mpg wheels for both axis alive at the same time.

Alan

I am almost done with the spindle encoder hub. I just have to cut the keyway for the spindle key. Here are a couple of pictures as I was machining it. CNC sure makes for faster machining. I faced both sides, then bored the internal hole, then faced it down to fit the encoder wheel all under cnc control. The only manual operations were flipping over in the chuck and drilling the pilot hole.

Then I mounted it in the chuck of my indexing head on my mill to drill the holes for the 4x40 screws to mount the encoder wheel.

Next steps are to cut the keyway, mount it on the spindle and then mount the optical switches and align them.

Alan

I originally intended to mount the encoder wheel as close to the headstock as possible. However, when I mounted it on the spindle, things did not seem to want to go back together smoothly. When I got the spindle nut on I discovered why. The wheel was running into a socket head capscrew protruding from the headstock. The result is a messed up encoder wheel. I got the wheel sort of straightened out but I am going to have to build a new wheel before I mount the detectors (it has too much runout to use as is). I went ahead and turned it around and mounted it on the spindle. It clears everything fine when mounted this way. Now to build another encoder wheel.

Alan

Well I haven't made much progress I have been having too much fun. However, all good things seem to come to an end.

I completely wore out the crossfeed nut. I had made it out of brass and the leadscrew that I turned out of 12L14 steel was too rough and it just ate it up. I had a spare nut that I had made first (it has more backlash than I wish). I put it in and got working again. But I polished the leadscrew first!

I can't afford to buy a smaller ballscrew just now, and I haven't been able to design any setup for the 5/8x5tpi ballscrew that makes me happy, so, I am now making up a new leadscrew (1/2"x10tpi Acme) and a nut out of delrin. If this works reasonably well, then I am thinking about making another nut out of brass or bronze and lining it with something like Moglice (provides much less friction than normal metal on metal screw and nut combo and if done correctly almost zero backlash).

Alan

I got the crossfeed screw and delrin nut made and installed.

The screw binds up about 1/4" from the extreme end of travel. So I will have to figure that out.

It is 10tpi instead of the previous 20tpi so it travels twice as fast. I had to cut the number of steps per inch in half to account for the change in pitch. I also forgot for a couple of minutes that the original screw was left hand thread while the new one is right hand thread. When I went to jog it was going the opposite direction but putting a minus sign in front of the scale value fixed that.

My crossfeed screw is geared down 4:1 and I am running half step on my stepper drivers, so, 4x10x400=16000 steps per inch or 0.000068" per step. That makes cutting close to what you want in diameter work fairly well.

Next I have to get the spindle encoder installed.

Alan

I machined a plate to mount the optical switches on and mounted it on the lathe.

I used my CNC router to cut the plate. I tapped the holes for some nylon PCB standoffs, installed the standoffs on the plate and then mounted the three boards. I drilled two holes in the lathe shield for screws to fasten the plate to the lathe. The plate has adjustment slots to allow its position to be shifted slightly so that the holes on the encoder wheel line up with the optical switches.

I have a DRO-350 that I made for the lathe but have never installed. I used it to test out each of the individual boards. The lowest board is positioned on the outer index ring and the top to boards are positioned on the inner 100 count ring. I was really surprised to see that the DRO speed indicator read 100 times faster on that ring than the index ring. I thought the 100 cnt ring would probably be too fast for the DRO to read.

My battery ran down on my camera so I will post a picture of the DRO reading the RPM later.

Next I have to wire it up, make the appropriate changes in my HAL file and try it out.

Initially I am going to try and get it running as an encoder with channel A and channel Z (index). Then I will try to get the channel B to work but that will probably entail moving my oscilloscope out into the shop to tune channel B to 90 degrees off of channel A.

Alan

Here is a picture of starting the wiring for the encoder and a picture of the DRO-350 reading 525 rpm from the encoder index. The flash almost washed out the display.

I have the spindle geared down considerably. 525 rpm is the top speed in this range and I guess the motor is running about 4000 rpm. The DRO will read out rpm down to about 20-25 rpm before it drops out.

I wired the connector block the same as a US Digital A,B,Z encoder.
Pin1 -- GND
Pin2 -- INDEX
Pin3 -- CHANNEL A
Pin4 -- VCC
Pin5 -- CHANNEL B

Each board has a NO and a NC connection. I may have to use the opposite connection to get the Channel B to work.

Alan

OK, I got I thought I had it all wired up correctly. Wrong. I am getting no signal on the parallel port input pins to the computer.

I am using a CandCNC mini-IO BOB. I picked up +5v and PCGnd from the BOB for the optical switches and fed the outputs from the optical switches to the opto-isolated inputs. As the spindle turns I can see the indicator leds on the switches changing states, so it appears to be working.

Does anyone see the problem?

Well I haven't solved it yet but it appears to me that I have no connection to the isolated gnd for the opto-isolators. No return path, so the signals don't get through.

My guess is that I am going to have to use something like a 5v wall wart to power the optical switches and connect the optical switches gnd to the wall wart gnd and to the isolated gnd on the BOB.

Does this make any sense?

Alan

Well, I tried the wall wart and that didn't help at all. I guess that I am going to have to try and tap into the power to the BOB's opto isolator. What fun.

Alan

Well, no joy in Mudville. I found out that I need to invert the signal from the optoswitches with NPN transistors instead of the PNP that I am using. My breakout board's optoisolators use pullup resistors and my PNP transistors use pulldown resistors (in short they don't like each other).

So I designed a small inverter board. It will have 3 NPN transistors and three bias resistors for the input from my optoswitch. It will have inputs for the three opto boards (signal, power and ground) and also have the same output pinout as a standard encoder.

I laid out a small circuit board (0.5" x 1.4") and tried cutting it out with my CNC Router. I used a 1/32" endmill for the drilling and milling. It worked OK for the drilling but it is too large cutting between the traces so I ended up with some whiskers shorting adjacent traces where it couldn't get through. So, I ordered some 0.010" carbide 50° engraving bits for milling the trace outlines.

Alan

All this is going over my head at about the same altitude as the space station. What is the object of this exercise?

I thought your rig was doing a great job as it was....if it aint broke..........

Sorry just a bit dense in my elder years!

jb

John,

Working on getting it to cut threads. That requires the ability to sync the spindle to the Z-axis travel.

Alan

Alan,

I cnc'ed two lathes a couple of years back and added a simple spindle sync circuit and gave pretty good detail of how I did it. I'll see if I can find the post and add a comment to bring them to the current threads. They will at least show you how I was able to automate threading using a proximity switch from automation direct.

Ron

Here is a simple and inexpensive index pulse option. Use one of these http://www.lynxmotion.com/Product.aspx?productID=58&CategoryID=8
mounted close to the spindle and have a part of the spindle covered with a light colored material (I used paper labels on mine). The calculations for the size of the flag didn't work for me, so I just kept increasing the size of the flag until I got a stable pulse.

Here is another solution for the index pulse http://www.cnc4pc.com/Store/osc/product_info.php?cPath=25&products_id=129
Mine actualy has the older version of this board with an optical switch rather than the one they use now.

Alan,
I did find my previous threads concerning automated threading and spindle sync pulses.
One in on the 9X20 Harbor freight and the other is the "Lathemaster 9 X 30 CNC adventure" if you look at post #40, #41 (PDF attachment file), and post #47, you can see How I did it. I threaded many times using this set up.

I will be out of town for the next couple of weeks (so if you have questions, it will be a while before I can get back to you)

Good Luke,

Ron

Ron,
your attachments aren't showing up!

Thanks, guys, but I am not doing a single line detector. I am building a 100 line plus index encoder. When run in quadrature mode this will give 400cpr plus index. EMC2 can now support a single line sync signal, but, since I started out to use the multi-line encoder I want to finish it.

My encoder wheel and detectors are already mounted on the lathe and working.

The problem that I ran into is that my BOB uses 470 ohm pull-ups on the opto-isolator input and my detectors are using a 560 ohm pull-down circuit. This results in the the detector signal being held higher than the logic 0 voltage all the time. Thus the parallel port pins are never seeing a low going input signal.

My solution is my small converter/inverter board which will work with the BOB's pull-ups and will be driven by the PNP outputs of my Detector boards through a 10K resistor to the base of an NPN transistor. The emitter of the NPN transistor is hooked to ground and the collector will connect to the opto-isolator input/470 ohm pull-up.

I have already redesigned my detector boards to use NPN transistors instead of the PNP transistors that they now use but I don't want to go to the expense of having a bunch made until I verify the operation with my small converter board.

Alan

OK, my persistence paid off.

My converter/inverter board solved the problem. As soon as I hooked it up I could see the signals on the computer. Then it was just a case of telling EMC2 which pins were which signals. Even the little speed bar in my pyvcp panel works.

Now I just have to learn how to use the threading codes to cut threads.

Alan

Here is a video of my lathe cutting one of a set of parts for my CNC router.

YouTube - CNC-BearingStandoff2ndOp

I wrote a gcode routine to perform the same first op on 8 consecutive pieces. It faces off the end, cleans up the entire piece, cuts the bearing boss and then parts off the part and pauses for the shaft to be shoved in to the tool to cut the next part.

The second op starts with the first piece in the chuck, it faces it off to length, cuts the shoulder and then pauses for the next part to be inserted.

These parts will be the bearing standoffs for the y-axis bearings on my revamped router.

Alan

I hooked up my Logitech Attack 3 joystick to my lathe controller. I have the jog working but I haven't configured most of the buttons yet. It has 11 or 12 buttons besides the joystick.

EMC2 has a all of the necessaries for hooking up a joystick to a mill. It is basically only setup to handle the X and Y axis. So, when I hooked it up to my lathe I changed so that the z-axis moves when the handle is moved side to side and the x-axis moves when you move the handle forward and backward. Basically standing in front of the lathe like in manual operation, the axii move in the direction that you move the handle. Then I set up the trigger for finefeed, thumb1 for slightly faster feed and thumb2 for rapid jog.

I will probably set up a button (or two) to act as a slider for spindle speed (once I get the spindle speed control setup). I wonder if I could figure out how to use the scroll wheel to control spindle speed?

Another button will probably be setup to control a mister-coolant system.

I am a little reluctant to setup a button for the spindle on off. I don't want to bump a button and have the spindle turn on or off unexpectedly. Maybe if I build a more complete console then that might be a reasonable thing to do. Then I could also include a "machine-on" button as well and maybe a couple of buttons for home-x and home-z. Program "run", "pause", "resume" and "stop" would also be a useful buttons.

I guess I will have to sit down and map the various options to see what I have enough buttons to do and what is safe to do.

Alan

Alan,

Are you using steppers and parallel port with EMC2 or servo's and third party hardware (e.g. pci PICO systems, etc.)?

Just curious about your hal files and interfacing the joystick.

A few of us may be further amused if you post a video of your joystick jogging and thumb trigger operation.

Nice work.

Alan,

Are you using steppers and parallel port with EMC2 or servo's and third party hardware (e.g. pci PICO systems, etc.)?

Just curious about your hal files and interfacing the joystick.

A few of us may be further amused if you post a video of your joystick jogging and thumb trigger operation.

Nice work.

I am currently using steppers and parallel port. I have several servos but I don't have any servo drivers.

I just basically followed the directions in the wiki here (http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Simple_Remote_Pendant). Then changed these lines in my custom_postgui.hal file:

net joy-x-jog halui.jog.0.analog <= input.0.abs-x-position
net joy-y-jog halui.jog.1.analog <= input.0.abs-y-position
net joy-z-jog halui.jog.2.analog <= input.0.abs-z-position to this:

net joy-x-jog halui.jog.0.analog <= input.0.abs-y-position
net joy-y-jog halui.jog.1.analog <= input.0.abs-z-position
net joy-z-jog halui.jog.2.analog <= input.0.abs-x-positionThen I set the speeds to be 0.5, 5, and 50. Increasing by a factor of ten.

I will try to get a short video in the next few days. It is a little hard to take a video holding the camera in one hand, keeping it focused and use the other hand to jog the lathe. I'm not all that coordinated.

Alan

I just took a look through your build log and I was admiring your very pro looking circuit boards.

Where did you get them done?

Very nice work all round by the way.

Dan

I just took a look through your build log and I was admiring your very pro looking circuit boards.

Where did you get them done?

Very nice work all round by the way.

Dan

Dan,

I did all the schematics in Eagle. Until version 5.2 of Eagle, I had been using Osmond-Quartz on my Mac to actually lay out the PCBs. All of my circuit boards up to the little inverter/converter board I had made through BatchPCB.com. The last PCB (my Inverter/Converter) I used Eagle and PCB-GCode to create the gcode and then I milled it on my CNC Router.

BatchPCB charges about $2.50 per square inch for boards, too high for production but pretty good for prototyping. Turn around time is probably too long for anyone doing commercial development but I think it works if you are patient.

Thanks,
Alan

Well, a delrin nut may be fine for a router but it really wasn't working well for my lathe. I just couldn't hold much better than a couple thousandths. I would get it set right on the money and then at the final diameter trying to do a finish cut I would find it off by 1, 2 or even 3 thousandths. I think the nut was just flexing too much for reliable cutting of precise diameters.

So I made a new nut out of cast iron. I got it done and it is installed but I haven't done any testing yet. It feels like it has no backlash. I was thinking about cutting it oversize and fitting it close with moglice, but I think that I will try it like it is for now.

The switch to a 10tpi screw doubled my max velocity from 7.5 to 15ipm on the X axis. With 4:1 gearing, 200 step motors and 10 tpi, I have 8000 full steps per inch ( I am running halfstep so it is really 16000 steps per inch). So, I have 0.000125" per full step. Hopefully this will prove more accurate than with the Delrin nut.

It is really wierd how these machines are a mix of metric and imperial measurements. The mounting screw is 6mm but the boss has to fit a hole bored in the crossfeed that is 0.375". Why not 10mm (0.3937")?

The first picture shows the partially completed delrin nut (now replaced). The second picture is the partially completed cast iron nut. The third picture is after the mounting hole has been tapped 6mmX1.

I forgot to take a picture of the threading operation. I drilled a 0.375 hole lengthwise through the nut and then I used the G76 gcode to tap a 10 tpi starter thread out to about 0.450. Then I made a tap out of a length of the acme threaded rod and used it to tap the nut to final diameter.

Alan

Someone asked me to post a drawing for my z-axis motor mount. Since my mount bolts to the existing holes for the leadscrew end bushing block, you would need to verify those measurements on your lathe before using. These lathes do not seem to be produced with highly repeatable measurements for all parts. Some parts are fairly uniform but others seem to have been produced with hand tools.

The first pdf is for the bearing block and the second is for the stepper motor mount. The length of the standoffs that you use depends on the coupling that you use.

Alan

Very noce Job. I love the workmanship

Very noce Job. I love the workmanship

Thanks for the compliment,

Alan