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IndustryArena Forum > MetalWorking Machines > Benchtop Machines > PM1022 lathe CNC Conversion
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  1. #41
    Join Date
    Dec 2005
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    91

    Re: PM1022 lathe CNC Conversion

    The drill is a "RAM 1/2 *** Reversible Drill" made my "******* Tool Company" from "C***** ILL". "Made is USA". The label is a little scratched up and hard to read.

    I inherited this from my father. He bought it in the mid 60s so only about 55 years old. The reverse quit working but forward (more important) still works fine. Not variable speed. I have little use for a 1/2 drill so this one serves me well. It is vintage.

    Thanks.

  2. #42

    Re: PM1022 lathe CNC Conversion

    Mine isn't variable speed either. Just on or off. Quite the wrist breaker if you aren't ready for it.

    Rarely do I need a 1/2" either, and I also inherited mine from my father. I think he stole his from the Air Force when he left.

  3. #43
    Join Date
    Dec 2005
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    91

    Re: PM1022 lathe CNC Conversion

    Sounds like a nice retirement gift to me. :-)

    Thanks.

  4. #44

    Re: PM1022 lathe CNC Conversion

    I'm fairly certain he felt the same way.

  5. #45
    Join Date
    Dec 2005
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    91

    Re: PM1022 lathe CNC Conversion

    It’s been some time since I reported in. I’ve been busy though and have made some progress.

    We moved to our winter digs outside Quartzsite AZ in November. The lathe and PM728 bench mill came with us as it’s where they are destined to live. I received a CNC kit from Precision Matthews for my PM728 and got the CNCed mill going in January. There is still work to do but it’s functional. So back to work on the PM1022 lathe.

    Most of the major parts are completed as seen below.

    Attachment 461252

    I haven’t started installing the parts on the lathe as I’m using it to build parts. I hope to have everything ready before starting the installation and minimize the number of assembly/dis-assembly loops. You know, avoid get half way though the install and find the manual lathe is needed, another loop.

    The overall design is described in previous posts. I haven’t deviated from the design yet, but may have to once I start the installation.

    Let’s take a look at the parts made so far.

  6. #46
    Join Date
    Dec 2005
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    91

    Re: PM1022 lathe CNC Conversion

    The ball screw is fixed axially at the tailstock end. The design calls for open angular contact ball bearings with seals at the end of the bearing stack. This is the same scheme used in the X axis above.

    Attachment 461254

    The small spacer rings are shown, but the larger are awaiting material. The mounting holes in the bearing block and spacer will be done at time of alignment and assembly.

    I’ve had trouble with the bearing block. The bearing recess was first cut on the lathe, no problem. I cut the outside from both sides on the PM728 mill with 3/8” end mills. I don’t think I could use 1/2” full width cuts in steel on the PM728, and the 3/8 end mills aren’t long enough for full depth. That left a pretty good “parting line”. There’s also, at least one, machining error as can be seen below. The flat on top was anticipated. The stock was 2” while the part was originally a little over this. (bad design) So, I accepted the flat rather than starting with 2.25 or 2.5” stock.

    Attachment 461256

    I cleaned it up with a belt sander and it came out OK.

    Attachment 461258

    Attachment 461260

    But the real trouble came when I started making a bearing replacement plug for eventual alignment. I found the bearing bore to be some 0.004” out of round. It was sure nice when I took it off the lathe. I’m thinking the residual stresses in the cold rolled stock tweaked it when the outside was cut. That’s a real bummer. I tried to bore out the bearing seat on the mill. Something was off and the boring bar hit the bottom of the bore hard. Foolishly I retracted the boring head really messing up the bore, as seen in the above picture. I plan to stress relieve the a new piece of stock and try chain drilling the outside. We’ll see.

    But something wasn’t right. I started checking the mill and found the Z axis was misbehaving. Further investigation found the Z axis link between the ball screw nut and the head (spindle/motor/etc) was failing. The screw holding this part to the head pulled out as I was snugging it. So this part will need a remake. Precision Matthews will replace it, but it is coming from Taiwan. It will be a lot quicker to make one. However, that’s an entirely different story.

    The large round part is to hold the big end of a telescoping spring, ball screw cover. The design calls for a 2 3/8 OD x .065 wall tubing. Sounds standard but when it came time to order some I couldn’t find it listed anywhere. So I obtained some thicker 2 3/8 OD tubing, welded on the end cap, then bored out to 0.065” wall. For this part it went well until I took a last pass to clean up the bottom of the bore. Somehow I slipped 0.10” in depth giving a bottom dimension of 0.025” rather than 0.125”. I decided to try saving the part rather than start over. I cut out the bottom and welded in a new one. Came out OK and will work.

    Attachment 461264

    Finally, when assembled it’ll look something like this.

    Click image for larger version. 

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    Progress but still work to do on the tailstock support.

  7. #47
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    Dec 2005
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    91

    Re: PM1022 lathe CNC Conversion

    The new apron mounts to the underside of the carriage using the same holes as the original apron. It’s done but for the end bores (and mounting holes) which will be done after assembly and alignment. The parts look like this.

    Attachment 461268

    Click image for larger version. 

Name:	Apron-2.jpg 
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ID:	461270

    The large cut out on the front gives room for the X stepper motor. The cap on the right side bolts on top of the ball nut and holds the right side telescoping spring. The cup on the left inserts into the apron and holds the large end of the left telescoping spring. I chamfered the outside edges I thought would be touched. The C-bores for the screws leave little room for the chamfer so I skipped around them as can be seen.

    I’m pleased with the way this is coming out, if it fits. It’s now ready to be mounted to the lathe and aligned. The bores on the sides need to be done after alignment is determined.

  8. #48
    Join Date
    Dec 2005
    Posts
    91

    Re: PM1022 lathe CNC Conversion

    The box at the headstock will bolt to the lathe bed using the same mounting holes as the gear box now does. The box is a four sided aluminum structure open the the bottom and the left. It houses the Z stepper motor, non-fixed ball screw bearing, and timing belt drive connecting them.

    Attachment 461272

    The cut out on the front of the box is for a cooling fan. The bearing support on the right will be mounted into the box once alignment is established. The mount has a small tube to support that end of the telescoping spring. I had a nice piece of 12L14 steel for this. Since it’s not weldable I used loctite to hold the small tube in place. The ball screw end will be machined on assembly, after its actual length is known.

    The stepper motor is mounted to the aluminum piece shown. Once on the motor the timing belt pulley is put in place, timing belt wrapped, then the assembly is screwed to the slots on the right side. The slots give adjustment for belt tension. The motor mount was the only tricky part here. I started this on the lathe. After facing the block a 1/2” hole was reamed through to locate center from each side. In this first four jaw set-up the recess for the stepper motor was machined. The part was flipped, centered and bored for the pulley recess, second set-up.

    The third set-up used the scrap cut out from the apron front as a jig. It was squared up and holes drilled and C-bored for cap screws from the bottom. From the top a boss to match the stepper motor recess was machined. The motor mount was screwed to this sacrificial block held in a vice. The motor mount was squared in place and the screws tightened from below.

    Attachment 461274

    Attachment 461276

    Then in this third set-up the outside and side cut-outs were machined using a 1/2” end mill.

    Attachment 461278

    Attachment 461280

    The side cut-outs went lower than anticipated, as least further than I think reasonable. You can see this in the last picture. It won’t effect the function of the part but I wasn’t pleased. It’ll work fine so I don’t plan to remake the part. I think this is a result of the Z axis problem.

    I believe the headstock box is ready to be mounted and aligned. As with the other sections, mounting holes and bores will be done during assembly.

    So assembly is very close. However, it’s getting too hot to be in Quartzsite and it’s time to go traveling for the summer. I’ll be away from the lathe until fall. The mill also needs repair before I can continue, which I hope I can get done in the next week or two. Stay tuned. I should have Internet so if you have questions or advise please add comments.

    Thank you.

  9. #49
    Join Date
    Dec 2005
    Posts
    91

    Re: PM1022 lathe CNC Conversion

    This summer I made another go at machining the tail stock bearing block. If you remember, I had trouble with the first one due to residual stresses in the cold rolled stock. I cut the bearing recess first, when it was easy to hold in a four jaw chuck. The size was just right until I cut the outer profile. Then it went out of round. It had other problems also but this was the main one affecting function. So I tried again.

    I started with a block of the same 1018 cold rolled stock. However, this time I put it though an annealing cycle in the furnace. This should have solved the problem but I didn’t want to make a third one. So, I left a good margin in the bearing bore then cut the outer contour. Finally I made a fixture to hold the awkward thing in the lathe for final boring. More work but less chance or warping.

    I’ve been trying to learn Fusion 360. So rather than putting the part on its side and milling the contour I put it upright and used 3D machining for the profile. I tested the program on wood before committing to steel. In doing this I found my converted knee mill would drift, lose steps, on this long program. After a week or so I isolated the problem points in the G-code so I could at least test with a shortened program. I’d recently moved from using the parallel port to a MESA card with LinuxCNC. Back in the configuration I found the machine needed a slower acceleration. That seems to fixed the problem and I’m back up and running.

    With trepidation I put the steel blank in the vice and hit go. I used a 1/2" carbide 4 flute roughing mill and a 1/2" carbide 2 flute ball end mill. The roughing pass gave a stair stepped profile.



    The finish pass went end to end following the profile.



    I should have used a water line finishing tool path. The tool path I used brought the ball end mill down into the fillet rather than cutting with it. It worked OK but the machine was not happy with that small plunge. The part coming off the machine looked like this.



    A few minutes with the belt sander and a finished part popped out. Well, at least a part with a finished profile. I then went to the lathe and bored the bearing pocket.


    finished.jpg

    I’ll drill the mounting holes when I figure out the process to put it on the lathe. But for now I’m happy with the new part.

    Thanks.

  10. #50
    Join Date
    Dec 2005
    Posts
    91

    Re: PM1022 lathe CNC Conversion

    I recently found we’re going to be in our summer digs, Prescott, for another month or so. I really wanted to get some work done on the lathe conversion. So, I took the utility trailer to Quartzsite and brought the little guy back. This is good for the conversion work as I have a larger shop in Prescott. It’s hard to convert a machine when you’re depending on that machine to make parts. This leads to lots of taking apart and putting together. Here I have a nice lathe to build parts for the PM1022.

    I started by mounting the new apron. It was pretty straight forward but I took my time so as to not mess up any nearly completed parts. Right off I found the cutouts on the back side were too small. I don’t know where I went wrong measuring but I had to increase these for clearance with the saddle and main casting. See the Dykem on the apron.

    Once it fit into place I clamped it and used transfer punches to mark the holes. Over to the mill to drill and tap threads.

    Attachment 470942

    Then reinstall and mark the location of the taper pins. I used a drill through the taper hole just large enough to clear, just far enough to mark the spots. Then on the mill I used these spots to drill 3 /4” deep holes the size of the taper small end. I didn’t center drill as I waned the drill to center on the existing spot. Finally used a tapered reamer by hand to taper the holes and align them with the taper in the saddle casting. It fits together well.

    Attachment 470944

    With the taper pins the apron can be removed and reinstalled without worrying about alignment.

    The holes for the Z ball screw and nut mounting still have to be put in. However, these need to align with the tail stock bearing. I have a plan for this alignment but it’ll have to wait for the bearing block mounting.

  11. #51
    Join Date
    Dec 2005
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    91

    Re: PM1022 lathe CNC Conversion

    I think I’ve figured out how to mount the tail stock bearing block. It follows very closely the original design.

    Attachment 470956

    I spent quite a bit of time figuring out how to match taper holes in the spacer block with the existing holes in the casting. The closest thing I could figure was to put pointy taper pins in the casting to mark the Dykemed spacer block. Didn't seem overly accurate. Also considered tapping the block into pointed taper pins and using the center punch marks for drilling. I was worried I couldn't remove the taper pin afterwords though.

    I finally decided to put new 3/16” reamed holes in the casting to match holes in the spacer block. I placed these between the threaded hole and the taper pin hole. You can see these right next to the counter sunk holes in the picture above. The spacer block is shown in position below.

    Attachment 470958

    Once it is aligned I'll drill and ream holes for the dowel pins shown, using the spacer block for alignment. They will sit flush or below the surface of the spacer so the bearing block will sit flat. The threaded holes for mounting the bearing block can be seen, but the reamed holes for the bearing block aren't drilled yet. Those will be drilled and reamed after alignment. The bearing block is shown in place below.

    Attachment 470960

    Holes for the pins shown will be drilled into the spacer after alignment. These won't go though into the casting. The two bolted joints together give a little bit of wiggle before being pinned.

    I have a centering laser I plan to use for alignment. A plug has been made that is a nice sliding fit in the bearing block. A 3/8" reamed hole holds the laser center. The parts are shown below.

    Attachment 470962

    Assembled into the bearing mount.

    Attachment 470964

    You can see the red laser dot on the apron. It isn't perfect so rotating the laser assembly scribes a small circle. That's OK though, the center of that circle is an accurate representation. So first align the tail stock so the "dot" doesn’t move up or down when the carriage moves. I can then drill the dowel pin holes to fix the bearing block. It seems the sideways alignment is already quite good, but if this proves to not be the case it can be shimmed. Actually, the vertical alignment seems very close just throwing the bearing block in place. Finally, once aligned, the laser will give center points for holes in the apron and head stock box. It’s starting to come together.

    Thanks.

    Hugh

  12. #52
    Join Date
    Dec 2005
    Posts
    91

    Re: PM1022 lathe CNC Conversion

    The box that fits onto the head stock end of the lathe is shown below.

    Attachment 471176

    It will hold the Z ball screw support and Z stepper motor. A timing belt will connect the two as described previously.

    The box replaces the gearbox on the original machine. That gearbox, like the apron gearbox, isn't needed for CNC operation. Once it's removed a flat mounting on the bed casting is seen.

    Attachment 471178

    The new box uses the same threaded holes in the casting as the original gearbox did. To align these holes I made a threaded center punch that threads into the casting. It has a point on the end that acts like a center punch.

    Attachment 471180

    I held the box in place and tapped with gusto leaving a center punch on the aluminum box. I drilled that hole, moved the punch, put the box in place, and inserted a screw in the new hole. Again tapping the box making the next hole. It was slower doing only one hole at a time but alignment is "assured". Finally I counter sunk these holes from the front side. It fits well.

    Now on to mounting the Z ball screw.

    Thanks.

    Hugh

  13. #53
    Join Date
    Dec 2005
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    91

    Re: PM1022 lathe CNC Conversion

    Busy times but I've completed the majority of the conversion. The first two pics show an overall view.

    Attachment 471182

    Attachment 471184

    In the last post I described mounting of the box at the head of the machine. The next two picturs show this mounted with the innards exposed. You can see the countersunk screws holding it to the casting.

    Attachment 471186

    Attachment 471188

    And the head box with its cover on. You can see the cooling fan on the front. On the right side the slots for belt tension adjustment are seen. Also seen on the right side the guide for the spiral spring screw cover. This holds the ID of the spring. The screw cover springs aren't shown as I still need to order them.

    Attachment 471190

    The carriage has the X axis drive pulleys and stepper motor. As per design, the motor is inboard to save some space. The slots for belt adjustment can be seen here. I do need to make a belt cover, and figure out how to mount it.

    Attachment 471192

    On the left side of the apron the recess for the screw cover spring is shown. This should allow the carriage to move up to the headstock without crunching the cover spring.

    Attachment 471194

    The Z axis nut is mounted on the right side of the apron. The round part most obvious is to hold the second screw cover spring. The small end of the spring fits over the tube.

    Attachment 471196

  14. #54
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    Dec 2005
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    91

    Re: PM1022 lathe CNC Conversion

    The other end of that cover spring fits into the recess screwed to the tailstock bearing block.

    Attachment 471198

    Finally, the other end of the bearing block.

    Attachment 471200

    As all projects I'm involved in, it didn't just "go together". I used the laser to align the tailstock bearing block. And then to center the holes in the apron and headstock box. This worked very well. I drilled the location holes for the bearing block after assembly. I did find, after mounting the bearing block and ball nut that the ball screw is not straight. I don't know how it could have been bent, it would take a significant force. But it goes together and will likely be OK. It will put an extra load on the bearings but they are oversized and, as a hobby machine, it will see light use.

    I did somehow cut the ball screw a little short. It all worked out, I think, but for a time I thought I'd made a catastrophic error. Maybe I will replace that bent screw after all. Otherwise the assembly went smoothly. There are a few details to complete, but that will always be the case.

    I did decided to leave out the inner spacer between the sets of angular contact bearings. I'll just pre-load the bearings with a locking nut rather than trying to get that spacer "just right". It should work well, it's what PM did in their PM728 conversion kit.

    I still need to put an encoder on the spindle for threading. Also the electronics need to be assembled. I have most of the components but haven't started building out this electrical box yet. Possibly home switches. But likely the next step is an enclosure to capture chips. I currently have good access to woodworking equipment and the enclosure will be primarily wood. I have no plan to use flood coolant so a wood enclosure, well sealed, will be OK.

    Doesn't seem to be many following along. But I'll post updates as I progress anyway.

    Thanks.

    Hugh

  15. #55

    Re: PM1022 lathe CNC Conversion

    Looks great! What control are you going with? Do you plan to stick with the stock spindle motor or go to something better?

    I've been following as I continue to gear up for my 1128 conversion. I am going to order my ball screws this week. The lathe has been super handy to have around just in manual operation, so I am sort of hesitant to tear it apart. The time is coming though.

  16. #56
    Join Date
    Dec 2005
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    91

    Re: PM1022 lathe CNC Conversion

    CL_MotoTech:

    I'm going with the easiest controller I can think of, at least for me. I'm going to use LinuxCNC with MESA 5i25 and 7i76 cards. These are for steppers and I used the same combination on my PM728 mill. I haven't hooked up an encoder or home switches using these cards but I know it's possible. I'm trying to buy a refurbished DELL computer from E-bay, but the process isn't foolproof.

    I started with the PM1022 for two reasons. I liked the spindle "quick connect" better than the threaded nose on other similar sized machines. The second reason is the T-slots on the cross slide. I wasn't thrilled that it came with a power feed cross slide. Very nice for a manual machine but a throw away for a conversion. The initial purchase decision was between a Grizzly G0752 and the PM1022. I believe the Grizzly has a 3 phase motor with VFD drive. But for the two reasons above, which can't be changed later, I went with the PM1022. The motor control on the PM seems a little off, it works OK but I'm not in tune with it yet. But I plan to run the original motor as long as it's adequate. If it's not I'll replace it all with a 3P motor and VFD, as many have done on these sized lathes.

    A couple of weeks ago I moved the little lathe from our winter place to our summer digs. Here I have a larger lathe which has made working on the PM much easier. That tear it down to measure, then put back together to make a part, then apart to test, repeat, gets real old real. Please let me know if you start a thread on your lathe conversion, I'd like to follow along.

    Thanks for the note. Good to know someone is coming along for the ride.

    Hugh

  17. #57

    Re: PM1022 lathe CNC Conversion

    Where did you source your ballscrews? I am leaning towards single nut eBay specials but I don't want to regret that choice.

  18. #58
    Join Date
    Dec 2005
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    91

    Re: PM1022 lathe CNC Conversion

    CL_MotorTech:

    I went through LinearMotionBearings2008 (e-bay) for my ball screws and nuts. I used a 20mm double nut (DFU2005 – 1000mm) for my Z, and a 12mm (RM1204 – 400mm) for the X. I got the X screw with two nuts hoping to arrange a double nut into the cross slide. When I got into the cross slide it was immediately obvious that two nuts wouldn't fit, it was a fight to get one in there. A double nut arrangement should give less backlash which is good.

    Thanks.

    Hugh

  19. #59
    Join Date
    Mar 2015
    Posts
    18

    Re: PM1022 lathe CNC Conversion

    Nice build. I have a PM 1127VF-LB that I have used manually for the last couple of years. Well its time to convert it to CNC. I will be following along to see you progress. Keep up the nice work. I've narrowed the ball screws to linearmotionbearings2008 & zyltech out of Texas. I think zyltech's ballscrews are all machined though. He gets good feedback 99.7% and has a lot of sales.


    Respectfully,
    D. Autry

  20. #60
    Join Date
    Dec 2005
    Posts
    91

    Re: PM1022 lathe CNC Conversion

    dautry:

    Thanks for the nice words. It's taken a little over a year so far but coming along nicely.

    I had good luck with linearmotionbearings2008, no experience with zyltech. I didn't think ball screws were machined? I'm familiar with rolled and ground, but not machined. The ground look real nice but cost buco bucks unless you find a deal on used.

    CL_MotoTech mentioned converting his 1128 lathe. I wonder if that is similar to yours? It could be a typo for an 1127, or a typo for an 1228. It would be nice to have a lathe slightly larger than a 10" but for me space is crazy tight.

    Will you start a thread on your build?

    Thanks.

    Hugh

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