Lathe Conversion, PM1228 to CNC


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Thread: Lathe Conversion, PM1228 to CNC

  1. #1
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    Default Lathe Conversion, PM1228 to CNC

    A few years ago I converted my G0704 mill to CNC and can use it it make most of the parts I need. However without a lathe, there is a lot of stuff I can't do. So I purchased a Precision Mathews 1228MV lathe. As a small manual machine, it's pretty good, but some of the parts I want to make have complex curves that are a pain on a manual machine. So, I found myself doing a conversion of it as well. Since I love looking at others photos of machines, here are mine.

    Here is a full shot of the system. The only thing remaining to complete is some software for the LCD panel on the console. I will be programmed to display the spindle speed and will set the switches for multiple functions.
    Lathe Conversion, PM1228 to CNC-2019-06-15-13-16-00-jpg

    Closeup of the cross slide. The RED parts are 3D printed parts. Mostly they are covers. The tube that goes from the front to back of the saddle is how I routed the cables to some electronics on the front of the saddle.
    Lathe Conversion, PM1228 to CNC-2019-06-15-13-16-20-jpg

    I built some covers for the cross slide ways and to cover the 1204 ball screw that replaced the manual lead screw.
    Lathe Conversion, PM1228 to CNC-2019-05-26-18-53-53-jpg

    I used ClearPath servo's on both Z and X axis. Both are direct drive. Z has a 1605 screw hidden under this cover. The Red object with the stainless socket screw is a carrier for the magnet that triggers the Z limit switch. It can slide back and forth so there is less chance of running the tool into the chuck.
    Lathe Conversion, PM1228 to CNC-2019-06-15-13-16-24-jpg

    There is the X Axis servo hiding on the back of the saddle under the cover. I used a cable drag track to get the wiring onto the saddle.
    Lathe Conversion, PM1228 to CNC-2019-05-28-14-48-16-jpg

    Designing and building the spindle encoder was the most difficult part of the conversion. The spindle has a 65 tooth gear that used to drive all the other gears on the head. I bought another gear and use it to drive a rotary encoder. Since I didn't want to make any new holes in the casting unless I had to, this is where it wound up. Unfortunately It sticks up above the top of the spindle housing so the cover door no longer fits. Oh well, who needs the safety covers anyhow.
    Lathe Conversion, PM1228 to CNC-2019-06-15-13-16-59-jpg

    Another shot of the encoder and a a completely clean spot where there used to be a bunch of greasy gears.
    Lathe Conversion, PM1228 to CNC-2019-06-15-13-16-49-jpg

    A quick and dirty AXA tool rack.
    Lathe Conversion, PM1228 to CNC-2019-05-28-14-50-56-jpg

    I will put the electronics in another post.

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    Lathe Conversion, PM1228 to CNC-2019-06-15-13-16-20-jpg   Lathe Conversion, PM1228 to CNC-2019-05-26-18-53-53-jpg   Lathe Conversion, PM1228 to CNC-2019-06-15-13-16-24-jpg   Lathe Conversion, PM1228 to CNC-2019-05-28-14-48-16-jpg  



  2. #2
    Community Moderator Jim Dawson's Avatar
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    Default Re: Lathe Conversion, PM1228 to CNC

    Nice Job!

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: Lathe Conversion, PM1228 to CNC

    What a stunningly clean conversion. Beautiful work. Would also love to see the electronics enclosure.



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    Default Re: Lathe Conversion, PM1228 to CNC

    Some more photos when the machine was more naked.

    X Axis ballscrew was a pain to get it installed with clearance for the nut. I would have liked to use a 1605 screw but there was no way that nut would fit in that cavity. 1204 is hopefully enough.
    Lathe Conversion, PM1228 to CNC-2019-04-04-14-43-50-jpg

    This replaced the gearbox on the front of the saddle.
    Lathe Conversion, PM1228 to CNC-2019-04-04-14-42-54-jpg

    I have not installed it yet, but there will eventually be a ballnut on this side of the saddle as well to get to zero backlash.
    Lathe Conversion, PM1228 to CNC-2019-04-04-14-42-58-jpg

    Here is a closeup of the spindle encoder carrier.
    Lathe Conversion, PM1228 to CNC-2019-04-17-11-40-47-jpg

    Attached Thumbnails Attached Thumbnails Lathe Conversion, PM1228 to CNC-2019-04-04-14-43-50-jpg   Lathe Conversion, PM1228 to CNC-2019-04-04-14-42-54-jpg   Lathe Conversion, PM1228 to CNC-2019-04-04-14-42-58-jpg   Lathe Conversion, PM1228 to CNC-2019-04-17-11-40-47-jpg  

    Last edited by maxspongebob; 06-20-2019 at 04:41 PM.


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    Default Re: Lathe Conversion, PM1228 to CNC

    The electronics enclosure. The brains are an Ethernet Smooth Stepper. The interface cards on the lower left are my own design. Each card handles a function and converts the signals to the ESS. There is a board for the limit/home switches, servo control, spindle/encoder interface, and Console interface. All the internals run off a single 12Volt DC supply.
    Lathe Conversion, PM1228 to CNC-enclosure-jpg

    The door of the enclosure has the main power switch E-Stop and a power monitor display.
    Lathe Conversion, PM1228 to CNC-2019-05-28-14-49-40-jpg

    Attached Thumbnails Attached Thumbnails Lathe Conversion, PM1228 to CNC-enclosure-jpg   Lathe Conversion, PM1228 to CNC-2019-05-28-14-49-40-jpg  


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    Member propeine's Avatar
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    Default Re: Lathe Conversion, PM1228 to CNC

    You make it look so easy! Almost makes me want to tear down my Southbend.



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    Default Re: Lathe Conversion, PM1228 to CNC

    Enclosure looks great! Nice work, very professional.



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    Default Re: Lathe Conversion, PM1228 to CNC

    Finished. I put the safety cover back on.
    Lathe Conversion, PM1228 to CNC-2019-06-24-17-54-32-jpg

    Now all I have to do is teach myself how tool and fixture offsets work and I will be good to go.

    Attached Thumbnails Attached Thumbnails Lathe Conversion, PM1228 to CNC-2019-06-24-17-54-32-jpg  


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    Community Moderator Jim Dawson's Avatar
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    Default Re: Lathe Conversion, PM1228 to CNC

    I think that is the nicest looking conversion I have ever seen. Great job!

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: Lathe Conversion, PM1228 to CNC

    Have you ever cut with the lathe yet ? How fast x axis with 1204 ballscrew ?



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    Default Re: Lathe Conversion, PM1228 to CNC

    Quote Originally Posted by asuratman View Post
    Have you ever cut with the lathe yet ? How fast x axis with 1204 ballscrew ?
    I have done a few delrin cuts but nothing to push the machine. I think as far as speed, I will be limited most by the spindle. The max I can get from it is 1300 RPM so my surface speed won't be huge. The servo's max RPM I have set to 1000 so that puts rapids at 150 IPM on X and 175 on Z. The mechanicals could probably do twice that but I found that the Z ballscrew starts to flap around 2000 RPM.

    Currently I am chasing problems with the Brushless DC motor. When I repurposed the motor I found that the phase cable was just long enough to reach inside the cabinet. Unfortunately about half the cable doesn't have a shield on it and this is generating a lot of noise on the electronics inside the cabinet. I have some more cable on order along with some ferrite chokes. Those will be in tomorrow and I can, hopefully, solve that problem. I found this out when I updated the code in Mach so that it monitors the motor error feedback signal. The feedback, if bad, will stop all motion of the servos.

    So when I get back up and running I will do some tests to see what it's limits are and report back.



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    Default Re: Lathe Conversion, PM1228 to CNC

    Quote Originally Posted by Jim Dawson View Post
    I think that is the nicest looking conversion I have ever seen. Great job!
    Thank you Jim. It has taken a while to complete and all along I was wondering if I was going to miss my manual lathe. We shall see.



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    Default Re: Lathe Conversion, PM1228 to CNC

    Quote Originally Posted by mcardoso View Post
    Enclosure looks great! Nice work, very professional.
    Thanks.



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    Default Re: Lathe Conversion, PM1228 to CNC

    A few days ago, I found that my servos were sending an error signal whenever the spindle would start up. With a bit of help from a digital oscilloscope I traced the problem down to noise on the step signal to the servo. In my system I am using ClearPath servos that have the controller built into the motor, so the Step/Dir signals are sent directly to the motor.

    The servo was seeing a very short spike on the line and was triggering this as an error. Since I had programmed Mach 4 to halt motion if it saw an error from a servo, this was shutting the whole system down.

    What I found:

    Since I was using the original Brushless DC motor from the lathe, I had installed a controller for it. The logical place to put the controller in the electronics enclosure was on the inside of the door. This worked out well with plenty of clearance all around.
    Lathe Conversion, PM1228 to CNC-2019-06-27-12-10-11-jpg

    What I found was that when I built the box I had installed a small wire from the box to the door to ground the door. Well, that wire wasn't cutting it. The stud I attached to was covered in paint so there was little if any actual connection. So I installed the wire strap you see in the picture below and made sure it was properly connected. Problem solved.

    Lathe Conversion, PM1228 to CNC-2019-06-27-12-09-57-jpg

    Attached Thumbnails Attached Thumbnails Lathe Conversion, PM1228 to CNC-2019-06-27-12-10-11-jpg   Lathe Conversion, PM1228 to CNC-2019-06-27-12-09-57-jpg   Lathe Conversion, PM1228 to CNC-2019-06-27-12-09-57-jpg  


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    Default Re: Lathe Conversion, PM1228 to CNC

    I have made my last changes for a while. I added a Z and X MPG for jogging.
    Lathe Conversion, PM1228 to CNC-2019-06-28-15-36-57-jpg

    Also organized the cabling in back.
    Lathe Conversion, PM1228 to CNC-2019-06-27-12-16-15-jpg

    Attached Thumbnails Attached Thumbnails Lathe Conversion, PM1228 to CNC-2019-06-27-12-16-15-jpg   Lathe Conversion, PM1228 to CNC-2019-06-27-12-16-15-jpg   Lathe Conversion, PM1228 to CNC-2019-06-28-15-36-57-jpg   Lathe Conversion, PM1228 to CNC-2019-06-28-15-36-57-jpg  



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    Default Re: Lathe Conversion, PM1228 to CNC

    First Cut. I wasn't prepared for that long stringy chip. I didn't get those with the manual lathe. I need a chipbreaker insert.





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    Default Re: Lathe Conversion, PM1228 to CNC

    Very nice conversion, but one question: why do you still use the compound slide? There's really no need for it with CNC and using just a solid spacer would make the QCTP more rigid.



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    Default Re: Lathe Conversion, PM1228 to CNC

    Quote Originally Posted by Stigoe View Post
    Very nice conversion, but one question: why do you still use the compound slide? There's really no need for it with CNC and using just a solid spacer would make the QCTP more rigid.
    I just haven't gotten around to replacing it yet. My mill is a G0704 and I am not sure that it could handle whittling down a chunk of steel that big. This is what I have in mind.

    Do you think that using Aluminum would be acceptable?

    Lathe Conversion, PM1228 to CNC-compund-block-jpg

    Attached Thumbnails Attached Thumbnails Lathe Conversion, PM1228 to CNC-compund-block-jpg  


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    Default Re: Lathe Conversion, PM1228 to CNC

    why do you still use the compound slide?
    It helps you zeroing tools ...



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    Default Re: Lathe Conversion, PM1228 to CNC

    Thanks! I need it



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