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Taking the CNC Plunge

Discussion in 'PRECISION-MATTHEWS' started by TomS, Aug 6, 2014.

  1. TomS

    TomS Active User H-M Supporter-Premium

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    I found your schematic last night, couldn't remember where I first saw it, and studied it thoroughly. Bear with me as electricity is not my strong point. If I understand your logic the factory supplied for/rev switch is still used to control spindle direction. I understand the function of the two momentary switches; one for On and one for Off. Is this correct? Is the symbol in the wire between forward and reverse a diode?

    For info my mill is CNC but will manually be changing speed and spindle direction until I move onto phase 2. Phase 2 will be a ESS and spindle control board upgrade.

    Til the next onslaught of questions, thanks for your help.

    Tom S.
     
  2. TomS

    TomS Active User H-M Supporter-Premium

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    Tim - your input is appreciated. I've got four wires coming from my for/rev switch. Are you saying two go to P24, one goes to terminal 1 and the remaining one goes to terminal 2? Sorry for any stupid questions but I want to make sure I don't fry the VFD because I mis-wired something.

    Yes, my plan is to add a fan to the enclosure. Got it on the P1/P2 leads. Seems simple enough.

    Tom S.
     
  3. jbolt

    jbolt United States Active User H-M Supporter-Premium

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    Not sure if the picture of the VFD in the box is the way you intend to mount it but you will want the control panel facing you for programming etc.
     
  4. TomS

    TomS Active User H-M Supporter-Premium

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    Unfortunately that's the only way it will mount. It's a 12" x 12" x 6" enclosure. I opted to go with this enclosure because it was in stock locally. My mill has been down for a month and I want to get it running. Worst case is I leave the wiring a bit long and do the programming with the VFD out of the enclosure. The screen is visible and I can get to the buttons the way it is. Thankfully I only have to program it once.

    Tom S.
     
  5. TomS

    TomS Active User H-M Supporter-Premium

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    Thanks to mksj and others I've got my VFD wired. Next step is to wire the motor but I can't do that until I get the spindle grease so I can assemble the spindle. I'd like to do the VFD programming while waiting for the grease but I think I heard that you can't run the VFD unless it's connected to the motor. Is this true?

    Tom S.
     
  6. TomS

    TomS Active User H-M Supporter-Premium

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    Success, at last. Got my spindle together and installed and ran it with the belt. No abnormal issues except a rattle coming from the spindle. It's the spindle spline rattling in the drive sleeve. I know it's the spline and drive sleeve because when I tighten the spindle lock the rattle becomes louder. I ran for 15 minutes at 900 rpm, then another 15 minutes at 1800 rpm, then ramped up to 3600 rpm and finally a run of 6400 rpm for another 15 minutes. Highest measurable temp was 103 deg. F at the drive sleeve bearings. It also whines a bit but my understanding is this is normal. I seem remember there is a parameter setting that helps to reduce the whine.

    I got a over-voltage error when I quickly turned the pot down from 90 hz to 0 hz. It's got something to do with dynamic braking I'm sure. I'll look through the parameters and figure out which one to change. I'll try it with no braking and see how long it takes to coast down.

    All in all a great learning project. Thanks to MKSJ (Mark) and several others for chiming in with answers and suggestions. I would not have taken on this project without their help and guidance. I've attached the files MKSJ sent me so that others can see what I did. Hopefully it will help someone else. I tried uploading a short video of the mill running at 6400 rpm but the file is huge. I'll see what I can do about reducing the file size.

    Tom S.

    KM2 and KM3 are no longer there nor is the DC Z axis lift motor.
    VFD Wiring Diagram.jpg
     

    Attached Files:

  7. jbolt

    jbolt United States Active User H-M Supporter-Premium

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    Awesome!
     
  8. TomS

    TomS Active User H-M Supporter-Premium

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    Thanks. Can't wait to take some trial cuts to test the bearing preload. Maybe tomorrow if the grandkids go away. LOL

    Tom S.
     
  9. tmarks11

    tmarks11 Active User Active Member

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    If you install an external braking resistor ($20-30 on eBay), it will help the rapid deceleration. You would be able to stop the spindle in less than a second.
     
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  10. jbolt

    jbolt United States Active User H-M Supporter-Premium

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    I had the spline rattle and fixed by greasing it.

    I don't use electronic breaking with spindle controlled from Mach3. There is enough drag with the belt drive to slow it down quickly enough. I do like it on the lathe though.
     
  11. TomS

    TomS Active User H-M Supporter-Premium

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    Thanks for the tip on greasing the spline. I'll give it a try.

    I was thinking along the same lines as you on electronic braking. I've looked through the parameter list and there are several that address overvoltage fault error. I'm going to change them one at a time and see what effect they have on decel time and if I still get the dreaded overvoltage fault.

    Tom S.
     
  12. TomS

    TomS Active User H-M Supporter-Premium

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    Thought about a resistor but this project has stretched my electrical skills to the max. For the moment I'm going to play with the deceleration features and see if I can get around the overvoltage fault by increasing the decel time. Phase 2 will be an upgraded BoB, ESS, and spindle control board. I'll look at it again when I do Phase 2.

    Thanks,


    Tom S.
     
  13. TomS

    TomS Active User H-M Supporter-Premium

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    This is my first time uploading a video. It is a clip of my mill running at 6400 rpm (90 hz) after completing the VFD/belt drive conversion. Sure beats a top speed of 1970. Not sure why it turned 90 deg. or how to correct it. File size started out at 63 mb. Got it down to 4 mb. Still have some fine tuning to do and a few details to finish up. If you listen closely you can hear the spindle spline/drive sleeve rattle I mentioned in my post above.

    Tom S.
     

    Attached Files:

  14. Davd Flowers

    Davd Flowers United States Active Member Active Member

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    Maybe I missed it, but how is the driven pulley attached to the spindle? Awesome thread BTW....
     
  15. TomS

    TomS Active User H-M Supporter-Premium

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    Thanks for the kinds words. As most others have done when converting their mills to belt drive I modified the splined sleeve (part 57) on the attached drawing by machining off the gear and cutting a snap ring groove to retain the pulley. Some have threaded the end of the sleeve for a retaining nut. The sleeve is then assembled inverted from it's original orientation. See the picture below of the finished sleeve.

    Tom S.

    20161205_153916_resized.jpg
     

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  16. Davd Flowers

    Davd Flowers United States Active Member Active Member

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    OK, I think I see.
    The pulley is pressed and keyed to the splined coupler, but then does it just sit over the spindle shaft or is there any type of bearing support on it?
     
  17. TomS

    TomS Active User H-M Supporter-Premium

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    There are two ball bearings and a spacer that support the sleeve. These pictures are not of my assembly but illustrate how it's done. You will see that this assembly has inner and outer bearing race spacers. That's because a retaining nut is used to compress the bearings against the lower snap ring. Here are a few pictures of the sleeve assembly and installation.

    Let me know if you need more info.

    Tom S.

    Individual components that make up the assembly. Note that this picture shows a retaining nut at the top. My assembly uses a snap ring and no inner bearing race spacer. See the snap ring between the two bearings? That fits into a groove in the bearing bore of the cover plate and retains the sleeve assembly in the cover plate.
    gdmP1030063.JPG

    Here are the components assembled on the sleeve for illustration only. To assemble the parts in the cover plate you first install the snap ring in the bearing bore, then press in the bearings. Drop in the bearing spacer(s), slip the sleeve into the bearings, install the key and pulley and tighten the nut or in my case install the upper snap ring.
    gdmP1030062.JPG

    The sleeve assembly, minus the pulley installed in the cover plate.
    gdmP1030080.JPG

    Bottom view of the cover plate.
    gdmP1030081.JPG
     
  18. Davd Flowers

    Davd Flowers United States Active Member Active Member

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    OK, I got it now :)
    Thanks for taking the time to show me.
     
  19. TomS

    TomS Active User H-M Supporter-Premium

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    Glad to help.

    Tom S.
     
  20. Davd Flowers

    Davd Flowers United States Active Member Active Member

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    Im thinking that this is a mod I want to do sooner than later :) Now if only my ball screws would hurry up and get here!
     
  21. TomS

    TomS Active User H-M Supporter-Premium

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    It's worth doing sooner than later. Machining aluminum with a 1/4" carbide end mill at 1970 rpm will test your patience. I've had my mill running under CNC for about 1-1/2 years and immediately saw a need for higher rpm. Should have listened to recommendations by others on this site but went the auxiliary spindle route and soon discovered that, although workable, didn't work well machining steel and end mills larger than 1/4". Good luck with your conversion and please post pictures. We're voyeurs when it comes to machinery.

    Tom S.
     
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  22. Davd Flowers

    Davd Flowers United States Active Member Active Member

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    I know all too well about having patience. The g0704 lacks rpms as well, and its lack of rigidity keeps it from swinging the larger endmills I can run in my bridgeport. I added a auxiliary spindle to it, but that was for running a .010" endmill for some engraving work. I apologize for the bit of a thread derail, but offer some pics as atonement.
    20161107_123933.jpg
    20161206_162425.jpg
     

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  23. TomS

    TomS Active User H-M Supporter-Premium

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    Nice medallion! I've got a couple of hot rods. What do you have?

    Here's a pic of my auxiliary spindle.

    Tom S.

    20151110_085830.jpg

    Super PID speed controller gets me down to 5000 rpm.
    20151211_114520_resized.jpg
     

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  24. Davd Flowers

    Davd Flowers United States Active Member Active Member

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    This is my current project....
    20160511_102056.jpg
    20160911_135524.jpg
    20160915_192230.jpg
     

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  25. Davd Flowers

    Davd Flowers United States Active Member Active Member

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    This is my Dads, we finished it up a couple years ago.
    20151213_114952.jpg
     

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  26. TomS

    TomS Active User H-M Supporter-Premium

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    Nice cars! Really like the 40. Built a few over the years too. These are my current wheels in storage for the winter.

    Built in 1996. Had so much fun in it we wore out the first engine.
    20170120_130650_resized.jpg

    This is the work in progress. Mechanically done. Paint and interior next on the agenda.
    20170120_131205_resized.jpg
     

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  27. Davd Flowers

    Davd Flowers United States Active Member Active Member

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    Nice, I especially like the 32 :)
     
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  28. TomS

    TomS Active User H-M Supporter-Premium

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    I've had my VFD and belt drive conversion running for a few months now and am pleased with the results. Speeds and feeds are now where they should be and surface finishes are improved as are machining times. Now it's time for phase 2 of the conversion: PMDX-126 BoB, PMDX-107 spindle control board and ethernet smoothstepper.

    I've got the BoB, spindle controller and ESS mounted in an enclosure and currently wiring the components. Thank God for Google! Pictures to follow. One question I have is in regards to wiring my drivers (DQ860MA and DQ2722) to the BoB. I've got the step, direction and com wiring figured out but the enable wire from the driver has me puzzled. I've read the PMDX manual several times as well as the AN002 bulletin and associated flyer on whether to enable or not to enable. From what I understand the enable signal is a 5vdc signal to the driver to lock the motors in position during startup. Is this correct? If yes, then I can connect the enable wire to the PC+5V terminal at the BoB? Am I on the right path?

    I'm sure more questions will come up as I work my way through.

    Thanks,

    Tom S.
     
  29. jbolt

    jbolt United States Active User H-M Supporter-Premium

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    Sorry Tom I cannot help. I don't use the enable wire on my machines. Never saw the need.

    I believe you use the "PC ground" on the connector but I'm not sure how you set that up.

    You might try searching the PMDX forums or posting a question. Steve is pretty good at responding.
     
  30. TomS

    TomS Active User H-M Supporter-Premium

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    Thanks Jay. I was hoping you saw my post. Nothing on the PMDX forums relating to my question. I'll sign up and post it there.

    I've got the wiring done. Next steps are to make sure the jumpers and dip switches are set correctly and double check my wiring. Then it's onto Mach and ESS configuration and testing. I'm sure I'll have more questions.

    Tom S.
     

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