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rung fu clone RF-45 ZX45 cnc conversion

Discussion in 'MACHINE BUILD LOGS' started by jumps4, Aug 22, 2012.

  1. jumps4

    jumps4 Global Moderator Staff Member Active Member

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    I was lucky that i had a small mill to make my parts with so i didnt have to use the zx45, that would have been a real pain.
    good luck with your project and let me know if i can help with anything
    steve
     
  2. jumps4

    jumps4 Global Moderator Staff Member Active Member

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    I have not posted anything about my mill in some time because there really wasnt anything to add.
    but today i had decided it was time to take the time to locate some backlash it has been gaining.
    i first removed all the bellows and covers to see the ways and clean them. there was still plenty of oil on everything and no swarf. i exspected to see some gray in the oil i was wiping off from the machine breaking in but the oil was really clean and no sign of any wear or scratches on all of the ways. so i relubed and rechecked the gib adjustment using the tormach method. you loosen everything so there is no friction. check your backlash writing it down then begin adjusting the gibs until the backlash starts to increase more and more as you snug it. back off just until you reach the first measurement and lock it down. it seemed to work well there is no gib play.
    i then moved the indicator around to check to see where the backlash was:
    on the y axis the mounting bolt for the ballnut mount was loose( i probably missed this being really tightened when i was building it ) and the thrust bearing needed a little adjustment. backlash went from .014 to .0015 all in the ballnut.
    x axis needed the preload on the thrust bearing adjusted the set screws were not tight enough and it backed off. after setting preload it was back to .002 and all in the ballnut so that was good.
    mach3 compensates for this amount just fine
    z axis i lubed everything checked the gib and mounting screws and didnt disassemble the bearing mount to set preload because it is only .004 and i'll take that all apart another day for adjustment.
    so far I'm still really happy with all of these cheap parts and everything is working very well
    steve
     
  3. jumps4

    jumps4 Global Moderator Staff Member Active Member

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    I had a request for pics of how the nema42 motor was mounted to the top of the z axis and posted them here.
    everything has still worked perfect and no mods have been made to date.
    steve

    DSCF0745.JPG DSCF0746.JPG
     
  4. Blackhawk

    Blackhawk United States Active User Active Member

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    Thanks Steve,

    that clears everything up. The cap on the top of my mill only had three screws holding it on so I was wondering how to go forward.



    lanham
     
    Last edited: May 27, 2013
  5. jumps4

    jumps4 Global Moderator Staff Member Active Member

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    the 4 motor bolts go through the mounting plate and are drilled and tapped into the top of the column.
    i had to grind the hole in the top of the column to make it rounder. to do that i used a grinding stone in a wood router. it worked well but be carefull if you try it that your stone is rated for the rpm.
    steve
     
  6. Blackhawk

    Blackhawk United States Active User Active Member

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    I was wondering about that, mine looks like they used a chisel and hammer to make the hole:lmao:

    lanham
     
  7. 109jb

    109jb United States Swarf Registered Member

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    Hi there. New user here. First let me say that this is a great thread and you have a great build. I currently have a Grizzly G0704 converted to CNC, but want bigger. I am looking at getting a RF45 clone and doing similar to your build. I see from the posts that you used the motor kit with the 4200 oz-in Nema 42 and the DQ2722M driver for the Z-axis and 1600 oz-in NEMA 34 and DQ860MA drivers for the X and Y. That said, I have a few questions I hope you can answer.

    1. I don't see a lot on the DQ2722M driver and I'm not sure how it works. Since it has AC input, I suppose it must rectify the AC into DC before the driver section. Do the specs say anything about what DC voltage is supplied to the motor?

    2. Have you had any problems with the stepper/driver combo (Other than the broken wire I saw).

    3. How smooth are the motors? For example do any of the motors exhibit a great deal of mid-band resonance?

    4. I may have missed it, but what size ball screws did you use on X, Y, and Z axes?

    Thanks for posting your build!!
     
  8. jumps4

    jumps4 Global Moderator Staff Member Active Member

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    hi 109jb and thank you for your compliments

    1. the dq2722m is 80v output I believe. the unit has its own power supply built in and works great. if they were not so costly i'd use them on everything.

    2. everything has been working perfect with no mods since I built it... I have a friend that is about to start his own copy and there are no planned changes.

    3. because of the excess power I have I was able to use a higher microstep so the motors are really smooth and quiet. no resonance in the speeds I operate at, I can run at 200ipm with no problems but I have everything set to 100 max for safety.

    4. the ebay ballscrew set is item number 290649528399 and is 20mm on the z and 16mm on x and y. the bearing blocks in the kit required a shim to get a preload on the bearings and I have had that same problem on other kits I have bought. It's and easy fix.

    any other questions feel free to ask
    steve
     
  9. Bernie_nor

    Bernie_nor Norway Iron Registered Member

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    Re: rung fu clone RF-45 ZX45 cnc conversion - question regarding motor size

    Hello All,

    I've read this thread with great interest! I've got a ZX45, and from what I can see it's identical with jumps4s RF45. I'm in the process of planning my own conversion. I think I will build it pretty much the same way as described here. It seems so fasinating simple compared to other conversion I've read about. Great work on both the construction and the build!

    My first (of many) question:
    Now that you havre run this machine for a while, do you think the size of the motors is suitable? Or put another way: Can I get away with smaller motors? What would in that case be a suitable size?


    Cheers!
    Bernie



     
    Last edited: Nov 13, 2013
  10. jumps4

    jumps4 Global Moderator Staff Member Active Member

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    hello Bernie
    I have been using this machine without issue for over a year and to date there is not one thing I would change. The motor size has guaranteed repeatability and precision. I have never had a motor miss steps no matter the speed or cutting load I'm running. there is no heat problems in the motors.
    If you want a really nice conversion that's not just a hobby light duty toy, don't cut cost on the motors you can keep the gibs snugged right up on this machine and hold some really close tolerances. After hours of running it will return exactly to zero and that means it has never missed any steps.
    good luck with your build
    steve
     
  11. Bernie_nor

    Bernie_nor Norway Iron Registered Member

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    Re: zx45 milling machine cnc conversion

    What was the size of the motors originaly?
    (Nena 34 and Nema 43, but what was the torque?

    The information is no longer available om Ebay.


    Cheers!
    Bernie
     
  12. jumps4

    jumps4 Global Moderator Staff Member Active Member

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    here is a pic of the 3 axis motors I used. I purchased another motor, power supply and driver for the 4th axis.
    the EBay item number is " 140906996891 " It has a nema 42, 4200 oz/in motor for the z axis and nema 34 1600 oz/in motors for the x and y. I used a nema 34 870 oz/in on my 4th axis.
    steve

    $(KGrHqF,!o0E8VU4wM6!BPU3K1lv!Q~~60_57.jpg
     
  13. jumps4

    jumps4 Global Moderator Staff Member Active Member

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    also the breakout board that comes with the motors is useless, the optocouplers are too slow for any micro-stepping and speed. I used this 5 axis board, EBay item # " 280965437859 " and a UC100 usb controller from cnc4pc.com. I can run at speeds up to 200 in per minute if I wished. I keep rapids set to 100 max for safety. the 300lb Z axis headed down at the table at 200 ipm scares the heck out of me lol
    steve
     
  14. Bernie_nor

    Bernie_nor Norway Iron Registered Member

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    Thanks a Lot Jumps4!

    I'm not sure when I'll be ordering the ballscrews and the motors. At the moment my liquidity is a bit low. But hopfully it'll improve in the next few weeks. Have sold a share in another project and that shuld be sufficient to finance this one. If the buyer is paying that is.

    I'm planneing on using this USB interface: http://www.edingcnc.com/index.php?pagina=detail_producten&productenid=51 A friend of mine is using this on two machines. And he can help me out when I get stuck.



    Bernie
     
  15. Bernie_nor

    Bernie_nor Norway Iron Registered Member

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    Ballscrews and nuts are ordered: Will arrive before Christmas!
    Total cost 156$ pluss shipping (69$). And this is with the screws machined according to my specifications.


    I'm not planning on making a build thread here for my conversion. As I'm already having a build thread on a blog (in Norwegian).


    Cheers!
    Bernie
     
  16. jbolt

    jbolt United States Active User H-M Supporter-Premium

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    Jumps4,

    Very nice thread.

    I'm curious how you arrived at using 16mm ballscrews for the X, Y and 20mm for the Z. I have been reading about other RF45 clone conversions and some have used 20mm on the X,Y and 24mm on the Z.

    Have you counterbalanced the gear head at all? If not have you seen any wear on the Z ballscrew?

    On the Z ballscrew, what bearings did you end up using? That part was not clear to me.

    Thanks for taking the time to post all the information.

    Jay
     
  17. jumps4

    jumps4 Global Moderator Staff Member Active Member

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    hi jay
    the X and Y ballscrews are 1605's because of the close opening between the y and x axis. there is not room for the 20mm ballnut without removing a lot of material from the underside of the table. I had to remove some to fit the 16mm.
    The bearing I used for z is the same type as x and y except in a square block and larger.
    attachment.php?attachmentid=40268&stc=1&thumb=1&d=1384893085.jpg
    the entire head weight is held by the screw and no lift cylinders are needed with the 4200oz/in motor. So far i have had no issues with any axis except to go back and reset bearing preload because i didn't tighten the set screws on the retaining nuts tight enough.
    I use this mill almost every day for hours without any problems. backlash is running a about .002 - .003 and mach3 comp takes care of that. nothing on the mill or screws has shown any sign of wear so far. I use marine grease in the ballscrews and way oil on everything else.
    One thing i did learn was to not overtighten the ways, to get everything set correct I had to loosen the ways, set my preloads and measure the backlash and write it down. then adjust each gib untill the backlash increases and then back off just untill it stays the same. any more and your not measuring backlash correctly because it included the torque required to overcome the gib tension, and it will through everything off. the table is actually snapping into the next position if too tight.
    thanks for looking
    steve
     

    Attached Files:

    Last edited: Dec 13, 2013
  18. jbolt

    jbolt United States Active User H-M Supporter-Premium

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    Thanks Steve,

    I have noticed that on the other builds with 20mm screws did have to remove material under the table. If the 16mm is working for you then it sounds like the way to go.

    I take it the bearings were supplied with the ballscrew kits?

    I won't have my mill for a couple weeks and then I won't be doing the conversion until after the high school robotics season ends in April.

    Do you mind if I pick your brain about your low voltage setup as I get into building the controls?

    Jay
     
  19. jumps4

    jumps4 Global Moderator Staff Member Active Member

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    I'd be happy to help jay
    start a thread in the cnc section here and i'll post any information you may need including wiring diagrams there.
    using the words zx45, rf45 and cnc conversion in the title will also draw in other people to your thread who are searching the web
    steve
     
  20. jbolt

    jbolt United States Active User H-M Supporter-Premium

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    Bernie,

    What did you order and from whom? My mill is not here yet to measure and I am curious what lengths are needed for each axis.

    Thanks,

    Jay
     
  21. Bernie_nor

    Bernie_nor Norway Iron Registered Member

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    I ordered the screws from a ebay seller http://stores.ebay.co.uk/linearmotionbearings But I did not order the standard sets. I made a specification and sent it to them for qoute. The specifications can be read here: http://www.omegav.ntnu.no/~hembre/Ballscrew_specification_20131129.pdf

    Please note, the lengths vary from model to model among the ZX-45 clones. And my Y-axis is to long. But at the time of ordering I was not sure how it would work out. So I ordered a longer screw than what is needed. I have extended the travle on Y the same way as Jumps4 has. My only consern regarding the Y axis is if the free moving end is to long. But I don't think that will be a problem. On the free moding end of the X-axis I'm planning on putting the original handle. That way I can use the mill in manual mode untill I have sorted out the wiring of the steppers.

    I have redrawn all the drawing for the X and Y with the exception of the ballnut holders. I have not desided on how to do the Z-axis yet. Main reason for redrawing everythin was to get good drawings for manual making the parts. I do not have access to a CNC, so all the parts are made on the ZX-45. And also I wanted to get everything metrical. :). Tha DXF provided by Jumps4 was a great starting point. I can add my new drawings here if you are interested.


    Cheers
    Bernie
     
  22. jbolt

    jbolt United States Active User H-M Supporter-Premium

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    Bernie,

    Thank you for the link to the ebay seller and the PDF. It helps me to get an idea of how long the screws need to be. As my machine is a different brand I think I will wait for it to arrive so I can get the exact dimensions.

    I noticed you ordered two ball nuts for the Y axis and only one for the others?

    Best of luck with your conversion!

    Jay

    - - - Updated - - -

    Steve, thanks for offering to help. I can do that but I am mostly interested in the low voltage wiring with the switches and relays for the power supplies, spindle, 4th axis and coolant system.

    If you think it is best to start a new thread for that, I will when I have the power supplies, stepper drivers and breakout board installed and wired.

    Thanks,

    Jay
     
  23. Bernie_nor

    Bernie_nor Norway Iron Registered Member

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    Funny you noticed to extra ball nut, the seller didn't... Got mye ballscrews today. But without the supporting ball bearings. Was my description unclear for you guys to? I intended to ordere 2 BK-12, one BF12 and one BK15 ball bearing supports.

    My idea with the extra ballnut was to have one spare. And to have one I can use as template when I (mayby in the future) will add one more for additional backlash elimination.

    Jumps4: Do you have any backlash at all on the Z-axis?


    Cheers!
    Bernie
     
  24. jbolt

    jbolt United States Active User H-M Supporter-Premium

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    It was clear to me! Looking at other conversions I see some use two ball nuts or double-nuts on each axis to zero out any backlash. That's my plan for the X & Y but I'm not convinced the Z needs it. My current plan is to counter balance the head with upward bias.

    Jay
     
  25. Bernie_nor

    Bernie_nor Norway Iron Registered Member

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    It was clear to the seller as well, the missing parts are on they way. That way I should be able to make all the other parts before the bearings arrive.

    The reason for not having any backlash on the Z-axis is because the weight of the milling head offsets the forces causing the backlash. But it only offsets them by a force equal to the weight. I'm guessing the milling head weights about 150-160. So if there are forces larger than this on the Z-axis (upwards) there will be movement/backlash. If you offset the weight of the Z-axis, I think you reduce this margin. Given the low price on the NEMA42 stepper and the simplicity of Jumps4's design I think this is the best way to solve this for me.

    But I'd like to work out a better solution with less backlash on X and Y. The plan is to build the X and Z axis fisrt. Then use the 2 axis CNC to machine the parts for the Z-axis. And if/when I desided to reduce the backlash I will machine new parts or modify the parts I have for the X an Y ball-nut with the addition of a extra set of nuts.

    My motors should arrive today og tomorrow. Christmas come early this year :)



    Cheers!
    Bernie
     
  26. Bernie_nor

    Bernie_nor Norway Iron Registered Member

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    Hi Steve,

    How much of the backlash do you think i caused by the ballnut? And is there any backlash caused by the couplings for the motor, as they are a bit flexible when it comes to torque?

    I have ordered this couplings: http://www.ebay.com/itm/37072451129 (For X and Y). I guess it is similar to the ones you are using. Do the axles meet inside the coupling, or do the have to be a bit apart? If they have to be a bit apart, how much is it? I'm making the spacer plates between the plate holding the stepper and the plate holding the bearing now, and am curios how long these have to be.


    Cheers!
    Bernie
     
  27. jumps4

    jumps4 Global Moderator Staff Member Active Member

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    hi Bernie
    I tried to look up the ebay item number and it must be a typo I could not find it in ebay
    I had a problem with the spiral cut couplings because they would coil like a spring under torque so that is why I use the plate type.
    the closer to perfectly aligned the motor and shaft are the less critical the gap between the 2 shafts become. I set mine at an 1/8". some brands of couplings do not have the bore larger in the center and require a longer gap so they will flex.
    I hope that helps
    steve
     
  28. Bernie_nor

    Bernie_nor Norway Iron Registered Member

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    Hi,

    The link got cut off in my editing of the post. This one should work: http://www.ebay.com/itm/370724511297

    1/8" sounds good to me. I might add a little to the Y-axis as I have extended it slightly and need the extra room between the stepper and the Mill itself.


    Cheers!
    Bernie
     
  29. jumps4

    jumps4 Global Moderator Staff Member Active Member

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    the best I can get out of the ballscrews I bought from china is .002. for my needs and the fact mach3 compensates well this has been fine. having the gibs any tighter than just closing the gap causes the screw to torgue up before you get motion and it gets worse as the machine warms. so only test backlash with the gibs loose, then use the difference in backlash to tell when you are over-tightening the gibs. as you tighten the gib recheck the backlash, when you see the backlash increase back the gib off a small amount until is goes back to what it was and lock it down.
    if you use the thrust bearing mounts like I used the nut has 2 set screws to lock it to the shaft, make sure they are tight, they loosened on me once. I was afraid to tighten them too much because they are screwing against the threads. so to get the preload on the thrust bearing correct I unbolted the bearing block from the mill so it was free to spin just on the screw. I adjusted it until a small amount of binding is felt and then backed off just until I had smooth rotation plus a very little bit for temp change but no wobble.. at that point I locked the set screws down really tight. there is no need to ever readjust these bearings unless they wear and if they are worn they are bad.
    another thing I just remembered was I didn't try to get any of these setting right until I had quite a few hours of running on the machine and a good break in. I wrote a g-code to move all 3 axis their max distances and just let the mill run for hours oiling every so often.
    I hope that helps
    steve
     
  30. jumps4

    jumps4 Global Moderator Staff Member Active Member

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    we tried to use those couplings on a bf20 build we did at my house with poor results. the rubber center is to squishy lol
    and I had a problem with torgue flex on my lathe build until I installed these couplers (the same style as on my zx45 )
    steve

    $(KGrHqV,!lcFHC18VP)!BR2mNslKGw~~60_3.jpg
     

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