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Machine design-determining ball screw speed

Discussion in 'CNC Mills/Routers' started by Dave Dreher, Apr 14, 2020.

  1. Dave Dreher

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    Hello

    I started compiling parts for my linear rail, workbee upgrade. Kept sourcing and now just going to build a new machine

    quick summary is using the C-beam for pretty much everything, Y is going to be doubled C’s and using 1/2 alum for side plates. Using 15mm linear rails. Modeling after the avid. Y is 1500mm X is 1200mm. I know I’ll loose some rigidity but for my space being able to “front load” is pretty huge.

    Ballscrews. Went with 1605’s. I know there is a lot out there about the 1610. So issue is figuring out my speed. Anyone have the calculation? Can’t seem to source it

    do want to drive this with the high torque steppers and black box from open builds. No electrician. In my comfort zone

    build major parts in fusion. Will post after a bit. Just wondering if I screwed up with the 1605? Like to hit rapids of 200ipm.
     
    #1 Dave Dreher, Apr 14, 2020
    Last edited: Apr 15, 2020
  2. Giarc

    Giarc OpenBuilds Team
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    The 1605 has a 5 mm pitch so I believe it moves 5 mm/ turn. If I am correct that is 5.08 turns per inch. so your steppers would have to turn 1016 times for 200 inches. So 1016 rpms to get you to 200 ipm. Check my math to be sure. You will have to look at the stepper spec sheet for the rest.
     
  3. Rob Taylor

    Rob Taylor Master
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    Decent rapids with 1605s likely require servos. I have a fairly similar plan for a future machine, planning on 1610s. 1500mm is just too far for a 5mm pitch screw.
     
  4. Dave Dreher

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    Dang, should have done more research. Is what it is, bearing blocks will be the same. So most likely keep the 1605's in the build, can swap out at a later date. Once it's up and running can re-access. Work has been busy, hoping to get this going in the next few weeks. Build is pretty simple, but still a fair amount of fabrication. Thanks
     
  5. Rob Taylor

    Rob Taylor Master
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    You should still be able to get 100-140IPM still, I do on my (dovetail way) mill without issue. It'll seem pretty slow on the much larger machine though. The 400-800IPM range feels more reasonable on extrusion machines.

    Acceleration is a big deal too. That depends on your motors and drivers though.
     
  6. Dave Dreher

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    So since we are on open builds. What if we through in the black box and their high torque steppers??

    I’m doing what I should have done from the beginning. Little more research. But I’ll admit when it comes to electronics I’m out of my comfort zone.

    What speeds could I push with this setup? Sorry for what I’m sure is a dumb question.
     
  7. Dave Dreher

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    Pic of the gantry in process. Workbee cut the mounting holes. But not trying to profile with it. Setting square off plate sides. Might not be the best way to do it. But what I got.

    was thinking of alternate C configurations. But landed on this one. So I can run screw in between them. Will add stiffner plates etc. guessing gantry will weight about 50-60 pounds. Full 1500mm length

    A7AF01A5-FEF1-4C40-B110-D37FEEFE8B1A.jpeg
     
  8. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Speeds depend on pitch of the drive system a lot too, but typically with our leadscrews you should get 4000mm/min rapids, could go higher if you tune the acceleration a little better than than the default profiles. On a GT2 belted machine, 7-10000mm/min should be possible
    Note those all relate to rapids, actual cutting will be limitedby chipload and deflection rather than the drive system
    High Torque motors always make for a nice upgrade, go for it
     

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