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View Poll Results: Belt or screw drive?

Voters
106. You may not vote on this poll
  • Belt drive

    30 28.30%
  • Screw Drive

    76 71.70%
Page 2 of 2 12
Results 21 to 29 of 29
  1. #21
    Member
    Join Date
    May 2011
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    790

    Re: belts vs screws?

    Did everyone else just skip over the 5 or 6 axis part and go straight to the belt vs screw discussion?

    From what I've seen, the OP didn't say leadscrew or ballscrew. He just said screw.

    Also, there has been no mention from the OP about dimensions of the machine. IMO, an important detail to leave out.

    No vote for rack and pinion? Depends on machine size, IMO.

    I'll vote for the ballscrew. Belts, perhaps the least expensive, perhaps they have a place for hobby machines on a budget, I'm not going to slam that too much. But on a 5 or 6 axis CNC machine? No, they don't belong there.

    Perhaps the OP can give more info.

  2. #22
    Member
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    May 2011
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    790

    Re: belts vs screws?

    Wow. Old thread. How did this find it's way into "Today's Posts?"

  3. #23
    Community Moderator ger21's Avatar
    Join Date
    Mar 2003
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    35470

    Re: belts vs screws?

    It's a poll. Any new votes bump it to the top.
    Gerry

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  4. #24
    Registered
    Join Date
    Mar 2018
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    1

    Re: belts vs screws?

    Hi there, I wonder how compares in precision the different solutions : Belt vs Ball Screw vc Lead Screw vs Rack & Pinion vs Chain ?

  5. #25
    Gold Member
    Join Date
    May 2005
    Posts
    3920

    Re: belts vs screws?

    Quote Originally Posted by lalebarde View Post
    Hi there, I wonder how compares in precision the different solutions : Belt vs Ball Screw vc Lead Screw vs Rack & Pinion vs Chain ?
    The comments below are largely opinion based on years doing automation maintenance and may not reflect the experiences of others.

    1. Don't even consider chain drives! They are a maintenance night mare.
    2. When it comes to ball screws vs Trapezoidal lead screws ball screws are generally the better choice. However lead screws are likely more reliable in hostile environments. Lead screws and ball screws are the common solution for precision machine movements.
    3. Rack and pinion is a good solution for very long axis. It has its own unique maintenance issues. The biggest problem with rack and pinion is backlash management. Precision can be good but may require the use of servos and gear boxes which end up being hidden expenses.
    4. Belts (I'm assuming timing belts here) are very good with respect to precision but do suffer from belt related issues such as vibration in the belt and often a lack of stiffness. Sadly almost every router implementation of a belt drive solution I've seen has used a belt that is way too narrow and probably of a lighter series than would be ideal. Even on pick and place machines they regularly use belts 50mm wide, sometimes wider, for major axis motion.


    Speaking of precision, often what you really want out of a CNC machine is solid repeatability. That is the first part comes out exactly like the last part. MOST low end routers are not precision machinery like you might expect form a milling machine. This is due to light frame construction, stepper drives in open loop designs, rolled lead screws (often the cheapest) that simply are not that accurate and a number of other factors. Of course in the opposite direction, where money isn't a problem, routers can be built that are nearly the equivalent of a bridge mill. Generally this forum focuses on lower end DIY machines with precision expectations in line with that.

  6. #26

    Join Date
    Jun 2021
    Posts
    10

    Re: belts vs screws?

    I want to add a vote for chains.

    Why:
    - Chains are the only real cost effective option for high precision at larger sizes.
    - Leadscrews just too costly at 8'
    - Belts are hard to get precision at 8', by which I mean 1mm, due to the issues mentioned of vibration, slack and slip.
    - Rack and pinion (ie. linear tooth rails) are the industrial soln for this, but also very costly at 8'. 8ft gear rack = $300. 8ft #35 chain = $15
    - The maintenance of chains is low IF the system is well designed, by which I mean proper chain size, pathway and tensioning.

    Really the best drive depends a lot on size, cost and precision goals.

  7. #27
    Registered
    Join Date
    Jan 2008
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    1264

    Re: belts vs screws?

    Show us a decent machine that uses chains
    7xCNC.com - CNC info for the minilathe (7x10, 7x12, 7x14, 7x16)

  8. #28

    Join Date
    Jun 2021
    Posts
    10

    Re: belts vs screws?

    https://youtu.be/pNVwrx3W-5o

    This is from 2015.

    My latest machine has 1mm accuracy on XY axes, chain driven. Rebuilding Z now.

  9. #29

    Join Date
    Jun 2021
    Posts
    10
    PS. I should have joined cnczone years ago. Making up for lost time I guess. In general I'm too busy to post much so I'll likely disappear for another 10 years until my next machine.. lol. When I started it wasn't even possible to find cheap, high current stepper drivers on-a-chip. Would have been a lot easier for me if I had found this community earlier.

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