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  1. #1

    Join Date
    Oct 2020
    Posts
    2

    DIY VMC Opinions

    Hey guys,
    What are your thoughts about this build?

    The workspace is 300x250x250mm. I would use 20mm linear guide on all axes (how strong precompression?) and 20mm 5mm pitch (2005) ballscrews with antibacklash nuts on all axes. The plates would be rotary ground steel plates. The Y axis "holder" would be filled with epoxy granite mix. Planning to use ER20 watercooled spindle. The motors are nema 34 servos.
    Do you have a reccomended spindle or different collet type?
    What should I improve on the design?
    What controller should I use?
    I attached the pics.

  2. #2
    Registered
    Join Date
    Dec 2003
    Posts
    751

    Re: DIY VMC Opinions

    It desperately needs some diagonal bracing to prevent the uprights flexing under load.It also seems considerably overpowered with those NEMA 34's,they will just bend it further and faster than a more modest motor.There are some apps out there for Android phones that will calculate the force generated by any motor you specify with the thread you select.I suggest you run the figures and see what kind of force you need to accommodate.If the CAD package you use has a FEA capability,run it to find the weak points with that kind of force applied and then improve it.A couple of tubular steel braces will almost certainly cost less than five or six buckets of epoxy based filler and will take less time to have ready-once it becomes clear where they are needed.

  3. #3
    Registered
    Join Date
    Jan 2008
    Posts
    1131

    Re: DIY VMC Opinions

    Google VMC frames and have a good look at them.

    Look at rail spacing, proportions etc.

    Nothing should be a flat plate.

    To be blunt, your design is going to be very weak. Start again.
    7xCNC.com - CNC info for the minilathe (7x10, 7x12, 7x14, 7x16)

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