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  1. #1

    Servos, Power and Programming

    So I've been wanting a CNC router for a few years for wood, and occasional light aluminum work. At heart I'm a CNC newbie. I usually get stuck in a recursive loop that involves me wanting to build better than shapeoko, then not wanting to actually build it because I couldn't afford the quality I actually want. I'm a carpenter by trade, and as a result my wants from a CNC are pretty high. Now that I can afford a DIY CNC of good quality, I realized I don't think I actually have the power required to run the size I want. I rent, and I have 20 amps @ 110 in the garage. Turns out day dreaming doesn't take real world requirements into count. I'm pretty sure an additional subpanel would be very expensive, I think the main would need a serious upgrade. I would be willing to get it done right(or wrong), but its probably not worth it on a rental. Though I am questioning how much I really need the A/C from now until June. I happen to have a 7 CFM vacuum pump too, and no one would be the wiser....

    So there goes what I really want until I move. Right now I'm looking at a 32" x 32" x 6" working area. Approximate to be based off of rail and screw sizes. Wood frame, linear rails with ball screws. Makita or dewalt router.

    I was looking at clearpath until someone clued me in that DMM and Delta were out there. I still am because it looks like Delta and DMM would consume too much power for me, even though it might be cheaper. AND I am super interested in using C++ and software to directly control the servos. I have other motion control applications where a software language controlled servo would be amazing because then the knowledge and tools would be universal from the CNC to what I'm building with said CNC.


    What do you guys think? Will clearpath be too much power, and I should just get some 3-4A steppers?

  2. #2
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    Re: Servos, Power and Programming

    Axis servos don't actually use much power.

    E.g. 3x 400w servos - you won't ever actually use 1200w as they will never be all at peak power at the same time.

    For steppers, the rule of thumb is add up all the amps then times by ~2/3rds to get required power supply.

    For a small machine, 200w servos would probably be fine but often cost the same as bigger servos.

    If you are building a wood frame, I dont think the cost of servos is warranted. Closed loop steppers are cheap now.
    7xCNC.com - CNC info for the minilathe (7x10, 7x12, 7x14, 7x16)

  3. #3

    Re: Servos, Power and Programming

    Yeah I think you're correct. After going through the price of everything again, using servos would have made the drive system ~80% of the cost.

    I figure its probably for the best. There is a reason we don't give teenagers keys to the lambo.

    I don't suppose you can suggest some reputable buyers for steppers, rails, and screws? Would McMaster Carr be decent for some of the parts?

  4. #4
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    Re: Servos, Power and Programming

    I am not in the US but I believe McMaster Carr will not be a cheap exercise.

    Virtually everyone doing hobby machines buys from China.

    "BST Automation" on AliExpress (Google it) is reliable based on my personal experience and many reports from others.
    7xCNC.com - CNC info for the minilathe (7x10, 7x12, 7x14, 7x16)

  5. #5
    Community Moderator ger21's Avatar
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    Re: Servos, Power and Programming

    What do you guys think? Will clearpath be too much power, and I should just get some 3-4A steppers?
    Get 400-450oz 6 amp Nema 34 steppers. On such a small machine, you won't see much difference, and you'll save at least $1500.
    Servos won't make a lot of difference until you want to get over 500ipm.

    And you can control steppers just as easily with your own custom motion control software. You just need motion control hardware that allows you to write firmware for it.
    Gerry

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    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

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