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Going vertical

Discussion in 'General Talk' started by Jonathan Warawa, Jun 29, 2018.

  1. Jonathan Warawa

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    I am hoping to build my first CNC, and am thrilled at the possibilities after watching a few videos. I can't help but notice that most builds focus on framing a horizontal XY frame with very little vertical Z dimension. Any of the builds I see that use some vertical control use a drive screw system. I am wondering if this is absolutely necessary, or only used in the cases of heavy tool attachments that need leverage, such as the plunge force of a router.

    I ask because I am hoping to build a vertical XY frame for a CNC that moves around a small scanning device that weighs only 0.5 lb. I looked at the Acro system and wondered what would happen if it were turned upright so that the sliding arm stood vertical. My question is what would happen to the belt system and the motor's ability to hold my 0.5 lb scanner at a set height without drifting due to gravity. I ask because I can't help but notice that screw leads have a max length of about a meter, which kind of limits how tall my build could go. A belt driven vertical lift opens up taller possibilities.

    As I'm typing this, I now wonder whether setting the Acro system on end with the arm horizontal and the side rails vertical would then provide two motors holding the weight of the sliding arm and scanner upright, and perhaps two motors would allow for better weight support than just the one...

    Thank you in advance for the help!
     
    #1 Jonathan Warawa, Jun 29, 2018
    Last edited: Jun 29, 2018
  2. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    A half pound would not likely be an issue on a vertical belted system. If you keep the top pulley small, say an inch or less, half the width would be 0.5" times maybe 12 oz. for the load and gantry plate weight that'll require 6 oz.-in. of holding torque and a decent Nema 17 stepper can handle 12 times that much. Holding torque is only available while the power is engaged though so the load may glide down during a power interruption but this is easily resolved with a small counterweight should there be a problem. The big question here is do you need fast starts/stops or instantaneous reversal of direction? This could have an impact on the size of the stepper and/or the coarseness of the belt.

    If you would like a better idea of what the OpenBuilds linear actuators are capable of, actuator test data can be found here.
     
  3. Jonathan Warawa

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  4. Jonathan Warawa

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    Thank you for the response. I am also wondering how difficult it is for a novice to setup software. I see that the stepper controllers appear to come with a license to download PC software. I have simple 3D path I want to setup on repetition which would be akin to a scanning probe being inserted in to a series of cubby holes. Is the software pretty self-explanatory or is there an online course to help with setting up a simple program?
    Thanks!
     
  5. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    You probably don't need a board that elaborate (or expensive). Google "Arduino stepper motor control" and it'll give you an idea of how simple this is and how minimal the control requirements are. It's fairly likely that someone has already created code for what you need or at least something reasonably close.
     

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