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BlackBox: Milling 1 mm dia circular pocket

Discussion in 'Controller Boards' started by GS76, Apr 25, 2022.

  1. GS76

    GS76 Well-Known
    Builder

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    A question regarding the OpenBuilds BlackBox as I am considering purchasing it: I am tired of these other CNC control boards with minimal to zero support.

    This question is difficult as there are several variables.

    Assuming I have a "stiff" CNC milling machine (desktop size) with minimal run-out on the spindle and minimal "micro-stepping" of the stepper motors with the required torque. Is there any reason within the electronics of the BlackBox that would prevent it from milling out a 1 mm circular pocket within +/- 0.025 mm concentricity?

    I am just asking this question as the "scale" that I would be milling out this hole is most likely smaller than typical milling work.

    I hope my question makes sense.
     
  2. David the swarfer

    David the swarfer OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

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    Yes, but it depends on your actual machine step size, ie, how far does X/Y move for 1 motor step?
    That has to be <= half of the 0.025mm tolerance otherwise it just cannot get close enough to the positions commanded.

    The blackbox runs GRBL firmware so you can read all about that at GitHub - gnea/grbl: An open source, embedded, high performance g-code-parser and CNC milling controller written in optimized C that will run on a straight Arduino

    The blackbox defaults to 8x microstepping so you can use that in the calculator at
    GRBL settings calculator
    to figure out your step sizes and rates. (Just use the Z cal area if your machine has screws all round, the calculator does X and Y as belts)

    So in short, yes, GRBL can do it.
    Can the mill hardware do it? (-:
    and can you measure the bit accurately enough to get the correct offset in the CAM in the firstplace? since GRBL is 'compensate in computer' only, no tool diam offsets inside GRBL so you have to get it right in the CAM
     
    sharmstr likes this.
  3. GS76

    GS76 Well-Known
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    Thank you for the reply.

    I appreciate the information.

    I will be purchasing the BlackBox. I am excited to get started!
     
    sharmstr and Peter Van Der Walt like this.

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