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  1. #1
    Join Date
    Jul 2021
    Posts
    36

    CNC720 & Clearpath DC Servos

    I have a problem setting up my machine with a CNC720 controller & breakout board and Clearpath DC servos. I think I may be the only person on Planet Earth that has such a combination!

    First, I have to completely ignore EdingCNC's wiring suggestion for stepper drivers @1:24:

    https://youtu.be/yDuDcJtSGcU?si=RPa1fHkn9kFyWl_D&t=84

    After trying the equivalent of this out of desperation - knowing it was wrong - thankfully there was no damage. It just didn't work at all!

    The way I have it set up now: CNC720 BoB input > Clearpath input

    Step1 > B+(Step)
    Direction1 > A+(Direction)
    Enable1 > Enable+
    Ground > (B-,A- & Enable- tied together)

    Clearpath HLFB+ & HLFB- are not used. CNC720 Breakout Board +5v & DriveAlarm are not used.

    With this, and setting the axes to the correct inputs, I can jog the machine very slowly, but since this is technically before homing it is VERY SLOW. The problem is I can do LITERALLY NOTHING ELSE. Homing does not move the motors! It concerns me that I am allowed to jog the axes beyond when the inductive homing sensors trip, because once I solve the issue of why it won't move when I try to home the machine, it won't stop!

    I simply do not know what to do next. The manual is not written from the perspective of someone being stuck on step 1.

    What do I do next?

  2. #2
    Join Date
    Jul 2021
    Posts
    36

    Re: CNC720 & Clearpath DC Servos

    UPDATE:

    I can now confirm that my wiring is correct. Feel free to refer to this in the future; if you're using Teknic's blue-jacketed 8-conductor cables with Molex connectors, connect them the following way:

    Blue (Enable +) > En1
    White ("A" Direction +) > Di1
    Black ("B" Step +) > St1

    Orange (Enable -) > Gnd
    Brown ("A" Direction -) > Gnd
    Yellow ("B" Step -) > Gnd

    Green (HLFB +) > UNUSED
    Red (HLFB -) > UNUSED

    Yellow, orange & brown can be tied together and should be connected to GND on the CNC720 Breakout Board. The red & green HLFB wires are electrically isolated and it should be okay to solder them to each other and cover with heat shrink. If you could fit all of this inside a connector, then you would only need a four-pin connector to do the job for each axis.

  3. #3
    Join Date
    Jul 2021
    Posts
    36

    Re: CNC720 & Clearpath DC Servos

    UPDATE:

    The EdingCNC manual is not written well, and the website is a mess. Currently, there is no coherent CNC720 manual available as a download, as they are converting to a fully online manual and it is a half-done effort at this point. Technical support is non-existent - keep that in mind when you are choosing a CNC controller. EdingCNC was eager to send me a free unit for evaluation in 2021, and I accepted it assuming that my machine was okay but that's when I discovered that Avid doesn't belong in the Benchtop CNC machine business. Considering the sunken cost, I have accepted my fate that this is the machine I have, but it took a long time and a lot of replacement parts to get to the point where I can wire a CNC controller to it and move the axes. So here we are.

  4. #4
    Join Date
    Jul 2021
    Posts
    36

    Re: CNC720 & Clearpath DC Servos

    UPDATE:

    OOTB, CNC4 & CNC5 are NOT set up for homing at all. I will be talking about CNC5 here.

    The reason I could jog before homing - but very slowly, was because Maximum Velocity was very low (25mm/s). The reason nothing happened when I clicked "Home All" was because Homing Velocity was "Manual", which means OFF. Weirdly, there doesn't seem to be a way to type "Manual" again after changing this value to a figure, so they could have just as easily used a different word like "Disabled", an "off" checkbox or something that more clearly communicates what it means.

    Similarly, "Precise/safe homing velocity" is set to "10% of Homing..." and the rest is cut off; once a number is entered, only a number can ever be entered in this field. I still have not figured out what this even is.

    I could move past the inductive homing sensors tripping because the default soft limits were large numbers (-300mm/+300mm). Assuming home is 0 (it is by default), then this would put it in the center of a 600mm envelope, which is absurd. This is simply a nutty default OOTB arrangement. It is probably responsible for several hard crashes on first startup.

    I have the "Enhanced" Clearpath SDSK motors, which have 6400 "steps" per revolution (I was not in the Artillery, but I recognize this number LOL). I have 10mm pitch ballscrews, which means one full revolution is 10mm. This means that 640 steps, or 1/10th of a revolution, is 1mm. So each "step" is 1.5625 µm, or 0.0015625mm. If you use inches, you probably don't have the internet because it hasn't been invented yet, so you're not reading this anyway. I changed my "Steps per unit" to 640.

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