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Taking the Mantis for a jog

November 10, 2011

I hooked up the Mantis 9.1 to my build of the GRBLshield and used GCtrl to jog it around. Very boring video evidence (excuse the bad sound, you don’t need it anyway):

Tonight I opened up the terminal window in Arduino and input new steps/mm settings for the 3/8×12 leadscrews. I haven’t been able to find any info on whether the stepper controller half-steps or not, but I believe it does, so I came out with 188.976 steps/mm. When I hook it up to jog again I can measure the result and see. If it’s wrong I should be off by a factor of 2.

Next up: finish the spindle and work up some kind of decent mounting system for the electronics, including a power plug so that I can unplug it from the PS more easily. There are lots of scrap parts at Splatspace.

Then wrestle with the toolpath for creating Gcode. After confirming that it moves correctly with simple commands, put in a bit to level the bed.

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7 Comments leave one →
  1. November 13, 2011 4:34 pm

    The grblshield runs 1/8 microstepping by default unless you change some resistors on it. So the one you got is set to 1/8 microstepping unless you messed with it (I know, I built it for you). So if I read your post correctly the lead screws are 12 threads per inch. That’s (1/12)*25.4 or 2.116666 mm per revolution. If you motors are 1.8 degrees then that’s 200 steps per revolution, or 1600 steps at 1/8 microstepping. divide this by 2.11…. and you get 755.9055 steps per mm. Or 4 times what you got when you thought it was 1/2 stepping. SO your math is correct and only the parameters need to change.

    BTW you can change the stepping by playin with resistors r16 – r19. A schematic can be found here:
    https://github.com/synthetos/grblShield/blob/master/hardware/grblshield_v1_schematic/grblshield_v1_schematic_pg1.pdf

    Let us know how it works!

  2. Alden Hart permalink
    November 13, 2011 8:53 pm

    I’m not sure what’s going on. I did this math for my setup and it works for that config (Zen Toolworks). You could verify that the grblshield is running 1/8 step by comparing the step setting resistors; but I’d be surprised if it’s not.

    • Alden Hart permalink
      November 13, 2011 8:55 pm

      I didn’t see your second reply. Yes, I’m referring to the commercial grblshield that’s produced by Synthetos. Mystery solved.

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