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Nema 17 mount interference?

Discussion in 'OpenBuilds Forum Help' started by Afcj1993, Oct 18, 2020.

  1. Afcj1993

    Afcj1993 New
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    Hi, I have a nema 17 attached to a mount running off of an arduino uno using a tb6600 stepper driver. The motor will operate just fine up to around 2400mm/m right up until I slide the t nuts of the mount into the aluminum extrusion frame, then I cant go above 500mm/m. I found that the motor is then conductive with the the frame, so I tried to ground the frame and that didnt work, however if I leave the mounting nuts loose the poor speed issue is spotty like it is dependent on the nuts being tight. I tried removing the nuts and just holding the motor attached to the mount up against and all around the frame with no issues. Tried different motor and driver. Only other thing I can think of is nylon screws and nuts. If anyone can give some advice it would be greatly appreciated.
     
  2. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    Sounds like a defective stepper. The coils should be fully insulated from the frame.
     
  3. Afcj1993

    Afcj1993 New
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    I dont believe so but maybe. I'm electronically inclined but not so versed though. The motors I'm using were from a sainsmart 3018 cnc and they worked fine on that machine and I've tried 2 of the 3 motors and they only have the issue when on the new frame, that said, the sainsmart machine motors weren't connected to aluminum extrusion on the 3018 instead it used thick plastic plates and had extrusion only as structural support. Also I'm sure of the wiring step setting and set the current via sainsmart website and actually bumped it up from 1.3 to 1.5 and had no issues until now.. should've finished college lol
     
  4. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    Actually this is tech school stuff. And I won’t claim to be an expert on all things motors but generally current coming through the motor housing is a bad sign. It means a coil is blown and is grounding to the frame. If you have a multimeter I would suggest Ohming all the coils and also testing each wire against the frame.

    Is there any chance tightening the screws is distorting the housing? Also are these common 4 wire bipolar steppers?
     
  5. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Just motor, or belts, leadscrew, etc attached? Pics or video of what you have going on may help us spot something but agreed, unlikely the motor itself. Probably more mechanical.
     
  6. Afcj1993

    Afcj1993 New
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    I may have wrote that wrong. The motor and frame are conductive which I didnt quite think about metal on metal duh. Makes sense now.. that said I checked and there is no current running out and into the frame itself as far as impedance it seemed to very from frame to motor screw by moving that axis from 40ish to 5ish then stayed on the lower side. Thanks for the assistance.
     
  7. Afcj1993

    Afcj1993 New
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    Ended up having to trim the video into 2. The only difference is mounting the motor, both moving 5mm at 1000mm/m two times and the mounted version stutters, it is a 4 wire bi polar running at 800 steps per rotation I believe. Also the frame is pretty much mocked up I just need to get the electrical working and then attach the belts which I've already cut to length and adjust the laser.
     

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