Me (Toby) and Steve did a bit more work on the CNC. First off we hit some problems setting the feed rate as you now have to do this with grbl 0.9, I believe we got round this by sending the command: G01 F100

After that we tried to move the Y axis. Oddly one of the Y motors was clicking and trying turn as soon as the Arduino was powered up. Even without GrblController connected. After some experimenting we found out that removing the jumpers that mirror the Y driver to the A driver stopped the clicking. Maybe it was coincidence.

So I pulled all of the end stops and disconnected the X & Z motors. I also un-hooked the Y axis drive belts. So all we had connected was the two Y motors, plugged in the same way round. I thought we could sort out the directions with jumpers on the board. When jogging the Y axis the nearside motor (motor A) span ok but a bit granchy but far side motor (motor B) wouldn’t spin and carried on clicking about.

So I swapped the driver chips over so Y chip was driving motor B and A chip driving motor A. I expected that motor B would work and A would click but we still had the same out come, motor A working and motor B clicking. Suspect drivers and CNC board are fine but motor B isn’t.

To prove this I pulled the A motor into Y driver and the X motor to the A driver. This moved both motors as expected. Clearly proving something is blown on the B Y motor. This makes some sense as previously we blew the fuse on the last CNC shield. I had expected something to fail, but suspected a chip not the motor.

I have a spare motor as I originally bought a set of five for a 3d printer so we can swap that out. I also replaced the microstep jumpers and it ran loads smoother.

I also have a full set of drv8825 high current stepper drivers and a 24V 10 amp PSU which we should be using. however we need to make sure the chips are sufficiently cooled as they were roasting.

Posted in Projects on Oct 21, 2015


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