I think the Amazon pic has the top side and then underside but also turned upsidedown. Looks consistent with mine.
JCA34F what do you mean [quote="JCA34F, post:20, topic:1350231"]
unavoidable detent torque
[/quote] Can you elaborate and can you confirm you are also using a DRV8825?
So I may have a solution with a different HW/SW combo. Check out this guy and his website.
Great find, I am tempted to build one of those designs. The TMC2208 has a reputation for smooth motion, I will try one soon.
First thing I would do is design a PCB for the controller.
Well the TMC2208 was much smoother, quieter, and did not have this cyclical pulse. I used the same code and same 1/16 microstepping as the other driver. So it is the driver that is the main culprit.
I am now troubleshooting the stevesclocks configuration. I have the CNC Shield V4 soldered up and all the components connected. The arduino code is running as indicated in the serial monitor section but the motor is not running. So more trouble shooting to do.