I´ve build a pan/tilt-head for a DSLR.
There is only a reduction by the pulleys of 1:4,5 on both axis. And there is no high load, which needs to be moved.
I’am using the DRV8825 stepper drivers and 1209-steppers. (pololu.com/product/1209)
The drivers are controled by a Arduino MEGA. For the tests, I have just put the step-output in an slow ON-OFF-Loop.
Since I need a higher resolution, I want to use at least 1/8-steps.
After setting up everything and running couple tests, I have noticed, that the steps are not running constantly.
In the videos, you can see the unconstant movements. Trying different adjustments of the regulator on the DRV8825, did not improve the behaviour. To get fairly aceptable results, I have to set the regulator so high, that the stepper and the driver are getting hot (which is bad, because it is a portable setup, so I have limited battery-capacity and I don´t want to lose energy by heating up the components.)
I´ve also tested other steppers (0.9° and a little bigger). Same here, it is not possible to get equaly spaced steps.
The cable is about 1,5m long.
What could cause those unequal microsteppings? Would a special stepper or different drivers help?