I replaced my DRV-8825 stepper drivers today A4988 this evening to test the difference in print quality.
With the DRV’s, I can’t ever recall any slipping on any axis. I had the Y axis shifting multiple times with A4988’s. Anyone experienced this before?
Likely wasn’t slipping but rather thermal protection mode kicking in.
Best option: switch to Trinamic 2100’s.
5984 and 6128 are both excellent performers that handle higher currents than 2100s, if you have big motors.
I’ll try adjusting the reference voltage again…
These cheap A4988’s are Chinese clones, with R200 resistors. The drivers are very weak.
I need to set the reference voltage to 2.72V to get 1.7 Amps fed to the Steppers.
The maximum achievable with these drivers it’s 1.6V, meaning I can only ever get to 1A!
I put back the drv8825, but lowered the microstepping to 1/16.
Let’s see if it’s on now.
Busy printing a ‘nose flute’ to test… Lol.
Just for reference, I had measured the Positive on the trimpot itself, and the negative (ground) from the power supply directly. I hope this is the right way to do it…
Ahh, too slow there I see…
I had the reverse problem, I went from perfectly tuned a4988s to overheating motors on the DRVs. turns out the cheap a4988 carriers use different sense resistors from the reference design (0.1Ohm vs 0.05Ohm ref), so all the calcs from the usual sources were out. Also watch out for 32 stepping and 24V on the DVRs, you get some weird effects at low speeds, e.g. extruder.
@bob_smith1 , there is a solution for that http://cabristor.blogspot.com.cy/2015/02/drv8825-missing-steps.html
Yeah, that is the method I used, works a treat when you don’t wire the diodes incorrectly! 