Need some help on stepper

Hi,

I have a strange issue with my z stepper (not moving under certain condition). I'm currently calibrating my axis using pronterface with sprinter firmware. I calibrated x and y and changed their axis_step_per_unit values without any issues, but when I do the same for z, it just doesn't work. The original axis_step_per_unit value for z is like 3200/1.25, with this value, z moves fine in both directions, but that only gives me about 50% of the distance that I instructed it to move, so I did some calculation and changed the value to about 4980, once I did that and recompiled/reload the firmware, z would not move, it just gives a loud noise in either directions. What am I doing wrong? I've tried changing the wiper on the z driver after reading some posts here, but that didn't do anything. As soon as I lower the value to less than 4100, the motor would work again, so I can't calibrate my z. Any suggestions?

Edited 1 time(s). Last edit at 03/26/2012 09:51AM by scanboy.

Try to move the axis slower in your host software, as you are telling it to do more steps in the same time you might have reached a speed limit.

Try to reduce acceleration (in firmware).

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Most of my technical comments should be correct, but is THIS one ?
Anyway, as a rule of thumb, always double check what people write.

When I look in the firmware, there's max_acceleration and a max_travel_acceleration, which one should I lower? or do I need to lower both? Thanks.

ok, it works if I set the acceleration to 0, anything > 0 will give me the same issue, but setting it to 0 is extremely slow, takes forever to go 10mm. Can't I make it go further without increase in speed? I mean I had no issues when acceleration is 50 and unit value = 3200/1.25, I just need it to go further without accelerating. Can it be done? Help.

Have you checked your Z-axis stepper driver current? Could it be turned down too low?

I have it set to 0.32V @ the driver, I don't know what the current is, I can measure it tonight. My stepper only takes 0.6a max, but I've tried other lower voltage also, same issue. The thing is, even at 0.22V (my initial driver setting) it would work if steps/per unit is lower than 4100. I don't know what's wrong, maybe my stepper is not up to par.