Stuttering stepper motors

Hello RepRap forum,

We have just completed our first 3D printer build, and everything is working perfectly, except for one thing:
After a certain amount of time, most of the times after homing either axes 2-3 times, the NEMA 17 stepper motors stop making fluent motions, and instead start to stutter. What I mean by that, is that, if you tell them to move one of the axes 100mm for example, they do this in four steps of 25mm, and keep stopping 0.2-0.3 seconds inbetween.
However, after the axes have reached their destination, you can still hear the stutter inside the stepper motors.
We have already rechecked all of the wiring and our USB2.0 cable is brand new.

We would like to ask you all for your help, because we seem to be totally stuck at the moment
Kind regards,
Tim, Teun and Lotte

If your stepper drivers are overheating, they can cause a stutter. You may want to reduce the current/vref. Check them per something like [reprap.org]

Thanks for the quick answer, how does one do these things exactly?

-T, T and L

Instead of reducing the current you could also place a cooling fan on the stepper drivers. They will provide airflow that allows the stepper drivers' cooling elements to transfer their heat to the air.

Groetjes!

Thanks! We will try to use a fan, and if that fails we'll look up a way to tone down the current a bit
Again, thanks for your help!

-T, T & L

Edited 1 time(s). Last edit at 01/29/2014 06:17AM by TimTeunAndLotte.

Quote
TimTeunAndLotte
Thanks for the quick answer, how does one do these things exactly?

-T, T and L

Exactly how you do it depends on the stepper driver. The link at [reprap.org] has a picture with someone measuring the reference voltage Vref off the wiper of the adjustment potentiometer. The official guide for Pololu shown in the picture is at [www.pololu.com] under the "Current limiting" section. If you haven't tuned/adjusted/measured the current is your drivers, they could be set anywhere.

If your stepper drivers are not getting hot enough to trigger the over-temperature protection, then it might be another issue.

In any case, it would be good to at least measure the Vref and calculate the current your drivers are attempting to pass through.

Quote
Ohmarinus
Instead of reducing the current you could also place a cooling fan on the stepper drivers. They will provide airflow that allows the stepper drivers' cooling elements to transfer their heat to the air.

Groetjes!

It's important to first set the Vref correctly to make sure that the current is not too high for the motor or the Pololu. Putting a cooling fan is secondary.