Help! Steppers losing steps and making a racket under slow feed..

**Jonathan** · 31-07-2011

Are you using the lowest Kernel frecquency, 25kHz? If that isn't sufficient you may need to use 400 step/rev.

I would check the bios ... disable everything you can that's not useful.

Changing the pulse with from 0 to 5us wont make a difference as it defaults to 5us if you put 0 (I think, might be wrong).

Have you ran the driver test program to check the parallel port? If not I'd start with that...

**fasteddy** · 31-07-2011

Running it at 25KHz, driver test ok.. Really strange the way the motors behave at low feed rates, almost a grinding noise from the motors and they stutter like crazy.. As soon as I put the motors in rapid (G0) they seem to 'kick' out of the stuttering and rough noise and run really smooth with no loss of steps..

Have checked and re-checked everything I can think of, mechanically the z and y are slick and move very freely. Can pop a 6mm spanner on the rear shaft of the motors and turn them by hand with no effort so the problem does not seem to be there.. Even when under power at low feed rates, when they are stuttering, I have tried gripping the ball screws to see if I can slow them down, but I cant so does not seem to be a loss of torque (or I am as weak as a soggy digestive) and the motors are running cool.. Have a spare axis on the board (with an on board driver) and have tried swapping the the motors around but get the same result..

Am at a complete loss as to what is happening here..

Any ideas anyone? Or maybe you can lend me a bigger hammer...?

Steve...

**John S** · 31-07-2011

Originally Posted by Jonathan

Changing the pulse with from 0 to 5us wont make a difference as it defaults to 5us if you put 0 (I think, might be wrong).

.

No it should sat at what ever you put in. A low setting can cause problems for some drivers as they don't have time to read the pulse.

Where it affects machines the most is on spindle speed.

What concerns me is the statement "Just checked and only the X axis had the pulse width set to 0, and it was running fine, have set it to 5 now.. z and y were already set at 5"
You cannot have different values for different axis, what is set for one is set across the board - unless the latest version - which we don't use is different, perhaps I need to check.