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

[fasteddy]

Hi John S..

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, vaguely remember doing this way back when..

Just fed in the code f25 z100 and it moved the z axis fine, for about 30 secs, then started juddering, faster and faster until it was juddering all the time.. Did the same with the y axis, and this took about 45 secs to start juddering.. Both the z and y are running off the system 3 board drivers and the 24v power supply, which is being fed through the board.. 2.30am now so starting to see double.. Will start some more hair pulling in the morning...

Steve...

[fasteddy]

Morning Jonathan..!

Tried all kernal speeds from 25KHz to 60Khz, makes no difference...

Seems my PC is a dual processor, 2 x 3GHz P4... Have it set for standard PC and have done all the optimizations recommended for Mach3.. Really is a bare bones machine and runs very fast, boots in 11 secs... Even running complex code the processors never get to more than 4% usage... Everything disabled that is of no use, using a pci graphics card (not onboard one which seems to be an issue on some machines)..
Re-checked all my cables and drivers/board (which are very cool due to a pair of fans mounted above them)..
Just swapped round a motor (had 2 spare 3Nm) and made no difference..

Am at a loss now.. No hair left to pull out and no idea what to try next...

Steve..

[Jonathan]

I'd leave it on the lowest kernel frequency as that is inherently the most stable.

Maybe the fans are causing interference in the step/dir inputs ... seems unlikely but you never know. Shielded cable might be the answer, but I reckon there must be more to it.

Try EMC? If that works you know the computer is ok.

Have you definitely wired the optocouplers the right way round on the driver?

(Would type more but I'm going out for the day, now ... hence why I'm up early! Hmm, 800th post.)