Need some help troubleshooting a problem with motors jumping position

[jayty97]

I am running a home built 3 axis cnc router with a moving gantry setup. I am using the hobby cnc pro kit with 305 in/oz motors run from an intel mini itx motherboard through the parallel port. I am controlling it with mach 3. Everything works great other that the fact that every so often the y axis (i think its only the y... but not 100% sure) is jumping position by up to 1/2" in either direction, which is rendering the machine useless for anything more than a simple cut. Any Ideas where this may be coming from? The machine moves freely, so it is not a binding or mechanical issue. I've installed a decent amount of cooling, not only on the breakout board, but also on the motors themselves and everything seems to be running nice and cool. I'm stumped as it is totally random and I'm unable to repeat the error at the same place. I want to put up some pics and maybe a vid of it running, but need to work this problem out first... Anyone have any ideas?

[ger21]

Run the mach3 drivertest, drivertest.exe, and see if you get a flat line on the display. It's in the mach3 folder.

[jayty97]

Originally Posted by ger21 Run the mach3 drivertest, drivertest.exe, and see if you get a flat line on the display. It's in the mach3 folder.

Hi Gerry,

Everything looks fine using the test and it completes no problem. I did'nt see any extended flat lines... or anything that stood out...

[finishlinewrx]

What version of mach3 are you running? I had problem with missed steps and backlash comp on a older version.