Does anyone have an idea why during a machining cycle my z-axis is making small movements (maybe a turn on the motor axis) during the first few x-y movements of the program. As far as I can tell (I'm a complete newbie) there are no rogue z commands in my file. I posted it for anyone who cares to comment. File was generated from an Adobe Illustrator DXF.

I just checked out my machine. It seems that while the z-axis is supposed to be on hold at a given height, there's a pulse about every 8-10 seconds which causes the motor pully to jog about 1/4 turn. Result is a constant downward progression in steps of between .003" and .005" every few seconds.

What's up with that? Causes what should be a flat machined surface to bcome progressively deeper during the cycle.

Update - I discovered that having another program running while Mach3 was controlling my machine caused small signals to be sent through the printer port causing the incremental z-axis movements. Problem solved and machine runs fine!

Could you please tell me what program you were running? I try to keep a list in my head of "problem software"