I'm using a Chinese 6040 with an ethernet smoothstepper and a G540.

I like to manually adjust my z-axis to zero when I start a job and when I change tools.

At present I click the 'Reset' button in Mach3, which stops my G540 holding the steppers, do the adjustment, then click reset again.

This seems like using a sledgehammer to crack a nut -- I just want to free a single axis for a few moments.

Is there any way to do that?

Thanks,
  Tom

You are better doing it within CNC rather than disabling axis/axes. Simple way is just jog down and change to step mode until you are on the surface or can slip a feeler or a slip gauge under the tool, you can then set the DRO zero or set it to whatever the thickness of the gauge is.

Disabling axes is not a good idea, for example your steppers may be on a microstep and when you disable they will jump to the nearest step thus they will be slightly out of position, the more times you do that in a job the more the amount will be.

Lots of people use auto tool set routines where they have an input to Mach connected to a touch plate (can be as simple as some copper clad PCB) they then call the auto tool height routine and the machine will touch off the plate and set the correct value.

Hood

Thanks Hood -- I wasn't aware of that microstep issue. I'll bite the bullet and get a touch plate set up.

Hood doesn't mean that a touch plate is necessary. I believe he is telling you there is no verification of stepper position after a reset and subsequent repowering. With each reset, many steps can be lost. If you do this for every tool change the positional loss could accumulate and make your part out of tolerance.