Z axis issues when homing for ATC

[psus87]

Hi everyone,
I’ve recently purchased a Supermax Rebel1 and I’m having issues homing the machine. I would like to preface, when I was moving the machine into my shop I did have to manually turn the z axis servo by hand to lower the spindle so the machine would clear the door. The ATC works if I manually set the Z axis height to where it triggers the limit switch for tool change height. The issue I am having now is when I send G28 Z0.0 in MDI the machine will send the Z axis to machine zero in the control but physically it stops a little bit short of triggering that limit to allow for a tool change. Is there a parameter I will need to adjust or am I doing something wrong?

Also while trying to perform zero return on the X Axis and it ended up over travelling and tripping the limit for that. Is there any other way for me to back it off that limit other than manually turning the servo to back it off?

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[the_gentlegiant]

Are you Zero Returning the machine each time you turn it on? If you don't have batteries backing up your servo position, you have incremental encoders that need to be homed after every power on. You don't mention any alarms so that's good.

Try turning on the machine control while holding in P and CANCEL. DO NOT HOLD ANY OTHER KEYS! Hold in P and CANCEL until the control comes up. Then Zero Return the machine in the normal manner. Likely by hitting the +X +Y and +Z keys with the Mode Switch is in ZERO RETURN. To play it safe, have your Rapid Over-ride set in the middle somewhere. Also make sure all axis are at least a few inches away from he home position before Zero Returning. In fact you should always leave a machine like this with the axis away from home when you shut it down.

This will likely fix your problem. Let us know if it doesn't.

[PNaedele]

Are you Zero Returning the machine each time you turn it on? If you don't have batteries backing up your servo position, you have incremental encoders that need to be homed after every power on. You don't mention any alarms so that's good.

Try turning on the machine control while holding in P and CANCEL. DO NOT HOLD ANY OTHER KEYS! Hold in P and CANCEL until the control comes up. Then Zero Return the machine in the normal manner. Likely by hitting the +X +Y and +Z keys with the Mode Switch is in ZERO RETURN. To play it safe, have your Rapid Over-ride set in the middle somewhere. Also make sure all axis are at least a few inches away from he home position before Zero Returning. In fact you should always leave a machine like this with the axis away from home when you shut it down.

This will likely fix your problem. Let us know if it doesn't.

I agree with this. I had a machine with incremental encoders and home position was set by switches and dogs that had a home a couple inches off after I rotated the ballscrew by hand. I forget what parameters set it, but despite being incremental encoders and reference dog, it retained it's position after power off and ZRN moved the machine back to where it remembered zero was. The problem was that it assumes the ballscrews don't move during the time powered off.

I resolved it just like the_gentlegiant outlined.