Z Axis Won't Go Below "Zero"

[groswald]

I hope someone can help before I tear what is left of my hair out!

My machine (a Momus) has been working pretty well, then it started having a bizarre problem last night. The Z axis will not drop below zero when running a cut program. Let me explain a bit.

I set up a cut and zero the Z axis to the top surface of the material as usual. I set X and Y to the proper zero locations as well. Then I start the cut. X and Y motion is normal. Z does not move below Zero, even though the Mach3 DRO says it has. Z retract and return motions are normal, except that they stop at zero on the return.

Here's my config and what I have tried.

Mach3 on dedicated PC. No other software running. Gecko G540. CNCRouterParts NEMA23 steppers and cables and the short header cables with current set resistors on the G540 end. 48 volt switching power supply. Mach3 is running the "blue" screen set and erniebro's probe updates.

• The cut program is fine. It had worked earlier in the evening. I did not change it.
  
• I pulled the spindle and disconnected the lead screw. Motion is smooth and easy throughout the range.
  
• Realigned the lead screw attachement. There is no binding. I can turn it with fairly light finger pressure throughout the range.
  
• Reattached the spindle and verified motion is still unobstructed.
  
• Set Z velocity and acceleration to very low values. No change.
  
• Jog motion is unaffected. I can jog the Z up and down to any point in its range with no issue.
  
• Zero height set is unaffected. I can set the Z height using the automatic setter to any height.
  
• I did not set soft limits, at least not on purpose.

I do not believe the problem is mechanical. My next step, unless someone can help, is to wipe out Mach3 and do a clean reinstall and setup.

Any help is appreciated!

Thanks,

Randy


Any and all ideas are appreciated.

[ger21]

If the DRO says it should be below zero, then it should be. My guess is a corrupt .xml. You could try restoring a backup .xml file. Look in \Mach3\xmlbackups

You'll need to rename the file to .xml

If that doesn't do it, then either create a new .xml from scratch, or reinstall.

Once set up, make a backup copy of your .xml and keep it in case of problems.

[groswald]

Thanks Gerry. I'll give it a try. I don't have a backup, but I do have a clean copy of the G540 xml file. I'll start with that and do a re-setup from there.

Regards,

Randy

[fizzissist]

What are your Z, or H offset values?

If your Z zero is set at the max travel given your Z offset, it could go to what is your programmed Z0 that happens to match the max travel given your Z offset. I had that happen once...drove me nuts. I'd reset stuff, and forgotten to check my offsets.

[groswald]

Well, the problem has gone away. I still have no idea what caused it. It is now working fine. I'll have to wait for future recurrences to to additional diagnostics.

Thanks for your thoughts ans help.

Regards,

Randy