Hi here is what is going on. I had to reinstall my OS(XP). I reinstalled Mach3 version 3.043.062. Setup everything. Loaded a gcode file and I noticed my z axis Dro was off. I verified this by measuring the movement and comparing it to the dro reading. I moved ~ 1 inch(measured) and the dro reading was .045. I checked the settings in mortor tuning and everything was correct. I closed the file and restarted Mach3. I retested and measured and it was spot on. I reloaded the Gcode file and it was off my a mile. anyone have any idea what could cause this?

Thanks
Charlie

Check your Gcode file.

Just as an example it could be scaling the Z axis or perhaps changing the coordinate system, offsets, etc.

Tweakie.

Make sure your Native Units match the units you set up your machine to.
This can happen when Native Units is set to mm's, but you setup your machine with inch parameters.
Mach3 defaults to mm's as the Native Units.

Thanks for the relies. I think Gerry Guessed it. I changed the native units from mm to inch and it seems ok now. I must have missed that setting.