Looking at the positional data the MC converted correctly when the G21 loaded , BUT the user Coord X0 Y0 did not reset back to X0 Y0 (;-) SO now if you push start the machine will go somewhere it should not go.
![Huh ???](https://www.machsupport.com/forum/Smileys/default/huh.gif)
![Huh ???](https://www.machsupport.com/forum/Smileys/default/huh.gif)
? AND it still does not explain how the machine ended up 4.5 inches off the original coord base
QUOTE:
Operation:
When I center spindle over shaft: MC x=17.9441, y=6.6080. Zero user coordinates, x=0 y=0
Load code: MC x=455.7804, y=167.8425 User coordinates x=437.8363, y=161.2346. This change occurred without running the code.
If Mach 3 is shut down and restarted the shaft zero is again x=17.9441 and y=6.6080.
Just a thought, (;-) TP