HELP!!    I am at a loss as to why this g-code generates errors in Mach 3.  I use the BobCAD-Cam program to generate my G-Code.  This combo has worked well for years.  Yesterday Mach3 didn't like this code and started throwing errors. I've tried running it through other G-Code troubleshooters and none found any problems. I'm hoping the Mach community can find the problem.

In Config. / General Config.    Change your IJ Mode to Inc.

Ideally all Gcode files containing arcs should contain G90.1 or G91.1 (as approprate). Yours should contain G91.1

Tweakie.

BRILLIANT!!!  The IJ mode fixed it.  I'm not sure which program got changed, but it's working not.  Thanks for the help Tweakie!

I am pleased you got it sorted. 

All of the CAD/CAM software I have uses Absolute mode for creating arcs but BobCad is different and uses Incremental mode. As the IJ setting within Mach3 is modal (it retains the last used setting) it is for this reason that it is good practice to (if necessary) modify the CAD/Cam post processor used to incorporate the G90.1 or G91.1 (as appropriate). Then the problem will not occur again in the future.

Tweakie.

I set my BobCad to post in absolute and saved a .nc file.    Mach3 didn't seem to have any problem reading the file and generating a path.    I'll know what to check next time I make a cut.   Thanks again for all your help.