I have a vertical milling center, X&Y on the table and Z on the column.  I'm running Mach 4.2 V5036 (very recently upgraded from V4809) and ESS v285.  Bone stock screen set. The part I'm trying to make is a simple knob for a spindle lock I'm working on.

When I load the G-Code the tool paths show oriented correctly in all of the Tool Path windows HOWEVER, when I run the G-Code (Cycle Start) the machine is moving along a tool path that seems mirrored and flipped.  For example I'm expecting the table to move in the X+ direction (as shown in the tool path) but it moves in the X- direction.  Same for the Y Axis.  The Z-Axis is behaving correctly.  Interestingly enough though, when I Jog the axes around (using MDI or just the Jog buttons) they move as expected.

I am new CNC'ing so Im suspect I've set something up incorrectly somewhere.  I've tried two different CAM packages to create my G-Code and both result in the same behavior.

Any help or suggestion will be greatly appreciated.

Remember that tool path motion is showing the motion of the cutter relative to the work piece. For a typical bed mill this will mean that in order for the cutter to move to the right (X+ motion) in the work, the cutter head sits still and the table of the mill will move to the left.

So to correct my error I would "Reverse" the motor direction in the motor setup in Mach?  Is that correct?

Yes, that is the most common way to do it. In order to keep my sanity while dealing with this sort of issue I rely on the on-screen DRO increasing in value to prove that the axis is moving in the + direction as Mach understands it, while confirming that the apparent physical motion of the cutter in the work piece is also moving in the + direction.

Well heck...that didn't help!  Going to try to uninstall Mach and reinstall the previous version!