Struggling With My Brain

I sometimes wonderb how disabled I am, but the last few days of programming this CNC mill have persuaded me that it would not be wise to return to software engineering.  The manual that Sherline hands out with their CNC mill emphasizes that you should know exactly what each command will do before running the program. 

I had wanted to improve the finish on the completed parts, because there is a series of stripes in the direction of milling.  It is only appearance; there is no detectable edge, so .001" or less difference.  But I thought I would smooth it perpendicular to the direction of the milling.  So I modified the excavate program to mill in the X direction, then Y, instead of X then Y.  The excavateyx program would be called with parameters to remove .0001" of material.

Fine.  I wrote the program, and failed to notice that when computing the end of the X movement, I needed to subtract the mill radius from the destination.  The right test stratgey would have been to start the program, single step each line, then override the feed rate for the first line.  Nope!  The mill banged into the edge of the workpiece at 6 in/min, the rotation then yanked the Y axis towards the table hard enough to strip the teeth from two star gears that control the Y axis feed.  Fortunately, these are $5 for both parts, but In ordered two, in case I screw up again.