I am using Bobcad's postprocessor. It inserts the following line into every program "G53 Z0.", which causes the Z axis to plunge down into the table until it crashes (the top of the part is supposed to be zero). What's the purpose of this command? I have to go through every program and delete it before I can run the program.

THe G53 Z0 is telling it to go to "machine" zero. Kinda odd to have it in the regular Gcode output. I would look for another post for BOBCAD that did not include that move.

BUT then again normally your machine Zero would be a the top of Z travel a safeZ so to speak.

(;-) TP