I just ran a job and zero'd the axis using REF ALL and mistakenly must have switched between Prog co-ordinates and machine co-ordinates. The axis were all zero's but I assume in the machine co-ordinates I still had a zalue for the Z axis, ran the job and whilst the machine was dropping down and traversing ready to make the cut it ramped down into the job and wrecked it.

I just wondered why Mach 3 has two lots of co-ordinate systems? When I zero the axis I check between them to ensure that everything is at 0,0,0 when I set the datum position in the lower left corner with the toolbit kissing the work.

Can anyone put it simply why Mach 3 has these two sets of reference points?