I have just started using 4th Axis simultaneous (have used successfully for indexing in the past) and can't seem to get G93 (inverse time) working.

A command like: G93 Y0 A90 G23 F500  will have 4th Axis creeps along at say 1-2degree/m

G94 (with either correct rotational diameter or nominal one such as 0.0001 ) will see a rotational speed as displayed in the F value but I am told it is much better to use G93.

G0 and G1 with the 4th Axis alone or using the MPG keys seems to work fine and in line with the F value for G1.

I have just set up a new postprocessor (with Bobcad) to accommodate the 4th Axis so I am wondering if I have missed something obvious in the setup either of the post or in Mach3 (I have v3.043.0066). The other three axes all seem to be working fine with the new post.

I see earlier posts in the forum suggest there was a bug in Mach3 in relation to G93 but also a reference to that having been fixed some time ago.


Any suggestions appreciated.