Quote Originally Posted by Shinobiwan View Post
Are you saying leave G90.1/G91.1 out the code and set for it within Mach for most reliable results?
No saying if it was G90.1 leave it and change the I/J mode in general Config to Absolute. Then vise versa if your code uses g91.1 and it' doesn't do what you expect then just change I/J Mode to Incremental.

Also doesn't matter whether using Conventional or climb milling you still want spindle spinning clockwise and M4 spins it Anti clockwise if connected.
Like I say I'd sort it now because one day it could bite if you ever decide to connect spindle for both directions.?