[bigz1]

I have used Imperial ACME rod for my machine and used inches to set up in motor turning. How can I get mach3 to default to mm on the DROs when starting up rather than typing G21?

Also for squaring slaved motors x and a, is it standard practice to use the Homing offsets?

[ger21]

Just set up the machine in mm. You can use two different configurations, one for inches and one for mm's.

Or, try putting G21 in the initialization string in Config>General Config

[bigz1]

Thanks Gerry. Put it in string.