[ger21]

Looks like it may be a bug in Mach3? What version of Mach3 is this?
Have you tried a different version?

[Olavi]

Versio is R 3.043.066

[Mauri R]

Kai,
You have the latest Mach 3 version.
It is always good practice to use the Post that suits the machining you intend to do.
If doing 2.5/3 Axis then use the 3 Axis Madcam Mach 3 Post.
Also make sure the Post is setup for your Mill.
You do have a command to the A axis on Line 7 you have G00X-30Y0A90.0
Regards,
Mauri.

[dwneumann]

Kai, my guess is this is electrical noise on the cable going to your A axis motor. If you have electrical noise in an open loop setup (stepper motors) then the A axis motor will turn but the DRO won't show it. If you have electrical noise in a closed loop setup (servos) then you can see the A axis motor move and it will show on the DROs. Do you have a closed loop setup?

Is the wierd A axis motion repeatable? (i.e. does the A axis always move exactly the same amount at exactly the same line of G code)? If so it is not electrical noise.
If you put RF chokes on both ends of all your cables (or wrap them in aluminum foil) and set the Mach3 anti-bounce parameter to a high number does that change the A axis weird behaviour?
Regards,
Dean