The A axis requires much different parameters to match with the X,Y and Z axis.
There are several settings to be checked as well;
General Config: check A axis is angular; check boxes in Rotational.
Tool Path Config: X - Axis of Rotation; check box Use radius for feedrate; check box A Rotation enabled.
The velocity settings for X,Y,Z are usually all the same, but the Velocity for A is much higher, as well as acceleration.
In my Analog Servo DSPMC milling machine, Steps per for X,Y,Z = 4096; Velocity = 180; Accel = 6
Steps per for A = 1536; Velocity = 1560; Accel = 270
In this setup, the Rotary table is 90:1, and I use this machine for commercial machine jobs, including many jobs needing
the rotary axis.
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In my stepping motor router: Steps per X,Y,Z = 10160; Velocity = 70; Accel = 30
Steps per for A axis = 2000; Velocity = 120; Accel = 40
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These settings were arrived at by testing, and long term use. The A axis speed with G0 or G1 is fully in sync with
the linear axis.
As you can see, the Velocity for the A axis is many times higher than the linear axis in both types of machine control.
Just experiment with the A axis settings, and keep raising values. At some point, the A axis motor will stall so just back off the setting. You can also write some simple combination moves using X,Y, and A using feedrate for a simple test.