"Ahh yes, I did figure that out. I was wondering if anyone could tell me what the A axis is for?
The real answer to your question is: "Depends on what your controller thinks it is" And, the answer, especially with low end controllers, can and will vary depending on how the control software has been written. In many cases the authors of these control software programs take some liberties, mostly to simplify for their userbase.
First we must differentiate between motor control channels and true axes, with axes being a defined direction of motion that may or may not have multiple motors. In Ted's case above, his controller uses the "4th motor channel" (which is controlled as "axis Y") and calls it "A". Other controllers call their second Z axis A, while others use "A" as the designation for a rotary axis. Of course, "B" is often used as a rotary axis on other controls.
Here is a graphic showing the industry axis convention, which must be adhered to when one uses a high end 4-5 plus axis CAD/CAM solution. In the lower end controllers, as you can see, liberties have been taken. Usually to simplify or lower cost. Of course, the X, Y and Z are followed by all controllers. U, V and W are the second linear axes (when separate control is needed) that provide motion in the same directions as X, Y and Z.
Depending on the controller, each of these axis designations could have multiple motors assigned to them, and they would be "paired" or "slaved" either by hardware or software. Hardware pairing simply connects the step & direction signal from one axis to two stepper drives. They are given the same signal, always. Software pairing provides 2 independent motor channels to a single axis and affords additional features, such as independent auto squaring or other features where adjustments may be needed between the 2 drive motors.
A, B and C are rotary axes that rotate around X, Y and Z as shown below. As you might notice, if convention is followed, a 4th axis rotary device could/should be called A or B, depending on its orientation (X or Y) or C if vertical. The "second Z axis" could/should be called "W". This seldom happens in our world as those who develop lower end controllers seem to chose a designation that either makes sense to them either for ease of use. In any case, they can (and do) call them whatever they wish, cuz it their stuff.
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