Re: [CAD_CAM_EDM_DRO] Brushed Servo & Motor Direction

Patrick wrote:

>Group,
>
>I'm working on a benchtop cnc machine (pro light 2k) that uses brushed
>servo motors for the axes. The problem is that when I command the
>homing routine, the machine travels in the negative Y until it trips
>the limit switch, and I get a "positional error." Z homes correctly,
>I don't know about X because the routine errors on Y, and X follows Y.
>Could the problem be as simple as switching the power wires on the Y
>axis motor? I've done some searching of the software, and there does
>not appear to be a user adjustable parameter for homing direction.
>
>

No, it gets a lot more complicated. If you just swap motor wires, it
will go crazy as soon as you turn on the servos. You'd need to swap
the A and B wires in the encoder, too. That will completely reverse
the axis, which I expect will get the sign of the motion reversed, too.
In other words, when you command a +Y move you will now get movement
in the -Y direction. If you manually move the machine to a place where
the home switch is in the -Y direction, then when moving in -Y it will hit
the home switch first, before the limit switch. This may require moving
the home switch to a different position.

Jon