I have a Shapeoko 2 CNC mill with a dual Y stepper axis.  I have the A axis slaved to Y and I can jog all axis with no problems but when the Y axis tries to home the A and Y don't work in unison.  I tried setting RefCombination(10) in the 1024.set file but that did not help.  Please advise. I have a license copy of Mach3.

Do the Y and A have separate home switches, or do you just have one?

In General Config, there's an option for "Home Slave with Master".
Check it if you have one switch, uncheck it if you have two switches.

Do the Y and A have separate home switches, or do you just have one?

In General Config, there's an option for "Home Slave with Master".
Check it if you have one switch, uncheck it if you have two switches.

Just one home switch.  Y and A both drive the Y axis in a gantry system.

Did you have Home Slave with Master checked?
Is this with the parallel port, or a motion controller?

Did you have Home Slave with Master checked?
Is this with the parallel port, or a motion controller?

I haven't checked yet but probably not.  I'm using a UC-100

The external controller will be responsible for the slaved homing so probably best to contact the CNCDrive and see if they can help you out.
Hood

The external controller will be responsible for the slaved homing so probably best to contact the CNCDrive and see if they can help you out.
Hood

Hmm,  well I guess I could connect directly to the parrell port. 

The external controller will be responsible for the slaved homing so probably best to contact the CNCDrive and see if they can help you out.
Hood

I went back and read the UC-100 documentation and if I understood right all I need is the C10 breakout board?  I currently have the UC-100 going to a C10 breakout board which is connected to 4 DRV8825 stepper drivers.  Are the DRV8825 drivers necessary? 

You need stepper drivers if you have steppers. The UC100 is a motion controller, it recieves info from Mach and outputs pulses to the stepper drives which in turn move the motors.
The breakout board is simply giving you an easy means of connecting things.
Hood

You need stepper drivers if you have steppers. The UC100 is a motion controller, it recieves info from Mach and outputs pulses to the stepper drives which in turn move the motors.
The breakout board is simply giving you an easy means of connecting things.
Hood

Well I'm all good to go then.