Quote Originally Posted by CraftyGeek View Post
Thats a great start - thanks....simple too.

I just need to work out how to set the zero reliably & accurately now....any pointers on this?
Again, consider fixing the jig to specific fixing points on the maching table/bed. If your bed is MDF, then one option is to drill through and use tee-nuts inserted from underneath. These will then act as a fixed location for the jig base.

In all cases you need some way of bringing your cutter back to a known, fixed, starting point... or some way to calibrate it to a known point. This is where homing switches are useful but how useful depends on the accuracy you are looking for.

On a milling machine you rarely rely on the table location but zero off to the workpiece using a rotating edge finder tool in the spindle.

In this case you'd zero off to the jig... jog to the jig edge util the tool gives a zero indication, then set this as a known value in Mach3 or whatever the software you use. Repeat on the other axis.