I'm just about to start modifying a 6 x 26 Knee milling machine for CNC operation. I intend to use mach3 eventually to control the stepper motors

The machine has a vertical Knee movement in the Z axis as well as quill movement in the same direction.
For small movements, driving the quill up and down is preferable but this will need to be combined with the movement of the knee for larger movements.

Can mach 3 cope with sending signals to two steppers that will act on the same axis?

Apologies if this seems a daft question but.....

TIA

Bob

You would have to configure one as another axis (A, B or C) and command that from within your code.
What some have done is use the knee for setting the tool offsets and the quill for the actual machining, that will likely be your best bet.
I think Ray (Himykabibble) posted the macros he used for this so may be worth a search.
Hood

Thanks Hood,

I will have look for that. At least for now, I can continue to plan my conversion in the knowledge that it is possible.

Bob

OK just a fair warning. Mach3 cannot split the Z moves between the 2 axis UNLESS you can get a post to modify a CAM program to do it and i have never heard of it happening so far.

Yes you can use the Knee axis to do the tool comp but so far that is the best I have seen happen. 

So you can drive the Knee as Z or drive the quill as Z but not both at the same time.

Just a thought before you start, (;-) TP