Here's the "head unit" mounted on the mill.

This is a little closer view of the assembly showing the XL timing belt and pulley.

The motor mount and motor are all attached to a 1/8" steel plate which mounts to the slots on top of the Taig headstock. I made a special set of two long "T"-nuts with 4 holes in each to fit the headstock so the assembly is held to the headstock with 8 bolts ... it's solid.

The top part of the mount slides forward and back in order to tension the XL drive belt. Since the treadmill motor is variable speed belt changes are not required.

Here are the NEMA 34 replacement motors. They're "honkers!". Except for the X-axis motor which must travel with the table, the other motors are fixed in place. I had to make my own replications of the Taig motor couplers (with the little nylon pins) to fit the NEMA 34's.

Here's another view of the assembly dismounted from the Z axis with the detrius of electronic work scattered about.

Direct mounting to the headstock means the "power unit" can be dismounted from the mill and move to other machines. A couple I am planning are a sharpening rig (best to keep grinding operations away from the mill moving parts because of abrasion) and a mini-thickness sander to make strips of wood used to build up model ship hulls.

The controller box which houses the variable speed drive board and a relay to allow for computer control of spindle on/off. A DPDT switch changes from manual to computer control mode. Speed is strictly a manual operation as I haven't figured out a way to control it yet from G-codes. I need to make a cage for the exposed fan blades on top ... it really hurts!

I am building a 4-axis drive from 4 Pacific Scientific 6410's in order to drive the NEMA 34's (also PacSci) X,Y,Z and a planned rotary table. Most of the work is finished except cabling ... man I hate cabling!

there's more later ...