I am not happy with the Z axis design.  While its rigid and operates very well, its not an easy install. It needs some design changes and refinements.  For this reason I wont go into a lot of detail.

The Z axis drive assembly is made up of two generic NEMA 23 brackets, one on top of the other.

In order to brace the two mounts, I had to mill out the lower mount so the extended screws could span the two brackets.

I made a bearing mount that sandwiches the lower mount. Two thrust bearings and clamp collars are added to each side of this mount.

The Z drive assembly is attached directly to the X carriage with four #10 machine screws.

Notice the closeup of the Corian bearing block.  A corner has been broken off the lower block.  This is one of the down side to using Corian. Any features cut close to a corner can break under stress. I broke this one enlarging the holes.

The Z carriage consists of a plate with t two risers added to allow it to clear the Z drive as it is raised and lowered.

The torch holder is a attached to an adjustable extender.  I can also easily remove the extender and torch holder as needed for further experiments.

The four bearing trucks are attached to the risers.

The ACME nut is attached to the rear of the Z carriage.

The Z carriages is moved into place from the under side of the X carriage by removing the table.

I do this so I can have different carriages.  I'm currently working on a VFD controlled spindle carriage.

 

Conclusion

At this point the machine is ready for some serious testing.

Note that once I redesign the Z axis, I will post the results here: