The back of the Z-Axis was casted in UPH concrete

At this point i decided to go full in and build up the overall machine from scratch. I designed it in CAD and continued with the Spindle cartridge, since it is the most difficult part.

Turning the cartridge

Grinding the cartridge

Turning the spindle shaft

Machining the draw bar

Finished draw bar (hardend to about 54 HRC - C45k)

Spindle watercooling mandrel

Finished spindle cartridge (after some iterations.. :) )

Assembled in the spindle holder