After drilling the base plate, the next item was to drill the supports to the same pattern. This was a bit nerve wracking as there is not much wiggle room for ‘adjustments’.
To align the holes in middle of the supports I used a .375 rod in the mill arbor, and a parallel to make it align with the top surface of the support. The spindle was then in the middle, the vertical was then locked into place. The other position was aligned each time with a spotting drill and then drilled 4.2 for the m5 SHCS.
A very sophisticated depth stop was rigged up to not drill too far into the supports.
To do the tapping I digressed into making a tapping block, just a lump with appropriate clearance holes for the various metric taps. I cut a block for Imperial ones as well, will get to that when it is needed.
Final result is the 3 supports square and vertical. Next up is some measuring to adapt the shaft dimensions to the .375 plate (instead of 10mm per the drawings)