The bracket was very easy to make using the CNC Wizards in Mach3, and especially the Newfangled Wizard. Here are some pix of the construction of the reader head bracket:
Love my 5/8" Helimill. Those APKT inserts cut through aluminum like butter!
I thought I'd map my X ballscrew just to check its accuracy with the DRO. Here is what I found with a series of half inch jogs:
The left axis shows the actual move of each commanded 0.5000" move as measured by the DRO. If the ballscrew were perfectly accurate, the graph would be a straight line centered on 0.5000".
You can see the righthand 40% of the ballscrew is qutie a bit more accurate than the left, although the first maybe 10% on the left is quite good too. Nevertheless, the whole screw moves to well under a thousandth of accuracy. You can also see that the errors are not cumulative, but are more periodic. The total error in 24 inches of motion was 5.6 thousandths and the screws are advertised as having less than 3 thou per 12", so this screw is within spec.
Mach3 has the ability to take such a map and use it to offset the errors, but I haven't played with that yet.