@MaxGyver

Thanks for the suggestions i will give them a try, the pitch should be right as i have tested it multiple times over 500mm distances
I will look at the dial indicator

I upgraded my oznest to ball screw and now appear to have a large discrepancy cutting a small hole for an MFT, 19mm when it is meant to be 20.8 but no apparent discrepancy between holes, which are pretty much exactly 96mm separated from edge to edgeas they should be.
I have analyzed the gcode and it looks right with the bit size which i have checked multiple times