Found a cool post about a person having the same problem. The issue I am having is that my robot brackets are about 2 mm to small see picture.
They should be 41mm wide.
Link to post about: Thing-O-Matic: Axis Calibration vs. ABS Shrinkage
'The money quote is that ABS shrinks just about exactly 0.5% as it cools. That’s modulo the starting temperature, the molding process, and so forth and so on, but it’s a pretty nice match."