This is what I mean by the having a small flat at the bottom. I measured the final hole and it's 33.6mm. It started at 32mm aswas very snug on the dimple die.
The 'coining' mark is 38mm the same as the male die. You can also see that this test piece wandered as the die was compressed. I think I need to work out a way of clamping the punch and the workpiece.
Should I just use a 38mm hole cutter?
Should I stop worrying?