Peter,

Yes I understood your thining, but I would prefer to do them at the same time (not bore them simultaneously, but in one session without tearing the fixture down). Since I want to pour both bearings at the same time. Your approach would require two bearing blocks, to fit the unbored bearing as well as the bored one. Unlike kingpins they will be significantly different sizes - the unbored one approx 1" dia, bored it will be 1.25" +0.002/-0.000.

I am planning to use 20mm dia round rail as rhis is cheap to get and guaranted straight. Although it is hardened so I will need to gring some surface off bore milling some flats on it and drilling 3/4 way through for a 6mm cutter and the remainder of the hole 3mm tapped M3 for a pusher screw. There will also be a 3mm locking screw at right angles. The end thread will be used to push the cutter out and so accurately set the boring size (1 turn of screw = 0.5mm)