The Tumbling Shaft bending jig needs to hold the bar ends in place during the bending operation. We will use two 4" blocks of steel, drilled and reamed to a close fit for the shaft to go through, which will be bolted to the bending jig. The idea is to hold the ends in line but allow the shaft to slide a bit to accomodate the bend.
In order to make two blocks with holes which are at the same height, we will drill and bore the holes in the lathe, then cut the bottom of the blocks in the mill to make the centerlines the same.
The holes are not on center in the blocks, they don't need to be. Using the wiggler in a punch mark and a dial indicator, we adjust the 4-jaw chuck until there is no runout indicated on the dial.