Set up the spindle of a dividing head in the horizontal plane accurately. More accurate than using the degree markings on the side of the head.
This is a BS-1 dividing head and supposedly has a Brown & Sharpe #7 taper. But it is a clone, and hardly anyone makes B&S tapers. I have found that a Morse 3 taper fits perfectly and I suspect that was what was used in the spindle.
I used an MT3 alignment bar, which is about $30-40. There is no reason why one could not do the same technique with a bar held in the chuck, though with the usual caveats that removing the bar from a 3-jaw chuck and reinstalling it may change the results.
