Cutting accurate tapers within OD

Make a taper plug to measure the inside taper. Use prussian blue. For a one off this will be the fastest, easiest, and most accurate way. It depends on how accurate you want the taper to be and how long it is. But assuming the taper is short enough to cut with the compound making a plug is fastest. If you have already the male taper then put it in the lathe, get it running true, then use an indicator on the tapre to set the compound. The indicator tip must be on the center line of the spindle and the boring bar tip must also be on the centerline. ERS

Prussian blue. The few times I've done it with the compound, it was set to angle as close as I could with a sine bar, then get close to dimension, then really light coat of blue on mating plug, adjust, try light cut, blue, repeat. It usually went pretty quick. Just don't make your adjustment of the angle too big.

Pete Keillor