chuck:
I'm going to go the other direction. The most important part of arrow making is the nock and point taper. If they are not exactly in line with the axis of the shaft, you will have all sorts of problems. a taper that is not straight will give you crooked nocks & points. Picture the end of the arrow and four different arrows one nock points at 12 one at 3 one at 6 and one at 9:00 O'clock, each of those arrows will start from the bow in a different direction. Not good. The problem is the taper guide, in the type of tool that has been recommended its a hole. In order for the shaft to be guided properly the shaft MUST fit snuggly into that guide and there is too much variation in shaft diameters for that to happen. That's where the sanding disc comes in, either a homemade one or commercial made. The guide will be a "V" block the shaft will ride in the "V" and it will not matter what size it is or if its tapered and the taper WILL BE STRAIGHT everytime. Plus its adjustable for angle and can be fine tuned.
Bob