Well we have several correct answers to my question.
Getting the nock on in line with the axis of the shaft is by far the most important step in making arrows. let me explain why.
The nock end of the arrow is what receives the initial energy from the bow and is what starts the arrows direction of travel. Looking at the nock end pretend its the face of a clock, if you made four arrows and all the nocks were crooked. One pointing at 3:00 one at 6:00 one at 9:00 and one at 12:00 you can see each nock would start the flight of the arrow in a different direction. One direction would push the arrow down into the shelf and one would push the arrow into the riser which will magnify its error.
Applying the nock in my opinion is probably the most over looked step of making arrows, not only from being overlooked, but from construction technique. The biggest culprit is the devise used in making the nock taper.
At one time the nock standard was 11 degrees it has been changed to 11.5 degrees. This does not sound like much, but an 11 degree taper and a 11.5 degree nock will not go on straight. Plus pencil sharpener type taper tools quite often will put a crooked taper on the shaft, again impossible to place a nock straight on a crooked taper and add that to a 11 degree taper and a 11.5 degree nock equals more trouble.
The problem with this type of tool it the taper guide. Its a hole and unless the shaft fits very snug in that hole there's a good chance the taper will be crooked. When I was a young man, shaft diameter's were very consistant and it was possible to use that type of tool with success.
Today shafts will vary as much as +/-.015 with that variance the only type of guide that will work is a "V" slot or a "U" channel type that is used with the sander type tools. When setting up that tool besure the the taper matches the nock taper exactly. Also keep in mind if you use more than one brand of nock that the tapers are the same, they do vary.
Thanks to all the posted into my question, this was fun.
Bob