Cut a dowel and it was heavily tapered, so I chased down that problem this evening. The taper was .020" and did not seem to have any effect on length, a short dowel was tapered as much as a long dowel...how strange.
I checked the cutter to make sure it was set the same distance from each center....probably 10 times, all was well.
Finally I noticed that when I tighten the tail center the tailstock would rock slightly and put the stock upward just slightly. The result was that it would cut smaller on that end. I fixed this by filing the tail stock seat until it sat perfectly flat and also matched centers exactly. It was not significantly off, but enough that it seemed an error worth removing.
Now I'm down to a difference of .005" from end to end on a short dowel. I'm sure I can knock that tolerance down a bit.
Spun it up to full speed and made a nice smooth pass on this stick of gumi. This will become a chisel handle.
Bumbling forward into the unknown.