Why do I get a taper when turning?

[irving2008]

Hmmm, checked tool height by expedient of trapping a thin steel rule between work and tool - it remains essentially vertical.

Not sure what you mean by "angle the tool edge 5 past 12 on the clock", or rather I understand the words, not the intent... When the tool is square in the toolholder the leading edge is already angled to the work...

BTW, here is a pic of the test piece (its not intended to be a finished item), was just practicing turning to a diameter 12mm->10mm-> 8mm and using a die to thread the end. The 8mm ID thrust bearings and ballraces are a nice fit and a nut screws on nicely.