Colin, this may help with visualizing some of the angles:
http://www.sherline.com/grinding.htmThe main thing, and I mean most obvious once you look at it for a few minutes, is to keep the part of the tool that is
directly below the cutting edge from rubbing on the work.
The top of the cutting edge of the tool tool needs to be right on the centerline of the work piece.
On the front edge of the tool, that is, the end that faces directly toward the lathe headstock, it needs a small taper
from the cutting edge back toward the center of the tool so the entire front surface of the tool does not hit the
bottom of the hole at once.
Another way to do it is with an old drill bit. If you grind the end of a drill bit flat and look at the end you just ground off,
you will see that it forms two sides that make a kind of a 'hook' shape on the flutes. One of the flutes can be used as
a boring tool edge.
Remember, drill bits are quite flexible, so go at it easy. Also, if you grind off the end of a tool bit, take care not to get it
too hot. They represent a rather thin section of metal, and will over heat quickly. If you get it too hot, especially if it
a carbon steel bit, it will loose its hardness. That's not so much of a problem with HSS bits, but you still shouldn't get
them really hot.
What Lew asked is pertinent. What machine are you using for this? It would also be good to know what material you
are cutting. Steel, brass, aluminum, etc. ?
Dean