tom koehler writes:

third Q: refers to a particular type of grind on a bowl turning gouge. Ah, I
am in pretty near perfect woodturner's isolation here, folks, so will need a
more thorough background in bowl turning gouge technology, here, I think. My
tool set is limited so far, to a set of basic Craftsman turning tools a
couple of home-brew tools, and a hefty gouge I bought from a tool catalog
many years ago. Has a peculiar looking (to me, anyway) grind on its end -
intended for bowl work. I've had mixed results with it, and so will be
looking for a clue, again.

There are several grinds for bowl turning gouges.
Irish, Ellsworth, Fingernail, etc.


This is a complicated topic, and I'm not a real expert.

But it has to do with the way the grind is done, and the shape of the
gouge.

Bowl gouges are deeper than spindle gouges.

Think of it this way.

For a roughing gouge, I place the gouge in a sharpening jig, and
rotate it around the handle as an axis. This is the easiest grind for
a bowl gouge.

If you were using a round nose scraper, the pivot point is not down
the middle of the handle, but a point near the end of the
scraper. That's a side-to-side pivot, instead of a rotate pivot.

In between, there are more complicated grinds. The fingernail grind is
like the roughing gouge, but as you get near the end, you push the
gouge up. So it pivots up and down.

In other grinds, the pivot point is off to the side. Imagine you stick
a piece of wood perpendicular to the tool, and rotate on that
point. This sort of grind needs a jig to be reproducible. Options a

Ellsworth jig
Wolverine Vari-Grind
Tormek Gouge Jig
Homemade jigs

The Ellsworth and Irish grinds need a jig. The advantages is the
number of different ways you can use a single tool. I attended a local
lecture, and I think he mentioned 7 different ways you can cut with
such a grind. Normally one rides the bevel to prevent digging in. One
variation includes holding the tool "upside down" and scraping with
the edge (and only the edge) on the bowl.

These techniques are hard to learn from a book.

But these grinds are very personal. I have a Tormek system, and one
recommendation is to use a standard grind, and using the Tormek
features, slowly change a tool's profile so that is is more like a
Ellsworth. Try it. That way you slowly get used to the new profile.

Here's one picture of a traditional and fingernail grind.

http://www.aawforum.org/photopost/sh...=5556&size=big

Here's more info
http://www.woodturningdesign.com/askdale/14/14.shtml
http://www.woodturningvideosplus.com/irish-grind.html

In any case, you don't want to ruin your favorite tool. Experiment
with different shapes, but I'd buy a new gouge for experimentation.