Best grind for Thompson “U” bowl gouge?

[Mike Novak]

For those of you that have a Thompson U bowl gouge, what grind do you use on it? I bought a 3/8 for detail work and can’t find a grind that works well with it.

I’m learning that matching the grind to the tool profile is critical. On my Sorby, Ellsworth is best, but on my Thompson “V” the Glenn Lucas grind is much better. I can’t tell the difference by eye, but performance difference is amazing.

 

[Lyle Jamieson]

The "U" flutes have a lot of limits. They are only good for push cuts and will not work well for pull, scrape, or sheer scrapping cuts. So the swept back wing grinds like I use and David uses will not be very efficient with the U. Mine are parabolic. The tip angle I use is 60 degrees but the 40-40 and other grinds will work, and for push cuts only.

 

[robo hippy]

For detail work on bowls, I prefer a spindle detail gouge. The U or half round flutes are best for BOB (bottom of bowl) grinds. They can also make good smaller SRGs. They do not make for a good swept back grind or 40/40 grind, and believe me, I tried!

robo hippy

 

[hockenbery]

3/8 for detail work and can’t find a grind

I use a convex Michelson grind on my 1/4” thompson gouge 3/8 bar. A traditional grind would work ok with a bevel anywhere from 45 to 60.
The convex bevel is great for turning tight coves on a hollow form neck, for hollowing balls…..

For most turning my favorite gouge is the Jamieson gouge made by thompson with an Ellsworth grind.
It is the best tool I have found for the slicing cut and the flute up shear cut inside bowls and fog cuttin natural edge rims.
The Jamieson has a slightly wider flute that makes it work better.

Hollowing a ball with the 1/4” gouge (3/8 bar)

 

[Michael Anderson]

The only U shaped flute I have is a 3/4” Thompson, exclusively as a bottom feeder. I keep a traditional grind, around 70-75 degrees.

 

[Emiliano Achaval]

The only U shaped flute I have is a 3/4” Thompson, exclusively as a bottom feeder. I keep a traditional grind, around 70-75 degrees.

I have mine at 60. Like @Lyle Jamieson and Stuart Batty. Anything after 60 it becomes grabby in my experience. I have a second one at 50 for the transition area of calabashes, although lately I prefer a Hunter Tool for that.

 

[Michael Anderson]

I have mine at 60. Like @Lyle Jamieson and Stuart Batty. Anything after 60 it becomes grabby in my experience. I have a second one at 50 for the transition area of calabashes, although lately I prefer a Hunter Tool for that.

Fair enough. I'll try a re-grind at 60 degrees on the next batch of bashes and see how it works out.

 

[Rusty Nesmith]

I have a 1/2” and grind it at 55 degrees. I also grind the bottom half of the bevel.

 

[Bill Blasic]

The U gouge that Doug sells is best used with the grind that comes with it. Swept back grinds will not work due to the straight sides. I have one (or did have one) somewhere where I put wings on it. It just does not work. All my years in the booth talking with turners I have been asked V or U? I always state that for me the U is aggressive and hard to control and I prefer the V. You would be surprised at the number of folks who are just the opposite of me. But none use wings.

 

[robo hippy]

I went and checked my bevel angles since I now have one of those angle measuring tools. All of my BOB tools and scrapers are about 65 degrees. I do have a slight sweep to the nose rather than a square one. I have seen Mike and Stuart using BOB tools, and they pretty much have the flutes straight up. I have my flutes over on the sides, at 90 degrees. I figure that gives me a higher sheer angle.

I did try several times to get a 40/40 grind on my U flute tool. It does not work.

robo hippy

 

[Nick Valenza]

Fair enough. I'll try a re-grind at 60 degrees on the next batch of bashes and see how it works out.

So the higher the bevel angle the more aggressive? Is this the same for traditional scrapers? Higher bevel angle, more agressive the cut?

 

[Neil S]

The "U" flutes have a lot of limits.

Understatement of the year there Lyle!!!

Before the more versatile parabolic and V flutes became widely available I had a few U fluted gouges in my tool rack, but never liked them very much. OK'ísh for inside bottom work, but I found with a high nose bevel angle grind (65deg) on a parabolic or V fluted gouge that they were equally good for doing that cut, so I haven't had a U flute in my tool rack for the last 25 years.

 

[John Hicks]

I use a convex Michelson grind on my 1/4” thompson gouge 3/8 bar. A traditional grind would work ok with a bevel anywhere from 45 to 60.
The convex bevel is great for turning tight coves on a hollow form neck, for hollowing balls…..

For most turning my favorite gouge is the Jamieson gouge made by thompson with an Ellsworth grind.
It is the best tool I have found for the slicing cut and the flute up shear cut inside bowls and fog cuttin natural edge rims.
The Jamieson has a slightly wider flute that makes it work better.

Hollowing a ball with the 1/4” gouge (3/8 bar) View attachment 58113

I'll second the Jamieson gouge. It's like a new invention

 

[Mike Novak]

I guess I will chalk this one up as a learning expense. Maybe I’ll grind the sides down and see if it will make a passable spindle detail gouge or vortex.

Thanks

 

[hockenbery]

I guess I will chalk this one up as a learning expense. Maybe I’ll grind the sides down and see if it will make a passable spindle detail gouge or vortex.

Thanks

consider giving this a try. Put a traditional grind on it with a 45 degree bevel. To sharpen Roll it on a platform.
This is a trick I learned from Jimmy clewes for finish turning the first inch inside a bowl.

This is a problem area returning a dried bowl for many turners.

I can often improve the surface 1 or 2 sanding grits using my 3/8 diameter bar u flute
I use a Michelson grind but that has a learning curve to grind. the traditional does a real nice job and is easy to grind.
See the fine shavings.

 

[Dean Center]

I guess I will chalk this one up as a learning expense. Maybe I’ll grind the sides down and see if it will make a passable spindle detail gouge or vortex.

Thanks

The U flute gouge has a very deep flute, while the spindle detail gouge has a very shallow flute. The Vortex has none. This does not seem like a strategy likely to produce a happy outcome.