Bowl gouge grinds

[Jack Tyree]

I recently got a DT 1/2" U shaped bowl gouge and use it with the standard grind it came with. I use the Wolverine system and have no trouble duplicating that grind. I also have a 3/8 V shaped gouge and use it with the standard grind also, but I guess because it is a V shape it seems to cut quite a lot nicer. I meant to get the 1/2" in the V shape too, but I messed up, I guess. I want to experiment with more of a side grind now and want to get another 1/2" to keep in that grind. Should I get a U shaped or a V shape for that grind? (And why do they cut so much differently?)

[Steve Schlumpf]

Jack - everyone will have a different opinion on this - but - seeing as how you already have a 'U' shape - I would go with the 'V' shape and then you can actually compare both and see what works best for you.

I have the 5/8" V from Doug and it is my go-to gouge for everything! I can rough out bowls and hollow forms or make extremely fine cuts... but it does come with practice!

I have a swept back grind on my gouges and I use the wings more for sheer cuts than anything else but can take off some seriously wide curls when roughing out a blank!

[Jack Tyree]

I knew you used a swept back grind on your gouges and hoped you would reply. I decided to try and learn to grind and use them after watching a video of Tim Yoder taking wonderful shear shavings on the outside of something(?)

[Steve Schlumpf]

Jack - I do have a fairly radical swept back grind but it is something I worked in to over time and something that works for me and my style of turning.

If you are just starting out with a swept back grind - be aware of those sharp wings when you go to use it - or YOU WILL SLICE your hand! I wear a glove on my left hand and it has many slices from when I hold the gouge against the tool rest! Just something to be aware of!

[Bernie Weishapl]

I also have a 5/8" and 1/2" Thompson gouges with a really swept back grind. I like the long swept back wings for doing the vertical shear scrape like Bill Grumbine uses. It really makes a smooth surface especially where there is a lot of tear out.

[William Payer]

I have four Thompson bowl gouges (3 "v" and one "U") along with a couple of Sorby bowl gouges/ I sharen them all with the same jig setting on my Tormek ( protrusion of 75 mm and on #6 position) Although I like the Thompson gouges I find the Sorby's to cut much cleaner. I think the Sorby's are more of a "U" shape. I just wondered if anyone else has noticed some designs cutting better than others with the same sharpening settings?

[Thom Sturgill]

I have a DT 5/8" U in a conventional grind with the heel rounded that I use for the transition area on bowls. I also have 2 other 5/8 - a crown and a Ellsworth sig. I also have DT 1/2" and 3/8" Jimmy Clewes V (sharper than the normal V).

On the U more of the 'nose' gets involved when cutting with the point because it is so much wider. The Ellsworth seems to get sharper than the others. Its flute is parabolic which effects the shape of the wings. The Clewes flute is a sharp V with straight sides giving a good straight wing for shear cutting.

Differences in grinds, steel, and flute design all make them hard to compare, but also make each perform different tasks better than another. I just have to remember which is which.... then a little sometimers kicks in:eek:

[Harlan Coverdale]

Should I get a U shaped or a V shape for that grind? (And why do they cut so much differently?)

I find it's handy to have both U and V shapes. I tend to use the V shape on the outside of bowls, since I like the shearing cut I can get with the relatively long wings. I like the U shape inside a bowl, since I can get a shearing cut with the more rounded tip of the gouge. I think if you have both in the same size(s), you'll find certain tasks that one excels at over the others.

[Jake Helmboldt]

How does the Thompson V-flute compare to the Sorby? I've seen some posts say the Sorby is parabolic while others say it is more akin to a U.

[Neil Strong]

There was a time when all we could get were U fluted gouges, so still have a few of them in the tool rack but only reach for them very occasionally now that we have so many V flute (actually Catenary or Hyperbolic cosine or Parabolic) gouges available.

Perhaps the one U fluted gouge I still reach for quite a bit is the big P&N roughing gouge, but other than that I wouldn't bother buying another U'ee.

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[Josh Bowman]

Jack - I do have a fairly radical swept back grind but it is something I worked in to over time and something that works for me and my style of turning.

If you are just starting out with a swept back grind - be aware of those sharp wings when you go to use it - or YOU WILL SLICE your hand! I wear a glove on my left hand and it has many slices from when I hold the gouge against the tool rest! Just something to be aware of!
Steve,
Could you post a picture of your grind? My mentor has me using one that has long wings. I duplicated it on my Tormek and they call it an Ellsworth grind.
Thanks

[Dennis Ford]

I agree with Harlan, both shapes have their uses. If I had to choose just one it would be the "V" shape but a "U" shape with a conventional grind at 60 - 70 deg works great for the bottom area of deeper bowls.

[David Woodruff]

I truly love the radically long swept back grind. With practice, really delicate cuts can be made. I have GLASERS(gloat, gloat 0 .25 up to.75 with grinds of both varieties. The V-15 is awesome.

[Richard Madison]

The Sorby "V" is shallower than the DT. I used to think is was a "U". The BB "V"'s that I have are much sharper/deeper than the DT, and harder for me to control. I use the nominal swept back grind that Doug supplies, except on the Sorby which has a straight "traditional" grind (good for shear scraping). As mentioned, wings of the DT 5/8" "V" are good for shear cuts, similar (I think) to planing cuts with skew.

[Doug Thompson]

The most common bowl gouge is the V shape, if you look down the flute at all the different brands on the market you can see that most are close to each other. This basic shape does most everything well because the small radius is easy to control. The U shape because it has the large radius will shear the wood better on a finish cut but roughing the larger nose radius IMO is harder to control. When you think about a U shape flute think push cut, Stu Batty, dry wood and finish cuts.

When you sharpen a bowl gouge remember you follow the flute shape, look down the flute then look straight down at the grind, they should look about the same.

[Steve Schlumpf]

Josh - to see photos of my gouge grind, go to post #9 in this thread: http://www.sawmillcreek.org/showthread.php?t=141238

[Jack Tyree]

Looking at the picture of Steve's grind, I think I would get in serious trouble trying to learn to use it correctly, and even getting the grind right on my jig. I follow the instructions Doug sends out and it duplicates the grind perfectly. I assume what you meant in your reply, Doug, is to look straight down the flute from the end.(?) I have watched the You Tube Video from One Way on the Wolverine jig and how to do the fingernail grind, and planned to follow that and not get anywhere near as radical as Steve's grind.

Don't get me wrong Doug - I really like the 1/2" U shaped gouge, but as every else knows I'm trying to teach myself how to use gouges, and it's harder because I don't know how to, to begin with. I feel pretty proud so far because I have not had any major catches or fowl ups so far. The only trouble I had with it was an 11' inch shallow bowl which got dry and changed shape between the outside shaping and the inside hollowing. Push cuts were prone to vibration and a lot of tear out. Switched back to the 3/8 V shape and it cut a lot better with almost no tear out. And believe it or not, I finished the last 1/8" inch or better of hollowing with shearing pull cuts with the 1/2" without any catches or tear out. (This was before I knew you weren't supposed to do that!)

But anyway, Doug, when you get some free time, if you could post the settings on the Wolverine jig for a not so radical swept back grind, it would be greatly appreciated, and Bernie, if you could post a picture of the grind on yours the next time you get a chance, I would appreciate that too. If I can see the grind I want, I can pretty much get there without wasting to much metal. Thanks again to everyone else for your advice/comments too!

[Doug Thompson]

Jack, look down the flute from the ground end then look straight down at the grind. The U shape flutes work well when the tool is rolled almost closed (about 2:30).

The jig settings on my site is a very good starting point, when the leg setting is changed on the jig will make the wings thinner or thicker on a bowl gouge. Thin won't hold up and thick doesn't cut well.

Steve's grind looks a bit radical but when you remove the very long wings it's a solid good looking way to grind a tool... do note the secondary bevel.

[Neil Strong]

When you sharpen a bowl gouge remember you follow the flute shape, look down the flute then look straight down at the grind, they should look about the same.

First time I've heard that axiom.

Must check it out.

Thanks Doug.

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[Doug Thompson]

First time I've heard that axiom.

Must check it out.

Thanks Doug.

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That's how you keep your cutting angles and the reason for different flute shapes. A simple example that I see to often is a U shape flute ground to a point like a V shape bowl gouge... the wings are in the range of 50 - 70 degrees, that won't cut butter.

[Jake Helmboldt]

That's how you keep your cutting angles and the reason for different flute shapes. A simple example that I see to often is a U shape flute ground to a point like a V shape bowl gouge... the wings are in the range of 50 - 70 degrees, that won't cut butter.

Doug, when you refer to the wing angle, how is that measured (and for clarification, what is the actual angle you are referring to)?

Thanks, Jake

[Neil Strong]

OK, had a look at my Vs & Us and they seem to conform to Doug's axiom, more or less. The Us are spot on (first pair of photos) and the Vs are close enough (2nd pair).


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[Doug Thompson]

OK, had a look at my Vs & Us and they seem to conform to Doug's axiom, more or less. The Us are spot on (first pair of photos) and the Vs are close enough (2nd pair).


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Thanks for the pictures, that's the basic idea of why we pick a V or U shape flute... they are ground following the flute shape. The trouble begins when a U shape flute is sharpened to a point like the V shape gouge cutting angles are lost. You can measure the wing cutting angle but I not going there, it's another measurment that doesn't need to be perfect. Bowl gouges need a deep flute so the cutting action will drive the tool into the rest.