Thread: Bowl gouges V or U ?

They are photos of the same gouge, however I can't comment on the difference I have only ever used the u shape

Originally Posted by China

They are photos of the same gouge, however I can't comment on the difference I have only ever used the u shape

Thank heavens for that - I was squinting at them from all angles (on my phone) trying to see if there was a difference.

Originally Posted by auscab

V or U Bowl gouges .

Is one better than the other ? Does one suit a particular type of turning over the other ?

Rob

The following article by Roy Child has some reliable info on flute profiles.

A personal view of bowl gouges

Your P&N spindle roughing gouge is an example of a 'U' flute.

I prefer the 'V' flute profile (with any of the variations covered in Roy Child's article) and progressively stopped using 'U' flute profiles since 'V' profiles became available.

The 'U' flute profile is good for the bottom inside of bowls and truing up the face of faceplate work, but a 'V' flute with with a 65° bevel will do the same and is more versatile, IMO.

Doug Thompson's 'V' is the closest to the letter 'V' with quite straight sides, while most other makes have variations of the parabolic and centenary profile. The Woodcut BG tips are close to the classic parabolic flute profile and are good performers.

Tips

Any difference quickly becomes apparent when it comes time to sharpen, especially if using a jig with the same settings for both.

I find that v-flutes lend themselves well to grinding profiles with rounded wings while I can have difficulty getting a suitable wing (for my taste) while retaining the bevel angles I like on a U-flute.

So I prefer a v-flute for 'ladyfinger' and similar swept back profiles.

On t'other hand, I also prefer u-flutes for the gouges where the side bevels are simply more or less straight diagonals, rather than rounded wings.

As to why I prefer the different wing profiles, well... that's a case of different tools for different jobs.

Originally Posted by NeilS

The following article by Roy Child has some reliable info on flute profiles.

A personal view of bowl gouges

Your P&N spindle roughing gouge is an example of a 'U' flute.

I prefer the 'V' flute profile (with any of the variations covered in Roy Child's article) and progressively stopped using 'U' flute profiles since 'V' profiles became available.

The 'U' flute profile is good for the bottom inside of bowls and truing up the face of faceplate work, but a 'V' flute with with a 65° bevel will do the same and is more versatile, IMO.

Doug Thompson's 'V' is the closest to the letter 'V' with quite straight sides, while most other makes have variations of the parabolic and centenary profile. The Woodcut BG tips are close to the classic parabolic flute profile and are good performers.

Tips

Great links thanks Neil .

Those NZ HSS tips are an interesting idea. Good to see. Shows that you could just grind the end of a 200mm long HSS round bar and stick a handle on it . 30 mm of shaped end would probably last me for ever with bowl turning.

I do like the idea of a few new Thompson gouges to though . Spindle and Bowl.

I was wondering if that P&N roughing gouge I have would be good as a big bowl gouge with a swept back grind .

I constantly have big wet gumtrees needing chopping up (firewood mainly ) and need something better with my chisels to have a better go at wet turning .

Everything I have is spindle orientated atm .

Rob

Originally Posted by Skew ChiDAMN!!

Any difference quickly becomes apparent when it comes time to sharpen, especially if using a jig with the same settings for both.

I find that v-flutes lend themselves well to grinding profiles with rounded wings while I can have difficulty getting a suitable wing (for my taste) while retaining the bevel angles I like on a U-flute.

So I prefer a v-flute for 'ladyfinger' and similar swept back profiles.

On t'other hand, I also prefer u-flutes for the gouges where the side bevels are simply more or less straight diagonals, rather than rounded wings.

As to why I prefer the different wing profiles, well... that's a case of different tools for different jobs.

Thanks Skew. Good info . Having a couple of types to try out and play with is probably the way to go .

Rob

Originally Posted by auscab

I was wondering if that P&N roughing gouge I have would be good as a big bowl gouge with a swept back grind .

The answer I must give to that in this open forum is 'No'.

The big P&N spindle roughing gouges were designed for spindle work, in other words, for removing large amounts of wood along the wood grain on spindles, for which they are ideal.

But, a big gouge like that, regardless of the grind, can get you quickly into big trouble on cross grain work. It can self-feed with a big bite into the end grain with catastrophic results! To call it a catch would be a gross understatement... it would be more of a 'hoik' of either the blank, the tool or the turner; or all three!

My advice to anyone new to cross grain work is to use bowl gouges, for which they were designed.

My practice is to only use my bowl gouges on cross grain work, with the occasional exception of a spindle gouge to roll beads on the outside of a bowl.

I might have a slightly different conversation (but only very slightly) with an experienced turner, say after their first thousand bowls, by which time they will have enough expertise themselves to know what not to do...

Ive seen and read about not using SRG in bowls so intend to steer clear of trouble .

If a bowl gouge is a U shape and a SRG is a U shape then isn't it just the swept back grind that is the only difference ? If they were both ground the same then whats the problem ?

My P&N SRG is 25mm and the largest Thompson Bowl Gouges U or V in the link I put up are 5/8", almost 16mm. Is it the extra size that's the danger ?

Rob

Originally Posted by auscab

Ive seen and read about not using SRG in bowls so intend to steer clear of trouble .

If a bowl gouge is a U shape and a SRG is a U shape then isn't it just the swept back grind that is the only difference ? If they were both ground the same then whats the problem ?

My P&N SRG is 25mm and the largest Thompson Bowl Gouges U or V in the link I put up are 5/8", almost 16mm. Is it the extra size that's the danger ?

Rob

My larger P&N SRG is partly ground back on the wings...

P&N 1&1-4in SRG.jpg

But that doesn't overcome the issues with using it on cross grain work.

The problems with using it for that are twofold. The most significant is the high straight sides on the 'U' profile. Here is the above SRG viewed end on...

P&N SRG end on.jpg

Those high straight sides are trouble waiting to happen when they make contact with end grain. That would be like using a skew into gross grain... imagine using a skew uphill on an ogee in spindle work!!!!

And, yes, the large size of SRGs is another factor, but less significant than the high straight wings on the SRG flute.

I'll try to dig out an image of a 'U' bowl gouge to illustrate the difference.

Originally Posted by NeilS

I'll try to dig out an image of a 'U' bowl gouge to illustrate the difference.

OK, here is a what is typically called a 'U' fluted BG...

Dway 3-4in BG.jpg
D-way 3/4" U-fluted BG

Almost all of the flute is curved and with next to no straight edge on the upper wings. Even if some of that upper edge were to get into the end grain it is so minimal that it can still be controlled, especially if you have a longer handle, which I like to have on all of my bowl gouges.

Here is another so-called U-fluted BG...

Crown 1in BG.jpg
Crown 1" U-fluted BG

That one is the same bar size as the 1" P&N SRG. It takes a big bite, but again, is manageable because the entire edge is curved and the cut can be controlled with just the required amount of bevel rubbing. Most of my handles are long but light, however, I do have a much heavier handle on this one... doing a session with it is like doing a workout at the gym!

My big P&N SRG is just 1/4" larger, so it's not the size that has me keeping it away from end grain work, but its unforgiving flute profile.

Originally Posted by NeilS

My big P&N SRG is just 1/4" larger, so it's not the size that has me keeping it away from end grain work, but its unforgiving flute profile.

Looking at the end view image I posted of the P&N 1-1/4" SRG it may not be so clear about how much danger zone there is on its upper wings, so I've added some graphics to make it more obvious where the trouble zone is...

P&N SRG - touble zone.jpg

And for clarity on what we are referring to with the terms Parabolic (including catenary), U and V flutes, here is an image of the three side by side...

Parabolic U and V flutes.jpeg
From left to right,
Parabolic, U and V flutes

Doug Thompson's Vs have quite straight sides...

T 15v 5-8in 1.JPG

The benefits of the Parabolic vs V vs U profiles are more apparent when it comes to the various jig settings for the more "specialist" grinds - i.e. Ellsworth, Irish, "bottom feeder", Stuart Batty 40/40 grind etc.

The flute shape & design is important when it comes to your preferred style of bowl turning, whether you prefer "push" (nose) or "pull" (wings) cuts.

The shape of the flute determines the length and shape of the wings at particular jig settings. Some combinations are simply made for each other and produce a bowl gouge with a "user friendly" well shaped nose and wing profile, that has forgiving transitions from nose to wing. Whilst other selections of flute / jig settings produce an almost "un-useable" tool that is prone to catches because of the nose & wing shape and the abrupt transition/s from nose to wing.

Finally, open shallow forms i.e. platters and shallow bowls are more forgiving of flute shape and preferred grind, whereas deep forms such as vases typically require a different bowl gouge (flute & grind) to complete the inside bottom of the vase than that used for the inside and outside "sides."

Originally Posted by Mobyturns

The shape of the flute determines the length and shape of the wings at particular jig settings. Some combinations are simply made for each other and produce a bowl gouge with a "user friendly" well shaped nose and wing profile, that has forgiving transitions from nose to wing.

It was Gerry Glaser who explained for me the close relationship of the flute profile (end view) and the matching grind (as seen from top view) and how these should be a mirror image of one another for the optimum grind for that flute profile. So, for example, here is the end view of the parabolic flute profile on a Vicmarc BG....

IMG_1168 - sm.jpg
Endview of flute

And, here is where the edge should be located to optimise for the above flute, as viewed from above...

IMG_1167 - sm.jpg
Top view of where edge
is to be formed

And, the two above images combined with the end view of the flute profile inverted and added below the top view of the edge profile to show the mirroring...

VM BG flute & edge mirror image .jpg.jpg

To explain a bit further, attached is a diagram from Gerry on this.

.

Originally Posted by NeilS

And, the two above images combined with the end view of the flute profile inverted and added below the top view of the edge profile to show the mirroring....

I've never heard it explained like that - the mirroring, I mean - but a quick look at my favourite bowl gouges show they're close matches. Not perfect, but close enough.

I've also inherited a couple of bowl gouges that I dislike using and put aside for future reshaping. They're quite a ways off. Then again, so are a couple of other gouges I am happy with, but they're for specific functions and I tend to only use either the wing or the nose.



Interesting stuff!