Technique question - A cove in a cross-grain/bowl turning

[Hermit]

I know that the basic rule is to cut 'downhill', with the grain, but aren't sure in the case of a cove in the outside of a cylindrical cross-grain turning. To cut with the grain, the cut needs to be started in the middle of the cove, tapering off shallower toward each side, but this doesn't feel right.

It feels more 'right' if I do it like a spindle turning, working from each edge of the cove toward the centre.

Any thoughts/advice appreciated.

(I could use my carbide tools and work either way, but want to use a bowl gouge for more practice.)

[stuffy]

To cut with the grain supported in cross grain orientation you need to cut from the bottom of the cove out.

The problem with that is you have to get to the bottom of the cove somehow. So a scrape or cut against the grain is necessary for clearance.

If using a bowl gouge make sure the edge is presented at a steep angle, flute at 3 or 9 o'clock. You don't want the edge to contact head on so to speak, as in using a spindle roughing gouge. Even if Tim Yoder thinks so.

For a small cove some scraping is inevitable even with a bowl gouge.

HTH.

:)

[Hermit]

To cut with the grain supported in cross grain orientation you need to cut from the bottom of the cove out.

The problem with that is you have to get to the bottom of the cove somehow. So a scrape or cut against the grain is necessary for clearance.

If using a bowl gouge make sure the edge is presented at a steep angle, flute at 3 or 9 o'clock. You don't want the edge to contact head on so to speak, as in using a spindle roughing gouge. Even if Tim Yoder thinks so.

For a small cove some scraping is inevitable even with a bowl gouge.

HTH.

:)


Good one. Thanks Stuffy, for the detailed answer. :2tsup:

Although it felt wrong, compared to a cove in spindle turning, that's what I thought.

I should have mentioned, too, it's a 75mm wide cove, not a narrow one, so it's not too hard to start from the middle. About 10-15mm deep. (I want a bowl with concave sides.)

For a narrow cove, I'd probably start from the sides as you say, against the grain, then scrape to finish. Just wasn't sure with this wider one. I could always cheat and use a round carbide cutter, but want to learn the right way to do it with a bowl gouge.

[chuck1]

I like to use my detail gouge in the same manner!

[tea lady]

Yes detail gouge would work quite well. Similar to hollowing an end grain vessel but inside out. :think: If you get me. :roll:

[Hermit]

Thanks Charlie and Anne Maria. A detail gouge. Hmmm.
Must get me one of those. Next on the shopping list, I reckon.

[artme]

On the subject of detail gouges, I have several that seem to have a flute somewhere between my Hamlet spindle gouge an bowl gouge when it comes to flute depth. Is this something others notice?

Also, what shape do you sharpen your detail gouges to?

Using a Heligrind I get what I consider to be a far too pointy profile.

When Ern was here last week he said that this is much the same shape as Richard Raffan uses. I'm no Richard Raffan and I prefer my profile to be more rounded.

How about others?

[Hermit]

On the subject of detail gouges, I have several that seem to have a flute somewhere between my Hamlet spindle gouge an bowl gouge when it comes to flute depth. Is this something others notice?

Also, what shape do you sharpen your detail gouges to?

Using a Heligrind I get what I consider to be a far too pointy profile.

When Ern was here last week he said that this is much the same shape as Richard Raffan uses. I'm no Richard Raffan and I prefer my profile to be more rounded.

How about others?

And while we're on detail gouges - I've noticed in my reading that many people, mostly overseas, use the terms 'spindle gouge' and 'detail gouge' interchangeably.
Can anyone define the difference between the two, in flute depth, bevel angle and profile? (I assume they're not talking about a traditional grind spindle gouge.)

[stuffy]

And while we're on detail gouges - I've noticed in my reading that many people, mostly overseas, use the terms 'spindle gouge' and 'detail gouge' interchangeably.
Can anyone define the difference between the two, in flute depth, bevel angle and profile? (I assume they're not talking about a traditional grind spindle gouge.)

The Detail Gouge has a shallower flute and a heavier section than a spindle gouge, and is sharpened with a long fingernail grind.
While the grind is long the edge should be curved the whole way and rounded at the tip, not flat or too pointy.

:)

Steve.

[Hermit]

The Detail Gouge has a shallower flute and a heavier section than a spindle gouge, and is sharpened with a long fingernail grind.
While the grind is long the edge should be curved the whole way and rounded at the tip, not flat or too pointy.

:)

Steve.

Well-described. Thanks very much for that Steve. I thought they were different animals, but my web reading had me confused.

I don't even have a spindle gouge yet, unless you count a couple of cheap Chinese pressed steel ones, ground like roughing gouges.

[stuffy]

The best detail gouge I have used is the P&N. I use it for everything from tiny coves and beads, to hollowing end grain.

I sharpen it with a 30 degree fingernail grind with a big relief grind/secondary bevel due to its thickness, which occasionally gets in the way.

It's not cheap though so practise your sharpening on something cheaper first.

:)

[Hermit]

The best detail gouge I have used is the P&N. I use it for everything from tiny coves and beads, to hollowing end grain.

I sharpen it with a 30 degree fingernail grind with a big relief grind/secondary bevel due to its thickness, which occasionally gets in the way.

It's not cheap though so practise your sharpening on something cheaper first.

:)

I just saw a pic of a P&N detail gouge on Carroll's website. You're sure right about the shallow flute and the need for a secondary bevel. An odd shape all round.
320982

I'll buy one when I get a chance. The price is OK. The 12mm is a similar price to my 3/8" Sorby bowl gouge.
I learned to sharpen it without wasting too much metal. I'd rather spend a little extra $$$ and buy the best, even if I do have to replace them a little sooner from learning to get the shape right.
All of that's a little easier now that I have the Vicmarc fingernail jig.