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Irish Grind Advantages? (Read 190 times)
 
Don Stephan
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Irish Grind Advantages?
Apr 29th, 2022 at 5:47pm
 
Anyone with experience with an Irish grind that can explain any particular types of cuts that work well with this shape? Just curious about woodturning history.

One source I found on the Internet shows a relatively narrow primary bevel, a similarly relatively narrow more acute second bevel, and a third more acute bevel at the heel. 

Anlother source said the nose angle was about 70 degrees and the sides ground at about 30 to 40 degrees.

Another source used a Varigrind jig to create a nose angle of about 60 to 65 degrees, the wings were swept back what looked like about 1 1/2 times the bar diameter of the gouge, with a convex curve on each side of the nose, centered on the wing.  It was suggested the grind was an improvement for deeper and closed bowls over what might have been a more rounded nose and short wings.
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« Last Edit: Apr 29th, 2022 at 6:14pm by Don Stephan »  
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Ed Weber
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Wilton, California, USA
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Re: Irish Grind Advantages?
Reply #1 - Apr 29th, 2022 at 7:09pm
 
I can only speak for myself. I use a swept back wing grind that looks similar to John Jordan.
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Look at article, Side Grind Gouges

The reason I use a secondary or sometimes tertiary bevel, is simply to release the heel of the tool for the transitioning cut from side to bottom without bruising or marking the wood. This just allows for a tighter curve to be cut without touching.

I was asked once bu one of the members here what my bevel angle was, and I had to go look  Grin It was exactly the angle that works for me. Which turns out to be about 67 or 68 degrees nose angle. Which is right in the middle of what you posted.

I use a vari-grind original or II, it makes no difference to me. You can achieve the same grind with either system.

I use the wings (side grind) for shearing cuts. A high angle shear leaves me a nice finish, allowing me to begin sanding at a reasonable grit, never less that 150.

Photo 1 is a standard grind, photo 2 is a (sloppy) three bevel grind to ease off the heal.
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robo_hippy
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Re: Irish Grind Advantages?
Reply #2 - Apr 30th, 2022 at 11:24am
 
The Irish/swept back/O'Donnell/Ellsworth grind is widely used. Only real differences I have seen are nose bevel angles, from 60 to 70, and some like the wing to have a straight edge, and some prefer more of an arc like Eds in the above picture. I haven't used one in years. As far as what you can do with them, They are kind of a 'does everything' type of tool. On the outside of a bowl, you drop the handle, and present the wing to the wood for a nice high angle shearing cut. Can't do that cut on the inside of a bowl because of geometry of the bowl, and the lathe bed gets in the way. Because of the nose angle, you can make one continuous cut from rim to bottom on the inside of a bowl. A cut I don't use much, on the inside of a bowl, you cut more with the wing rather than the nose. If you come off the wing, you can get a huge catch. You can use the wing for shear scraping on the outside of the bowl. On the inside, I have seen people doing a 'shear scrape' with the gouge horizontal/flat. Personally, I think that cut is closer to being a cut similar to the NRS/negative rake scraper. There is no shear angle to it.

Now, I don't use one any more. Why? Well, I went to the 40/40 grind for the outsides of my bowls, and for the inside wall. Since it doesn't go through the transition and across the bottom of the bowl well, I now use a BOB/bottom of bowl gouge. They are ground to about 60 to 70 degrees, and generally have a little sweep to the nose, so more of a ) shape than square across the top. I feel that the specialized tools perform better than the 'does everything' tool.

robo hippy
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Ed Weber
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Re: Irish Grind Advantages?
Reply #3 - May 1st, 2022 at 1:01pm
 
robo_hippy wrote on Apr 30th, 2022 at 11:24am:
I feel that the specialized tools perform better than the 'does everything' tool.


I agree to a point.
While an Irish grind is capable of cutting an entire bowl from start to finish, it may not always be the best fit for some.
Many times, it can be more of a workflow situation. Where people find it easier to use one tool, rather than change two or three time during the turning process, whether it's the right decision or not.
It's also easier for some to concentrate on "mastering" one tool, everything from sharpening to the proper cutting angle. Having to learn a half dozen specialty tools can sometimes be intimidating.

Personally when turning a bowl, I'll usually stick to one or two tools. Most times it's two different bowl gouges with either a different size or flute shape.
If I thought a different tool would do a better job, I'd use it but a bowl gouge with swept wings and eased off heel can do just about everything I need it to do, rough, cut, hollow, scrape and shear.
That's why I use them. JMHO
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robo_hippy
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Re: Irish Grind Advantages?
Reply #4 - May 2nd, 2022 at 11:24am
 
Oh, let me see...... Big Ugly tool for all roughing. 40/40 for finish cuts on the outside, then shear scrape. Turn recess, rough with 1/4 inch 40/40, clean up with left sides NRS. Rough inside with Big Ugly, finish wall with 40/40, different shear scraper for inside wall. A bunch of different BOB tools for the transition and across the bottom. Some times shear scrape, some times NRS to smooth out the bottom and transition area.

One can never have too many tools.... End result is what matters. I would expect that if I used one gouge for an entire bowl, I would have to stop and sharpen one or more times. With current set up, I may need to sharpen once every couple of bowls. The Big Ugly can rough out maybe 10 bowls before needing to be touched up.

robo hippy
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