Thread: shear scraper

Frank - rather than getting into wordsmithing a definition for shear scraping, let's adopt some existing descriptions from established sources. The following all describe what I understand to be shear scraping:

Richard Raffan, here.
This link has lots of good descriptions and tool info by Steven Russell
A collection of descriptions (by the Sydney Woodturners), here

Hope that helps

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Neil,

I've been playing with scrapers for some time. Well, a long time.

If I do an Ellsworth sheer scraping cut with the tool layed over on its back, I still get ridges. Tiny ones that sandpaper removes almost immediately. But not a great off-the-tool finish.

I much prefer using a scraper flat on the tool rest (no burr, Tormek sharp).

Worked OK at Proserpine on Boree which is fairly hard. (Ken W. insisted I use his radical 45 degree bevel scraper, knowing full well that I was scared of it. stood up for me, until Ken explained his reasoning..... Buggers. )

Or am I doing something wrong?

I know Ellsworth is a fine turner and makes do with just one chisel with his grind. But why bother?

Originally Posted by NeilS

Frank - rather than getting into wordsmithing a definition for shear scraping, let's adopt some existing descriptions from established sources. The following all describe what I understand to be shear scraping:

Richard Raffan, here.
This link has lots of good descriptions and tool info by Steven Russell
A collection of descriptions (by the Sydney Woodturners), here

Hope that helps

.....

Sorry for my insistence on wordsmithing, Neil (professional syndrome, I am afraid) but you are nailing the problem with your own words. In my presumption, I want to find, or create if there is none, a definition. What the literature offers, as you say yourself, is descriptions. I want to explain why, not only how, it works. Richard Raffan's description and photo actually are the best so far to support my definition: he mentions pulling the upper surface of the blade towards the surface of the wood. The other descriptions are not very useful, I had already googled them in my earlier research, but none provides any contrary evidence.

Are you trying to tell me that you do not trust your power of observation?
BTW, seems that all the other gurus do not trust theirs either...

A few thoughts on what you have said, Jeff.

Originally Posted by jefferson

If I do an Ellsworth sheer scraping cut with the tool layed over on its back, I still get ridges. Tiny ones that sandpaper removes almost immediately. But not a great off-the-tool finish.

I'm not quite sure that I can quite envisage the cut that you are using there Jeff, when you say that the tool is 'over on its back'.

For a standard scraping cut I would expect the gouge to be on its side (tool handle almost horizontal and flute axis just above horizontal) with the lower wing doing the work. For a shear scraping cut I would expect it to be still on its side (flute axis just above horizontal) but with the handle dropped.

But, if you were to drop the handle even further (almost horizontal) and rotate the tool so that the bevel is rubbing and the wing cutting then, IMO, that is more of a shear cut than a shear scrape. A useful fine finishing cut but it will still leave some fine cutting ridges.

I use the latter to tidy up rough turned green blanks before putting them aside to season, but prefer to use dedicated scrapers before final sanding.

There is no reason why an Ellsworth gouge couldn't be used to shear scrape as well as any scraper (other than into tight corners and coves), BUT the downside is that they have to be re-jigged every time they have to be re-honed, whereas most standard scrapers can be quickly freehanded on a rest.

I much prefer using a scraper flat on the tool rest (no burr, Tormek sharp).

If it's working for you then stick with it, at least for now.

Worked OK at Proserpine on Boree which is fairly hard. (Ken W. insisted I use his radical 45 degree bevel scraper, knowing full well that I was scared of it. stood up for me, until Ken explained his reasoning..... Buggers. )

You're welcome to have a go at my 15° scrapers (more knives than a scraper) any time you like.... .

Or am I doing something wrong?

No, nothing wrong! Just give shear scraping a go at some stage if you haven't done so already. Shear scraping is less inclined to cause end-grain tear out, but is also less inclined to 'iron out' any irregularities in the profile.

I know Ellsworth is a fine turner and makes do with just one chisel with his grind. But why bother?

I can understand that some turners can get to a point where they prefer to make do with the tool that is in their hands rather than reaching for another tool. They will have the job done with what is in their hands before the other tool is checked for sharpness and the tool rest adjusted for it. Keep in mind that they will have proficiency with the various other tools and know how to get a 'similar' result from the tool already in their hands. While other turners have a specialist tool for every task and just love using lots of them....

Originally Posted by Frank&Earnest

Are you trying to tell me that you do not trust your power of observation?

I must admit, that by the time I'm down to the scraping my attention is fully on the form and not the technique. More often than not, my eye is on the form on the opposite side of the pieces to where the tool is working. The visual, rather than the verbal, area of my brain is what is being fully exercised.

You are not likely to go too far wrong, Frank, if you adopt the Raffan description/definition. He has very few peers in combining both high level proficiency and very clear writing skills.

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FWIW this thread has had me looking closely at where the tear-out occurs on bowl outsides. On two species examined, it's not the end grain - it's close to it after the long grain passes.

This is clearly the point at which the fibres have least support from their fellows further up the surface. Put the tool edge at a shear scraping angle and support is increased by the good offices of fibres closer to the headstock on the same plane.

This is why some turners use eg. a forged spindle gouge with the cutting edge around vertical. The downside is prob. slightly messier long grain but this will quickly scrape or sand clean.

Originally Posted by NeilS

A few thoughts on what you have said, Jeff.

Neil, I do appreciate the long advice / lesson. I type faster than most (the opposite for me when turning). 60 words a minute isn't too bad for a 50 year old???? So I do appreciate your efforts. And all the encouragement given here FOC.

I think I am doing the sheer scraping right. Or so tells me. When I say the tool is "on its back", I probably should have described it as you did. Handle down, flute closed, almost to the point of touching both sides of the tool. Almost. Safe apparently.

As the Ellsworth DVD shows, you can cut up or downhill as the cut is so fine. Dunno whether he's tried it on Boree though.

As for your 15 degree scrapers...... Politely, stick it, Neil. Maybe in 5 years time..... I've got a Ken W 45 degree one sitting out in the shed and I haven't put in anywhere near wood.....

I truly don't know what all this fuss is about re: time and using only one tool. I wander around the shed at my leisure - no production turning pressure - and lope over to the Tormek and sharpen a chisel (10 or more steps, not the recommended 5). For me, that's what it's all about. Turning time should not be about the money - unless, of course, you need it.

I haven't got my turning area ideal, nor the other parts of the shed either for that matter. Plenty of room for another lathe or two (still tossing up between a VL200 short bed and a "modified" shorter-bed 750 Stubby - Jim C. HELP!!!)

Thanks, again, Neil. Most, if not all, of the Mexicans reckon you give great advice.

Originally Posted by rsser

FWIW this thread has had me looking closely at where the tear-out occurs on bowl outsides. On two species examined, it's not the end grain - it's close to it after the long grain passes.

Agreed, Ern, 'end-grain' was just my shorthand way of saying the tear-out prone area. In my experience it's the transition area just after the end grain begins to become long grain that is the prone area. As you say, this is where the fibres are least supported.

Originally Posted by jefferson

I type faster than most (the opposite for me when turning). 60 words a minute isn't too bad for a 50 year old????

Can't even think that quickly, so the two finger hunt and peck is just about right for me!

I think I am doing the sheer scraping right. Or so tells me. When I say the tool is "on its back", I probably should have described it as you did. Handle down, flute closed, almost to the point of touching both sides of the tool. Almost. Safe apparently.

That's it.

As for your 15 degree scrapers...... Politely, stick it, Neil.

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I truly don't know what all this fuss is about re: time and using only one tool. I wander around the shed at my leisure - no production turning pressure - and lope over to the Tormek and sharpen a chisel (10 or more steps, not the recommended 5). For me, that's what it's all about. Turning time should not be about the money - unless, of course, you need it.

The gentleman turner! Not to be scoffed at, Darwin was a gentleman scientist and he more than made his mark on science.

Thanks, again, Neil.

Your welcome

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