shear scraper

Normally, it's the same thing but just presented to the wood at an angle (up on one edge of the tool to whatever degree gets the best cut) and is used in a pulling rather than a pushing stroke. You can get some really nice cuts this way.

Abnormally, I'm developing a set of small scrapers that are already shaped / ground into a shear scraping position. All you have to do is present the tool flat on the toolrest and at a straight, horizontal angle (making it easy to control and easy to get a clean cut especially when you can't see the edge as inside a hollowform) in order to get a shearing cut. While I've not seen such a tool before, especially in a smaller size, I don't doubt somebody has already done it and it's in a catalog somewhere.

- Andrew

Reyd A shear scraper is used at a forty five degree angle to the rotation of the work and typically uses a finer burr than a regular scraper. I made a couple based on idea on one of John Jordan's videos and I am extremely pleased with the results. I should have made a set long ago.

ok. got any pictures/ measurements of the bevel etc.?

Of the tools I mentioned I was developing? Not a chance.

- Andrew

is it I can't see it because its not developed that far, or because you are going to sell them, and don't want to let people make them first?:P

-------- SNIP -------

--------------------------------------- This sounds like some of the profiles that my dad ground on some of his metal lathe tools. He was a machinist for Air Force aircraft during WWII. I've used some of them in an Oland type holder. Work well even after 50 + years.

Ken Moon Webbervile, TX

Would such a profile work well on turning metal? I have absolutely no experience with metal lathes other than playing in a big old machine shop when I was little. Saw a bunch of them and played all over the big ones but never used one.

I'm trying to get the aggressiveness of these profiles down a bit. I've gone through a bunch of hollow vessel sides lately!

- Andrew

--------------------------------------- Most of the cuts on metal lathes are scraper cuts or "pointed" cuts. To remove a good bit of material, you can advance the pointed tool bit into the stock and make a lot of small spiral grooves and then finish it off with a tool bit like a rounded scraper. Remember, the tool bits are fed along the ways via a gear driven screw, so think of it as using a 1/4" spindle gouge for roughing, then cleaning up with a rounded scraper

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------------------------------------------ If you're going thru a LOT of hollow forms, you may want to think about a laser thickness set up. (Unless there's a good market in your area for funnels)

Ken Moon

OK. But I'm wondering how having a shear scraping profile would work cutting metal instead of wood. Is it really going to give that much better a surface or ease of cutting or any other benefit? I'm just curious.

These are hollowforms and not bowls so they don't work well as funnels either. A laser caliper system wouldn't work on these particular hollowers. They're far too small to attach anything to them. If these work out and I make larger ones then that's a thought though. And the laser would actually work on these better than regular scrapers (if using those in a shear scraping technique) because these are designed to be used "straight" on the toolrest and not be rotated around thereby messing up the laser pointing.

- Andrew

Ken, roughing with a 1/4 in. gouge and cleaning up with a round scraper is a good analogy to remember. Thanks.

*********************************************** Here's some tiresome musings about cutting metal (or dry pecan 'G') and wood for newbies whose only escape or defense is to plonk. It's not space science, not even Cutting Theory,101. *********************************************** All cutting edge tools separate material by wedging. They 'wedge' almost entirely according to two factors:

1. the angle of their edge (cutting angle) 2. how they are held and put to the work. Their shape, the materal they are made of and the material being cut are important, but secondary. Ex; a sharp knife made of hard steel won't cut a soft nail. A cold chisel made of much softer steel will. (just maybe, when the burr has gone, cheap scrapers are ok )

********************************************** In general, the tool edge is forced into a metal workpiece. Then the tool is wedged until the metal's shearing force is exceeded. Microscopic but discrete chips separate from the work, and the following bevel's high heat and compression forms them into long curls. (swarf) *********************************************** Cutting wood has some 'sames' and some 'differences' from cutting metal.

When cutting metal, both the work and the tool are held rigidly, and the tool's wedging angle is large and its force is huge. With wood, the tool is loosely hand held and the wedge is narrow and not forced.

When slicing wood along the grain the tool edge momentarily cuts an opening then it is replaced by the wedge and no longer touches the wood. When slicing across wood 'grain', tiny wood chips are sheared off by the wedge, and if they are strong and fuse together, those long 'show off' ribbons are formed.

*********************************************** This mess is probably a boring waste of bandwidth for the majority of you who have long since intuited it from splitting firewood, peeling cane or whittling sticks. Just in case someone missed out on that fine education, I won't erase it, but I do invite the inevitable differing opinions. :) Arch

Fortiter,

It would give a very smooth finish, but it's only a finishing tool--you can't take very deep cuts. Also, it would be more likely to chatter than the standard point-cutting tool because of the wider cut. So no, an angled shear cutter on metal won't make the cutting any easier--it would take more force because the chip would be wider, and that's one of the main causes of chatter.

Ken Grunke

Reyd Dorakeen wrote in news:BC1DE534.92F% snipped-for-privacy@shaw.ca:

Reyd, if you go to:

and look under the 2002 tab, about 2/3 of the way down the page I have some photos of a shear scraper/cutter that I devised and use with great success. It's basically a cutter made of HS steel canted 45 degrees at the end of a solid shaft. Take a look.

how do you use it? , you can just hold it horizontal can you, with that bolt on the end?

sorry,Can't*

Reyd, it is not as much a sheer "scraper" as it is a shear cutter. It is already mounted on the shaft at a 45 to 50 degree bevel, so all you need to do is take it straight into the bowl or form and smooth down the sides. It is not for use on the outside, although I imagine it could be used there. No point to it, really. I devised this tool for the final smoothing on the inside of deep vases.

It is held horizontal, with the cutter making contact at the axis of the piece, like this ==============/

Herm

Reyd Dorakeen wrote in news:BC24A3DA.3755% snipped-for-privacy@shaw.ca:

Now i feel even dumber, but isbnt the blade at a right angle to the shaft?, so the cutter on the end would only rub on the side? I know there must be some answere, but I'm confused.

in article Xns946DC34CD618Bsamsmcom@24.71.223.159, Herman de Vries at herm@REMOVETHIS_hdv.net wrote on 1/11/04 5:11 PM:

Reyd, The cutter is attached flat against the end of the tool shaft, but the end of the tool shaft is NOT perpendicular to the axis of the shaft. The shaft is cut at the desired angle that is deemed correct for the cut desired _____________________ ____________________/ // : Something like this , withthe single slash being the end of the shaft, and the double slash being the attached cutter. Does this help visualize it?

Ken Moon Webberville, TX ______________________________

Reyd, if you take a look at the picture, can you see that the cutter is canted at 50 degrees? Looking straight down the shaft from the handle, the cutter protrudes to the left of the shaft, and bears against the inside left wall of the vase. The cutting edge faces the user and the bevel is to the bottom of the vase. When getting used to the tool, start it with the blade facing downward and just rotate the tool until the sharp edge starts to cut.

The angle of the bevel is the same angle as a regular scraper, and the cutting edge does not have a burr on it. It is a slicing tool, and works best with a light cut, reaching into the vase and pulling it toward you. If you want to bear down, especially in wet wood, you can take out a lot of material quite quickly. The shavings are very thin, very fine ribbons. The tool does not get big catches because it will release from the wood very quickly if it digs in. It will take tiny little grabs, which is why you should take a light cut to finish. On end grain, you cannot cut uphill into the grain without tearing out. Downhill, it works like a dream.

Hope this all helps. As far as I know I created this tool. I haven't seen it anywhere else, and I made this about four or five years ago.

Herm

Reyd Dorakeen wrote in news:BC27391C.3DB8% snipped-for-privacy@shaw.ca:

I think I see, lee valley had some for sale, and they had some other pictures that helped.

in article Xns946EE00025E07samsmcom@24.71.223.159, Herman de Vries at herm@REMOVETHIS_hdv.net wrote on 1/12/04 8:01 PM: