Negative Rake Scraper

Hi Group, I just got around to building a negative rake scraper. I got a high speed tool steel blank to make it out of. I was wondering how critical the angles that are ground on it are? I was trying for 25* on top and 40* on the bottom. I ended with 21* on top and 47* on the bottom. I tried it out on a bowl that working on and it seem to work pretty good. Still need to make a handle for it though. A friend of mine has a purchased one and the angles on it appear to be the same and centered. Not the best pictures but they will give you some idea. Thanks, Jim

How does it cut?
That's really the only thing that matters. If it doesn't cut how you like, adjust the angles.

I don't believe the angles ae that critical. As Edward said if it cuts you are good. The reason some have identical angles top and bottom is so they can be used both inside and outside of a bowl. If it is a round nose scraper that is not an issue.

I have used NRS for years and prefer a more shallow and longer/deeper top angle. The important thing is to sharpen only the underside angle so that a burr gets raised on the upside. The more shallow and deeper top angle simply gives one more room to sharpen, though that usually isn’t an issue. I do agree that the angles are not critical. As an example one of my most used is a Thompson “skew” that has been reshaped to have a rounded nose, but the grind angles are still both close to 20* each.

Seems to cut just fine. I'll probably touch up the bottom just a little. I might have a minute flat spot in the curve.

James, what type of steel is that and what's the source? (If you don't mind my asking)

I actually just ordered some hss 8mm square stock from Amazon to make a bedan.

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Originally Posted by John Kananis

James, what type of steel is that and what's the source? (If you don't mind my asking)

I actually just ordered some hss 8mm square stock from Amazon to make a bedan.

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Looking for a sorce for stock to make a scraper also, is it nessery for us to spend 100.00 dollars for a scraper?

I picked the blanks up from Amazon. Jim
I'm going to use this blank for something else or maybe a smaller scraper.

https://www.amazon.com/gp/product/B0...0?ie=UTF8&th=1

This is the one I used for the scraper.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I make my own aluminum handles also. I have a HeliArc welder and I buy 1 1/4" or 1 1/2" tubing with a heavy wall and a matching inner tube. If I'm doing one for a square tool I have to get a little creative and do some filing for the inserts. I then fill them with lead shot for weight. I use this stuff for the grip.

https://www.amazon.com/gp/product/B0...TF8&th=1&psc=1

James, thanks for the links. After reading this, I was looking for flat v10 stock (I'm not an expert on hss by any stretch) thinking it would give the most durable edge but can't seem to find it without ordering way too much. I hope you're scraper works out well for you.

I did the initial shaping with a 4 1/2" grinder with a HF 1/16" cutoff wheel, then my 2" x 42" Craftsman belt sander. Finished the final grinds with my 800 grit and 1000 grit CBN wheels. Jim

The link below is a good source of information

https://www.woodworkersemporium.com/...ion-Manual.pdf