Quote Originally Posted by JohnC Lucas View Post
One other advantage of the negative rake scraper is it applies almost no force against the wood so you get less chatter than you do with a regular scraper. This is especially true on thin platters with wings such as natural edge bowls. I used to think that holding a scraper handle up high was the same thing as a negative rake scraper if they both had the same included angle to the edge. It's not. My older tear drop scrapers were ground about 75 degrees. So flipping them over does produce a negative rake but it still works like holding a handle high on a regular scraper. Sharpening a scraper to a more acute angle like 45 degrees and giving it a negative rake on top is a much more controllable tool and leaves a fantastic finish.
I think holding the handle high is equivalent to the NRS in the geometry of the edge relative to the wood (if the included angle of the tool is identical) but not in the presentation and the amount of control you get by holding the tool horizontal and flat against the rest. With the handle high and the edge down it seems the wood would more easily deflect the tool downwards and not make as even a surface.

Funny thing about these scrapers today - yesterday I read from a woodturning book written by F.Pain in 1957. The guy showed how he ground curved edge scrapers with profiles that look very much "Rudy Lopez's" grind - Pain ground them from old files with a sloped top similar to negative rake scrapers but he doesn't call them that. He said they worked better with this grind but didn't attribute it to the grind angle but to the idea that he was grinding down into softer steel in the middle of the file. He raised a burr with a hardened rod.

Another thing he recommended 61 years ago - "Small flexible hand card scrapers shaped with a curved end are extremely useful for troublesome places." Hey, I like that idea.

JKJ