NRS vs Shear Scrape

[John Kananis]

Can someone take a minute to explain the difference? Aside from the grind angle and how high you hold the rear of the handle, I can't see a difference in the cutting geometry. I've watched tons of video and read an equal amount but I can't find info comparing the 2 techniques and the benefits of one over the other.

[Jason Edwards]

For me, I use negative rake scrapers on the inside of a bowl, and shear scrape the outside. I shear scrape with either a bowl gouge with handle dropped way down, or a spear pointed scraper rolled up on edge. Lately I've been using the spear scraper a lot more as I find I control the outside curve of the piece easier. Hope that helps in some small way.

[John Kananis]

Maybe I'm using the wrong term. For instance, the way Richard Raffan uses a blunt edge scraper and tilts the handle up in the back. Isn't that presenting the cutting edge the same way a nrs does and at similar geometry?

[Bill Howatt]

Although it would seem so, it appears there are differences. Have a look at: https://www.aawforum.org/community/t...of%20the%20way.

There are various things that Richard Raffan does that just don't seem to work as well for us mortal turners!

[Kevin Jenness]

Maybe I'm using the wrong term. For instance, the way Richard Raffan uses a blunt edge scraper and tilts the handle up in the back. Isn't that presenting the cutting edge the same way a nrs does and at similar geometry?

Tilting a standard scraper down does present the cutting edge to the work similar to a negative rake scraper. However, the effective angle changes depending how far the scraper is extended off the tool rest. A nrs allows for holding the tool level with a constant presentation angle. On the inside of a bowl you could run into trouble tilting a standard scraper down as you want to keep the cutting edge above center to avoid a catch.

[John Kananis]

Bill and Kevin, now it makes sense. So it's similar until it's not. Thank you for the guidance.

[Richard Coers]

In my mind a NRS is like a card scraper in furniture making and a shear scrape is more like using a hand plane that is skewed at an angle. One uses a burr, the other has an extreme shear angle.

[John Kananis]

Great analogy. Thank you for that.

In my mind a NRS is like a card scraper in furniture making and a shear scrape is more like using a hand plane that is skewed at an angle. One uses a burr, the other has an extreme shear angle.

[Don Stephan]

Cutting edge above center to avoid a catch? I always have the scraper cutting edge horizontally below the handle to avoid catches.

[Kevin Jenness]

Cutting edge above center to avoid a catch? I always have the scraper cutting edge horizontally below the handle to avoid catches.

I may be wrong but I thought it was standard practice when conventional scraping on the outside of a bowl to present the scraper level with the edge below center, on the inside above center. In either case if the edge catches it is kicked into empty space, otherwise it would dig in and cause a more serious problem. Same with a negative rake or traditional scraper.

Shear scraping is a different story.

[Reed Gray]

Well, I do have one video dedicated to shear scraping up on You Tube, and it can be done on the inside of a bowl, and that is also covered. For the difference between shear scraping and NRSs, think of speed bumps in the parking lots. If you hit the bumps straight on, it is a big bump. If you hit them at a 45 degree angle, it is a much smoother bump. So, standard scrapers and NRSs are both scrapers. You can not duplicate the NRS by using a standard scraper and raising the handle. As Ed Weber said, you get a 'raking cut'. So, if you are familiar with card scrapers, you tilt them into the direction you want to cut until they start cutting. If you tip them too much into the direction you are cutting, you can get tear out because the cutting edge is going too much over the edge, and it rakes more than it cuts. A NRS is still a scraper. Results can vary a lot between different woods, and the particular style of NRS you are using. Most seem to prefer the skew chisel style. They are a very high maintenance tool since the burr is gone in seconds. From Tom Wirsing, "if you have to push at all with the NRS, then it is dull." I prefer a 60/30 grind. My theory is that the burr needs a certain amount of metal under the burr for 'support'. When dull, I will burnish the burr down, then back up. As I said, the NRS is still a scraper, so it will pull more at the fibers as you cut when compared to a gouge, which is a shear cut/slice. For bowls, they work great for sweeping across the bottom of the bowl, but not as well when going up the sides. They don't pull on the fibers as much as the standard scrapers do, but they still pull rather than slice. Up the sides of the bowl, and this can vary hugely with different woods, you will still get some tear out. On end grain turnings, you can get glass smooth surfaces that do not need sanding. I do need to get my NRS video out....

robo hippy

[John Kananis]

Reed, thank you, that explanation helped a bunch. And I've seen the video you referenced, I'm subscribed.