What's called negative rake scrapers has been around a long time. I first saw it demonstrated by Ray Key in the late 1990s. He just tilted the regular scraper tool up at a 15º or so angle and went for it. His experience and skill resulted in beautiful results. I think there were some tip tools that used HSS ground cutters at that time also.
The "negative rake" is actually a tool tip grind to better facilitate shear scraping. Grinding the tip off of an expensive HSS tool always rankled me because of the waste of money. On the other hand, I don't use the big scrapers I have now anyway. The kicker about grinding the negative rake on a scraper is that the bottom of the scraper is generally flat and lays flat on the tool rest. That would be the fatal flaw to re-grinding an existing scraper.
Shear scraping needs to be far more dynamic for best results since the intended surface is curved. I make my own out of old planer knives for the cutters and regular round steel sticks with a 15" slant cut on the ends to mount the planer knife chip.
Outside curves are easily done with straight cutters, but the inside is a different story. That cutter needs to be curved.
A very, very light touch is required. The shaving produced is so fine as to be weightless if dropped in the palm of your hand.
Some photos I had handy. I hope others will share their own photos of the process.
Some of the scrapers I've made over the years. There are some tip tools in there that don't apply to this thread.
testing a different and more convenient way of shear scraping the outside of a bowl.
A shear scraped area cleaning up what was done with a bowl gouge.
Another view.
