This is a side view showing how a negative rake scraper is ground. You will see these in the catalogs as hardwood or ivory scrapers. Batty actually grinds the longer bevel on the top. That way you only have grind the bottom until you get near the top. The way it is ground in the picture you have to grind the top and the bottom. I can't remember if the angles are critical, I don't think they are.
Batty says on his site about 60 degrees is the best.
I believe that means the included angle--but could be wrong. That would be a much sharper angle than is pictured here, which is about 100 degrees.
Or he means the angle of each bevel from the blade, then this would be in the ballpark.
Thanks for posting these pics Keith, they really help.
Supposedly, it should cut cleaner than a standard scraper and is less likely to catch. I don't know how it will work with all woods. I haven't tried it in my shop yet. Stuart uses it to clean up the wings on his pieces. Most of his work is done in Cocobolo and Australian burls. Hard, dense woods. He also has a Neg. rake tool with a rounded end and a long grind down the side for doing the inside of his winged bowls. It is similar in shape to Raffans box scraper but the cutting edge goes farther down the side.