I love the way this forum just occasionally throws up a thread which gets my brain cell excited and leads me to look closer at a subject that I had previously just taken for granted. This thread is a case in point and here are my morning's conclusions.....
My negrake scrapers are ground with twin bevels ,each at 40*. The tools business end looks rather like a blunted skew. This means that the burr, which is going to do the cutting for us, is thrown up at the same angle and is, in fact, forward of the apparent cutting edge so it is almost immaterial what angle you present the tool to the workpiece. It also carries the added advantage that one tool can do the work of two 'handed' shapes, it will cut either left or right according to which bevel was last ground.
A trad scraper, on the other hand, is likely to be ground much closer to a right angle so the burr will face upward. To obtain a similar cut to the horizontally presented negrake the handle will be up amongst the the rafters or the cutting edge well below the works centreline.
So, in Brian's world anyway, the 'big boy/little boy' theory does, in fact, hold water!
Now that's what I call scientific ......
Brian