This subject is going on in another thread as well, I will try to answer what I can.
Mike Nathal wrote on Jun 10
th, 2019 at 5:24pm:
I can't reproduce it, but there is a video out there where Stuart Batty explains the difference in the physics.
One point I will disagree with Mr Batty on, is that you need a burr on a NRS, you do not.
This is a provable fact not simply my opinion. The other thing is that Mr Batty has decided what angles should be used to be considered to be classified as a positive and negative rake scraper.
In the diagram I posted the included angle of the standard scraper would be too great to be considered a NRS by Mr Batty, even though it is clearly cutting in a negative rake angle.
People have been using everything from a piece stone, to a broken piece of glass to scrape wood for thousands of years without a burr.
Look at a scraping plane which can be used with or without a burr or the scrapers recently discussed Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to
or
. These do not have a burr
by design and are used at a negative rake angle. As mentioned in the other thread there are NRS inserts for replaceable tip tools like Easy Wood Tools, these are carbide and do not have a burr.
I don't intend to start an argument but the physics (geometry) of Standard (positive rake) and Negative rake scrapers is clearly visible in the diagram I posted.
Mike Nathal wrote on Jun 10
th, 2019 at 5:24pm:
One thing I don't see mentioned very often is that a NRS allows me to get smooth, flowing curves on a vase shape much easier than other tools. BY being so easy to use, I can concentrate on the shape more than tool presentation.
This is what I have been trying to convey.
A NRS is
by design less aggressive, which in turn lends itself to be easier to control.
I want to be clear, a NRS
can have a burr, if there is a burr, it is usually just an artifact created by the grinding/sharpening process. Not a work hardened or burnished burr like you would find on a standard scraper.