Getting my new Robo Rest grinding platform (which I really like) brought this to my mind again. I'm sure this is clear to many of you and makes you wonder how someone who has been at this for a while can still need clarification but - here I go. When folks say they grind their tools to a certain angle I've been confused over what angle they are referring to based on how they describe it. I'm not always sure they are talking about the same angle. I've included a crude pic to clarify my question. The confusion came to mind again because the Robo Rest does not measure the grinding angle the same as my little digital angle gauge. The digital angle gauge starts at 0 deg. The Robo Rest starts at 90. So, my little digital angle gauge is measure angle A while the Robo Rest is telling me angle B. If you use a digital angle gauge to set your platform it's easy to get confused between what it says and what your metal angle finder will say when put it in the flute and the arm put against the bottom bevel. I've seen videos of guys saying "set your platform to XX deg" using a digital gauge which is different than the way I think most think of the angle they want.
So, when a turner says they grind to XX deg my assumption is they are talking about angle B in the picture. When they say the included angle like on a NR scraper is XX deg I assume they are talking about angle A, doubled of course.
Pic - handle to the right, horizontal dash line is the bottom of the flue or center of a NR scraper.
So, when a turner says they grind to XX deg my assumption is they are talking about angle B in the picture. When they say the included angle like on a NR scraper is XX deg I assume they are talking about angle A, doubled of course.
Pic - handle to the right, horizontal dash line is the bottom of the flue or center of a NR scraper.