(03-07-2020, 11:29 AM)Jan Wrote: I have measured the sharpened bevel angle with my laser goniometer and to my surprise the laser reflection was not 15⁰ but in a band between 10 and 12⁰. My preliminary explanation is that the when the edge displaces the belt from its straight path it starts to wrap the edge which lowers the bevel angle. The grind is no more flat but convex (sabre).
I have not really thought about it but how does a laser goniometer read on a convex, even if only slightly convex, surface? If it was reflecting off a perfect sphere for example, would not the angle reading vary greatly depending on where it beam hit the sphere?
Also, was the blade you measured flat or tapered? Of course, a tapered blade placed flat on a 15° surface would not produce a 15° bevel due to the angle of the taper of the blade. The weird thing is that I think that would increase bevel angle as opposed to decreasing it.
What is the large orange wheel under the grinder in your first post? A roll of orange tape on a beautiful brushed aluminum spool? A grinding wheel?