Question about measuring the angle of a gouge grind

[Glen Blanchard]

When referencing the grind angle of a gouge, what exactly is the reference surface? Is it referenced from the bottom of the flute or from the non-working side of the gouge? I believe these are complimentary angles, the sum of which will be 90, so a 45* bevel will read 45* either way, but any other other angle will yield different measurements dictated by the surface referenced.

Hope that makes sense.

[John Keeton]

Glen, I think most use the same methodology as depicted on the diagram Doug Thompson has on his site - http://www.thompsonlathetools.com/images/extra/Sharpening.pdf

[Thom Sturgill]

Measuring from the bottom of the flute to the face gives the same angle as shown in the Thompson pdf and is often easier to measure.

[Dale Bonertz]

The simplest is to measure from the bottom of the flute and then down the nose bevel. If you are measuring from the outside of the gouge or off of the round you may get a misread if the protractor does not stay in place. Also measuring off of the flute will measure 45 degree if that is what your after but if you measure off the outside of the gouge and up the bevel it will read 135 degree. It is the same principle as measuring the inside and outside angles of a triangle using the same plane.

[David C. Roseman]

Glen, I think most use the same methodology as depicted on the diagram Doug Thompson has on his site - http://www.thompsonlathetools.com/images/extra/Sharpening.pdf

Anyone happen to know why Doug measures the scraper angle differently in his pdf than the gouge angles? He labels it 20 degrees, I would have thought 70. :confused:

David

[Reed Gray]

Scraper angles are measured both ways, and I am not sure why, but 20 degrees one way is 70 degrees the other way. I prefer the 70 here, and when trying to describe it, I say it is more 'blunt'. Stuart Batty does it a little different in that he takes into account the hollow grind from the grinding wheel. Can't remember exactly, but a 45 degree bevel with an 8 inch wheel hollow is some thing like 42 degrees. Not sure that it really makes any real difference though.

robo hippy