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His looks like an equilateral triangle.
Gary
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(06-08-2019, 12:34 PM)Gary G™ Wrote: His looks like an equilateral triangle.
He says it is; "... 3, 60* angles." My point is that even if it wasn't, the tool would still be parallel to the grinder's base so the ground angle would not change. In order to accomplish that, the angle of the tool to the grinding wheel must change. In other words; the tool's handle must be raised or lowered each time it's rotated.
Personally, by working through this thought process, I think it would be much easier to start with a 2" triangular prism with the correct size hole (like the jig in the video). Set the grinder's tool rest and create the medium angle with the jig. Bevel the front on the next side of the jig just enough to create the steepest angle. Bevel the back on the last side of the jig to create the shallowest angle. I'd just creep up on the bevels using a belt or disk sander. When I got it to my satisfaction, I could just measure how much I took off to easily make many more with different size holes.
Sign at N.E. Vocational School Cabinetmaking Shop 1976, "Free knowledge given daily... Bring your own container"