Bill, you can get a shaped grinding stone for your hand cranked grinder. The
stone which come to a point on their face instead of a square face and use the
point back and forth to create the inside bevel then refine with stones.

Second option is the wave shaped diamond stone for sharpening gouges they make a
coarse and fine. Woodcraft carries them I think.

Lastly and quickest is a cutoff wheel in a dremel or in an (cough, Er, um...)
angle grinder held perpendicular to the desired bevel and sweep it back and
forth to create the bevel

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Brent Kinsey