jUST 180 WET AND DRY , ON A STICK , SHOULD TAKE A FEW THOU. OF IN NO TIME . oops
glue sandpaper on . Use as above or lay over bench edge . Mark a datum on the flange ( marker pen . ) count & rotate or suchlike . a m.m. you use a FILE .
Only Dont be cack handed . a 10 inch min , say 1 in x 3/8 hardwood with sandpaper folded , knife cut along with straightede ( rear face ! ) glued clamped .
a proper one not junk .