This is a quote from Madsens ;
The single most important rule in sharpening chisel chain is to align the corner on your grinding wheel (or file) with the working corner on the tooth. On a perfectly sharpened tooth, all angles converge in the working corner. The drawing on the left shows you such a tooth. If the corner on the grinding wheel is not aligned in the working corner, you will create a beak -- and this is not good.
A while ago, someone misunderstood this rule and spread the word that the corner on the stone should align on the face of the cutter tooth in "both" the outside corner and the corner on the inside of the tooth. This "corner to corner" grind has been the subject of heated debate ever since.
FACT: The outside corner is the only corner that has to be aligned with the corner of the stone. Whatever happens on the inside corner doesn't matter.
Instead of worrying about the inside corner, pay attention to the angle on the outside top plate, outside side plate, and inside side plate. Make sure all these angles converge in the outside corner of each cutter tooth. Do this, and your chain will be a top performer.
Got questions or comments about sharpening square chisel saw chain? Call or stop in.
ATOPs do give you a fairly aggressive inner angle .
