This is just my observation. I have wanted to try 15° per edge but was reconciled to 17° from my Lansky with a 20° micro- bevel on the Sharpmaker. As I clamp each blade close to the spine and press down on the rod in its slot to get a consistent angle, I wondered if this positioning was giving me a more acute angle. Today I checked my PM2 and mini Cutjack (both prepped on the Lansky) with the 15° slot on the Sharpmaker and found the magic marker was removed to the apex. I know that the edge will not last as long as that from a more obtuse angle, but I'm happy to have this option.