Steve, When a chisel is sharpened by first flattening the back (usually only once), the chisel's flat side can register against the wall of a mortice/tenon and you can achieve a straight cut. It also helps when paring to produce straight slices, like when making shoulder cuts. As far as the bevel...when you look at the sharpened cutting edge under a microscope, it becomes evident. Magnified... the scratch marks look wavy and corrugated. The finer the steel is abraded at the cutting edge, the easier and better it will perform. This is even more evident when paring across soft wood fibers like pine...where the fibers alternate from grain to grain. If a chisel is honed to 8000 plus grit, then stropped 50 to 100 times, the chisel is much sharper than your barbers best straight razor's edge. The same thing applies to hand plane irons sharpened this way, and will slice curls even on end grain. They also plane with less chatter.
On another note: Bench planes generally have longer chisel irons, and they make it easier to aim the chisel in the right direction because of that...Kind of like aiming a rifle versus a pistol.
Last edited by gmercer_48083; 02-18-2019 at 04:45 PM.