I've been trying to sharpen my 6" jointer blades with the the
sandpaper/scary sharp method as described here:
but for the life of me I cannot get them sharp. If anything they are duller
than they were when I started. I have a set of Hirsch chisels that I use
the same technique on and they will get sharp - very sharp. But after going
through the grits 80, 120, 220, 320, 400 the jointer blade are just plane
dull, heck the factory square edges are sharper than what I did.
I hold one blade flat along the glass with the front bevelled edge acting as
a guide for the one I am trying to sharpen. As near as I can tell the blade
stays in this position - I don't let it rotate on edge. In the article they
don't even use a guide, they just "feel the beveled surface on the paper".
I even mark the edges with a marker to make sure surface wears evenly. How
long am I supposed to stay on each grit - seconds? minutes? hours? Is it
even possible to sharpen jointer knives this way? I'm doing something wrong
I know but can't tell what.