OK, the idea of a cutting action is to reduce friction to increase cutting
efficiency, but I've yet to see any form of edge tool, much less an
arbitrary orientation material that cuts with zero friction. There may be
some super science going on with things like lasers, magnetics and possibly
even superconductors, but I'm pretty sure you won't find any of those in my
shop, other than the laser in my compound miter saw, and it doesn't do the
cutting, just the pointing.
I second that. 25 degrees then hone 1-2 degrees 26 - 27 degrees. Hollow
grinding will make your chisels weak though. NO HAMMERS on them. Just wooden
mallets to TAP them home. DON'T hollow grind Japanese Chisels, EVER ! Too
brittle for that, they chip bad.
Try 20 degrees for paring chisels. I would use a 5x11/2 or or 2 inch SLOW
wet wheel and jig. Or use a lot of water to grind VERY slow, then hone up to
8000 grit water stone. I use up to 4000 grit. My chisels are so sharp that I
shave my arm and the hair won't grow back for 3-4 weeks afterword.
Be steady and consistant with your angles.
JIGS MAN, JIGS !
My Tormek hollow grinds everything, chisels, plane blades, whatever. My
edges last a long time. I used to scary sharp. I have a full set of
waterstones, and know how to use them. Heck, my mortice chisels are all
done on waterstones. But the Tormek, with it's jigs and simple setup, gives
great results in very little time, and I usually resharpen because I feel
guilty, not because the edges are actually dull. They seem to last just
OBTW, I don't have any laminated blades, and I agree that I would not hollow
grind a laminated blade.
But the hollow grind on a 10 in. wheel can be honed out too fast for
me.Krenov School taught us to use a hand cranked 5 inch grinder to grind our
chisels and irons.
Good luck finding a hand cranker though.
Good luck finding a hand cranker though.
Hell, I see them at flea markets all the time.
I have had good luck grinding on a belt sander with about 150 grit.
Good luck with initial flattening on the B/S too.
"Honed out too fast." Honestly, I don't even know what that means. At
90rpm, even graded to 220 grit, it won't remove material fast, and with the
water bath, the irons don't even get warm. The key to the Tormek's speed is
once the irons have already been done. Subsequent sharpenings need to
remove nearly no material, so it goes very fast.
You talk about the weakness of a hollow grind. Well on a 5" wheel, you will
get a much weaker edge than a 10" wheel gives. The larger the wheel, the
flatter the bevel.
*******I see your point there, as there will be more contour, with less meat
behind the cutting edge,**********
<<<<<<<But the hollow grind on a 10 in. wheel can be honed out too fast for
<<<"Honed out too fast." Honestly, I don't even know what that means. At
<<<<90rpm, even graded to 220 grit, it won't remove material fast, and with
<<<<<<<<<<<<<water bath, the irons don't even get warm.
*******I think He means after you hollow grind on the 10" wheel, It will
be closer to a flat bevel,(less contour) and when you then hone on a bench
stone, the "hollow grind" will be removed sooner.***
For general woodworking, you'd grind to nominally 25 deg, then hone a
secondary bevel at 30 deg. For a fine bevelled paring chisel, you'd drop
these angles by 5 deg. For a heavy duty sash or mortice chisel, you'd up
them by 5 deg.
However, at the end of the day, these figures are nominal. Most
experienced woodworkers don't use a honing guide - they lay the chisel on
the stone on its grinding bevel, then lift it by a few degrees to commence
honing. I couldn't honestly tell you what my ultimate honing angle is -
it's all done by feel, so it may be a couple of degrees either way from the
recommended norms. Whatever you find that works for you.
It's worth while, when you start breaking in a new chisel, to hone the back
it completely flat -simply lay it flat on your stone, then work away until
the first inch or so at the business end is a uniform shade. For ultimate
sharpness, you'd really want a mirror finish (on a very fine stone) on the
back, but for general use, a uniform grey colour is fine.
Then when you hone the edge, you work away until when you run your thumb
across the back of the edge (not along it!). you feel a raised burr. This
means that you've honed the edge so fine that it's started to turn over
under the your honing pressure.. Stop honing the bevel at this stage, then
turn the chisel over flat on its back and give it a few more strokes flat on
the stone to turn this burr (sometimes called the "roafe" or the "wire
edge") back again. Then you can either strop it a few times on your palm or
a leather strop, or gently draw it edgewise through a piece of wood to break
off the burr and leave a clean sharp edge.
Beware when you're grinding on a high speed grinder - you need to keep the
edge as cool as possible at all times, which means dunking it frequently.
Don't let it get so hot that it starts to blue. A stone which runs at low
speed in a water bath is much better, if you have access to one.
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