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RWL
 
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Default Failure to get sharp

On Sun, 05 Oct 2003 17:30:52 GMT, Jim Wilson
wrote:

RWL wrote...

One thing that I notice is that I never get a wire edge on the
flat side when grinding or hand sharpening these. That is
probably a clue to something.


I agree. Given what follows, the most likely suspect is honing technique.
Without knowing your proficiency at honing this kind of edge, it's hard
to say, but if you don't raise a wire, you're simply not going to get a
very sharp edge.

Are you honing both sides of the edge? What is the shape of the blade? If
it's a woodworking blade like a plane iron or chisel, are you flattening
and honing the face (I.e., the back) first? What type and grit of


The blade is flat on one side and bevelled on the other to a 20
angle. Once I got it semi-sharp on the 3650 RPM grinder, I switched
to emery cloth glued to heavy glass plates - ala Scary Sharp system.
I must be doing something wrong, because it's not working for me.

I draw the blade away from the pointed edge over the emery cloth under
pressure and gently slide it forward for the next stroke maintaining
the angle the whole time - it's a broad enough bevel that it can be
felt and held on the plate. After a few minutes of this stroking, I
flip it onto its back / flat side and draw it away from the cutting
edge.

One thing I've noticed is that the emery paper gets dull pretty
quickly. I'm only using strips about 3" wide and 6-7" long.
I'm using 100, 180 400 and 600 grits.


Rough grind before heat treatment, finish grind and hone after.


Hmmm. That would be a lot more convenient because I wouldn't have to
worry about drawing the temper while grinding if I did the lions share
before hardening and tempering. I was afraid to do that because I
worried that I'd burn the edge / burn the carbon out of the steel at
the edge when heating it to red hot on the initial hardening.

Has anyone had this experience?


It used to be hard for me to get a razor-sharp edge on my plane irons and
chisels. Eventually, I just got the hang of it.


Thanks Jim. I'm strongly beginning to think I must be doing the
honing wrong.

RWL

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