Hardening blades

Hello!
A friend has asked me to sharpen his knife - a double edged dagger, mean
looking thing - on the nice bench grinder, but it turns out to really be
in need of hardening, since it doesn't keep the edge at all well.
I'm not entirely sure what kind of steel it is - I haven't ground it (to
look at the sparks) yet, but I'm wondering if it'd be better to harden
and temper it, or to case harden it. I've never case hardened anything
in my life, but from the description I read the combination of a very
hard outer skin and soft resilient innards sounds great.
But I know nothing about blades, really. I hear that the normal heat
hardening process generates long thin crystals which are good for
edge-forming. Does that mean that case hardening would be unwise? How
about a combination: harden it (to get nice crystals), sharpen it again
on a fine stone to get the edge really sharp, then case harden?
Thanks,
ABS
Reply to
Alaric B Snell
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Look at the name and country of origin stamped on the blade. If China or Pakistan appear anywhere, dont bother.
While there are a number of good daggers out there, they are expensive. A futher note..bench grinders are not made for sharpening knife blades, unless you know EXACTLY what you are doing, and have the proper wheels, etc etc. Ill not take the time to write a FAQ on the subject..but others hear will have further input.....
Gunner
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote!" -- Ben Franklin
Reply to
Gunner
Try the standard oil hardening and tempering with the blade and see if it gets better. If not, it's poor steel and the only thing possible is to try Casenite to get some carbon into the steel and thus harden it that way.
-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works evevery time it is tried!
Reply to
Bob May
Hello!
A friend has asked me to sharpen his knife - a double edged dagger, mean looking thing - on the nice bench grinder, but it turns out to really be in need of hardening, since it doesn't keep the edge at all well.
I'm not entirely sure what kind of steel it is - I haven't ground it (to look at the sparks) yet, but I'm wondering if it'd be better to harden and temper it, or to case harden it. I've never case hardened anything in my life, but from the description I read the combination of a very hard outer skin and soft resilient innards sounds great.
But I know nothing about blades, really. I hear that the normal heat hardening process generates long thin crystals which are good for edge-forming. Does that mean that case hardening would be unwise? How about a combination: harden it (to get nice crystals), sharpen it again on a fine stone to get the edge really sharp, then case harden?
Thanks,
ABS
Reply to
Alaric B Snell
Depending on its use, it might not need hardening. If it's designed for throwing -- and a double-edged dagger could well be - it should be left softer. That way when it slams into something it won't chip or crack.
Reply to
Jim K

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