1084 quenching, just the blade?

C

chriswillman

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May 1, 2011
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Hey guy's I was wondering if it is okay with 1084 to quench just the blade, and leave the handle area softer? I just got 3 gallons of canola oil in a bucket, and tomorrow I am planning on finally hardening this 1084 knife in some 130 degree canola oil. It's my first knife, so I'm not going to be too "picky". This knife is only 5 3/4 inches long and 3/16 inches thick. I am wondering about the grind. I hope it's not too thick. Oh well, I have plenty more 3/16, and 1/8 1084 from Aldo Bruno to work on after I get this one finished. I am mostly asking for future reference, but can I quench just the blade of 1084 in 130 degree canola for hardening?
 
It is usually better to harden the entire blade, including the tang, when quenching.
Drill all holes prior to the quench. You can draw the spine back to a much lower temper than the blade after quench.
 
I have a few ideas of why it might be better to harden the entire knife rather than just the blade but I would like to hear a knowledgeable explanation. I've only hardened my blades because my "forge" is too small to fit the entire blade and tang.

- Paul Meske
 
A simple reason is that a partial quench creates a barier zone with two different structures. A full quench has all one structure. Would you rather walk across a foot bridge with a single oak board or one jointed with pine for half and oak for the other half?
 
If you aren't going to be too "picky",... yeah I think it would be O.K.

... just be sure and quench through the blade to handle transition area.
 
Does the same principle apply to an edge quench? Is it better to quench the entire blank and then draw back the spine and tang than to just quench the edge?
 
I think that generally the same principles apply, although the scenarios are slightly different, and there are quite a few variables to consider,... not the least of which are the intended purpose/purposes of the knife and the short term and/or long term goals of the maker.
 
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Edge quench and clay coated spines are for asthetic reasons. Metallurgically, a full quench is better. That does not mean that an edge quench or a blade with the tang left out of the oil will make a poor or inferior knife. If the question is "will it work" ,the answer is "Yes." If the question is which is the better way, then a full quench is the answer.
 
Good points Stacy, but the question wasn't which would be better from a theoretical or metallurgically idealistic standpoint,… just if it would be "okay" (or will it work). But again, it needs to be hardened through the transition area. The handle will give some extra strength in the back section of the knife.

Given that the blade is 3/16ths thick along the back and only 5-3/4 long, the chances of lack of strength or failure from lateral stress are extremely narrow, if not completely out of the realm of normal non-abusive “knife usage“. The thickness of the stock is probably even an overkill.
 
The first lesson I learned about hardened tangs came from Bill Moran and it was simple and to the point. "Never harden a tang".
I have followed is words totally, naturally I had to experiment to prove to myself why. Tangs have stress raisers, and are generally of smaller dimension than the rest of the blade, holes in them are stress raisers. I have a number of "abused" knives, both factory and custom with broken tangs that had been hardened.
 
Ed, theoretically a plunge grind is also a stress riser,... but I've never seen a blade snap or take a set right at that point or ever even heard of one. However, if you set out to snap it or bend it at that point, I'm sure you could with a vise and cheater bar.

What ever works in the real world I guess...

I'd just say,... don't "abuse" your knives and don't encourage knife abuse. If you need a pry bar, baton etc., out in the field use your knife to make one out of a stick. etc., etc., etc.
 
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Tia: Good point! If I cut plunge grind sharp it will act as a stress raiser, however if we blend them into the blade (called a fillet by the machinists) and put a slight curve in it we can reduce the probability of the plunge grind being a stress raiser in a convex blade. I have never had blade fracture due to a blended plunge grind.
 
Good point Ed. I customarily do a very gradual radius in that area to help distribute the stress more evenly. I try to avoid a sharp radius or 90 degree angle plunge. Recently I have also been eliminating the plunge altogether on some of my knives.
 
One aspect that should be mentioned is that the little nick that many put in their blades in front of the ricasso is also a significant stress raiser.
 
Tai Goo said:
I'd just say,... don't "abuse" your knives and don't encourage knife abuse. If you need a pry bar, baton etc., out in the field use your knife to make one out of a stick. etc., etc., etc.
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Unless of course you don't have the materials or you are incapacitated enough not to reach them. Sometimes, the best(only) option is your knife. Ever try to dig in frozen ground or chip through a foot of ice with a stick or rock.... let alone, being tired sick or wet? Just thoughts. As much as I tend to disagree with Ed's metallurgical standpoint, I respect his dedication to making the best, toughest knife he can and being totally upfront about his processes. One knife, One life.... Ed, gets it.;)

Ed Fowler said:
Tia: Good point! If I cut plunge grind sharp it will act as a stress raiser, however if we blend them into the blade (called a fillet by the machinists) and put a slight curve in it we can reduce the probability of the plunge grind being a stress raiser in a convex blade. I have never had blade fracture due to a blended plunge grind.
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It is not hard to do essentially the same thing to the tang. Blades are easy, IMO... trying to design a better knife started at the tang for me. I have almost eliminated plunges, holes and sharp corners from my bushknives. Fully hardened and tempered to suit. Knives can be prybars and still cut well with the right geometry and heat treat.

Ed Fowler said:
One aspect that should be mentioned is that the little nick that many put in their blades in front of the ricasso is also a significant stress raiser.
Click to expand...
+1:thumbup: ..... don't forget "thumb jimping" or "sawbacks" they remind me of the scoring on exacto blades to allow them to break easier!
 
Many do chamfer or c-sink tang holes as a precaution against stress risers. A well made custom knife should have no stress risers in the ricasso-tang transition, either. Provided the above conditions, I'd rather have a tang be tougher to bend through that area, indeed the spine as well along the blade length. Just my opinion, of course.

"A metallurgically idealistic standpoint!" That's great, Tai.

I'm curious though, Ed. I seem to recall reading somewhere, and maybe it was you that said it in response to a question about your handle fastening methods, that you rough up your tangs and notch them etc., to provide a hold for the epoxy. If that's the case, it sure sounds like "stress risers" to me... comments?
 
"Unless of course you don't have the materials or you are incapacitated enough not to reach them. Sometimes, the best(only) option is your knife. Ever try to dig in frozen ground or chip through a foot of ice with a stick or rock.... let alone, being tired sick or wet?" Rick

Well yeah, if you've exhausted all other options first or there is no other option or time. However, in the event of "knife abuse" you are gambling with a very valuable tool, that you might need again.

A certain amount of hypotheticals and "what ifs" are heatly, but after a point,... I think it can get a bit silly. That being said though, I don't think digging in frozen ground or chipping through a foot of ice is nessesarlily abusive, depending on the knife.


"A metallurgically idealistic standpoint!" That's great, Tai." Salem

LOL! :)
After I wrote that, I wondered if there even was such a thing...
 
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Tai Goo said:
Well yeah, if you've exhausted all other options first or there is no other option or time. However, in the event of "knife abuse" you are gambling with a very valuable tool, that you might need again.

A certain amount of hypotheticals and "what ifs" are heatly, but after a point,... I think it can get a bit silly.
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Totally agree with you, Tai.... and it would be silly to use your knife for something that could render it useless if you had options. OPTIONS OPTIONS OPTIONS are the key to survival from getting lost in the desert, to being married.:D


I requoted this bit...
"what ifs" are healthy, but after a point,... I think it can get a bit silly.
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True enough... but until we are able to nail that point it is good to throw around "what ifs".

Infact, who would have thought that using my knife to remove a fused bearing race was the most logical approach? I don't think I ever would have put that one in my "what if" list but there it is...

Rick
 
... My computer is doing some funny stuff with the text today, lines repeat, disappear, mouse not responding. That last post was way too hard. I guess it must need some sleep time... I give up.
 
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