welded gaurd bad idea or not

C

cjd1980

Joined
Sep 3, 2008
Messages
236
hello
I'm making a large full tang knife for a friend ;and he wants a guard welded on. I can get one of the welders from work to tig it for me before I heat treat Just not sure if this is a bad idea. I m not sure if this would weaken it or have any other negitive affect n the steel ive done it with the pommels /butt caps on a few knives and it was fine just not sure with the guard area .
thanks
chris
 
Guards are generally soldered in place on a finished blade with low temperature solder. Some large and heavy duty guards are pinned/riveted in place. Either way, a properly installed guard and handle will be rock solid.

In answer to your question - Yes, it is a bad idea.
 
I also believe it to be a bad idea. It can be done "well" but I don't believe the result is ever greater than the sum of the parts so to speak. Especially if the blade and guard are different materials. Assuming it's done correctly, every step of the way: preheat, postheat, slow cool, normalization, heat treat and quench -

-you still have the possibility of creating a weakened joint due to microfractures
-you've created that possibility at what I consider the portion of the knife that requires the greatest stability and strength as the guard/bolster area is often the fulcrum bearing the brunt of all forces being applied when the knife is used
-the gain of a welded guard (stronger than solder?) is not guaranteed, and contradictory to what the welding may do to the tang

It's simply not worth it, and is likely requested by someone who things "welding > solder" based on previous experience with completely different materials and applications.

If you are going to weld a guard, the only way I would do it is to forge weld it to the blade during the forging process, and of a similar material to the blade itself. That's the only way you will avoid (mostly, never entirely) the different coefficients of expansion and contraction that come with heat and produce microcracks in welded joints in anything but low carbon, low alloy structural steels.

Welding a guard, to me, is like looking at a stud built wall and saying, "Nails aren't good enough. They always pull out, they're soft and they bend. Screws are better." and then using some kind of threaded fastener wholly inappropriate for the task, like drywall screws, which are brittle and low strength. It seems better on the surface, screws don't pull out easily, but basing the construction of the wall on that one factor, disregarding whether pullout force will actually be placed on the wall versus shear strength and shock resistance, and risking the structural integrity of the entire house for it. True, they won't pull out, but when a few heads pop off on an extremely windy day, the house might come down like it was built of cards.

(of course today there are framing screws actually intended for this, it's just an analogy)
 
I hard soldered a guard once using brass solder and bayonets issued to the British Army during WWII had brass soldered guards. Brass solder is much stronger than low temperature silver solder and used to built expensive steel framed bikes.
 
Shing said:
I hard soldered a guard once using brass solder and bayonets issued to the British Army during WWII had brass soldered guards. Brass solder is much stronger than low temperature silver solder and used to built expensive steel framed bikes.
Click to expand...


The problem is that it would have to be done before heat treat. I've fillet brazed bicycle frames (cool process:thumbup:) but it's about 1800f iirc. Low temp solder is about 400f, so lower than tempering temp on most steels. 1800f brazing would need to then go through normalizing and thermal cycling, then heat treat. You now have a guard that would be nearly impossible to finish at the blade junction. It could be done, but it would be tedious, with no benefit over a soldered or JB welded guard.
 
I'm 99% sure I saw on Jerry Fisk's Instagram he talks about how he TIG welds a guard on his Sendero
I looked for the post and couldn't find it, Jerry posts alot.

I was actually going to try this on a laminated blade clad with mild steel, post HT
416 SS can be welded to mild steel with a certain filler rod.

Too many things to do and learn so I haven't got around to it yet,
 
Willie71 said:
The problem is that it would have to be done before heat treat. I've fillet brazed bicycle frames (cool process:thumbup:) but it's about 1800f iirc. Low temp solder is about 400f, so lower than tempering temp on most steels. 1800f brazing would need to then go through normalizing and thermal cycling, then heat treat. You now have a guard that would be nearly impossible to finish at the blade junction. It could be done, but it would be tedious, with no benefit over a soldered or JB welded guard.
Click to expand...

I brazed the guard as part of the heat treatment process, I used D2 for both the guard and blade. The late John Nelson Cooper patented a method to braze guard on his knives. https://en.wikipedia.org/wiki/John_Nelson_Cooper
 
I tig bolsters onto my frame handles whatever the materials.
 
Shing said:
I brazed the guard as part of the heat treatment process, I used D2 for both the guard and blade. The late John Nelson Cooper patented a method to braze guard on his knives. https://en.wikipedia.org/wiki/John_Nelson_Cooper
Click to expand...

That is an interesting patent he filed. Here are the details on his second patent which was just an "improvement" on the first: https://goo.gl/5ycSbl

Ya'll should look at his drawings and explanation of what he's doing and how much better it is than "normal" methods of knife making.

Ken H>
 
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