Hi temp silver solder?

How do you use it on a knife? It is too low a melting point to use before heat treat, and too high a heat required to use after.

Teach me somthing.

Mike
Maker
The Loveless Connection Knives
 
Michael Lovett said:
How do you use it on a knife? It is too low a melting point to use before heat treat, and too high a heat required to use after.

Teach me somthing.

Mike
Maker
The Loveless Connection Knives
Click to expand...

i could see using it to fab a pommell nut, I usually use hard brazing rod for that.
 
I use it for tang extensions. I file a lap joint in the tang and extension, double pin, then silver braze. Very strong.
 
I use it for adding the screw onto the tang for the pommel. The temp is not high enough to re harden the tang. I have had the screw fail by Excessive tightening but never the braze.
 
You can make your own by alloying fine silver with brass. All you need is a scale, MAPP gas torch (or other suitable torch) and a crucible.

Hard- 5 parts silver to 1 part brass
Medium- 3 parts silver to 1 part brass
Easy- 2 parts silver to 1 part brass
 
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I use silver solder quite a bit for ferrules, blade collars, stone settings, mokume, soldering softer materials like copper or bronze on the end of tangs for easy peening etc. With those types of parts you don't necessarily need to worry about heat treating temps., especially if they are separate parts from the blade.

I have used "hard and medium grade" silver soldered pieces on small blades and parts prior to heat treating, but it gets tricky... On some of them I differentially harden or "heat" the blade so the part that's soldered never heat up too much. However, on some pieces I do heat the soldered area during the quenching cycle. For this I use "hard grade" which flows at a lower temp., than the heat required for quenching, but melts at a higher temp than medium or easy. I usually do this with steels that can be hardened at lower temps, 1450-1500 degrees. So, it's some tricky business with a solder that flows around 1425. However, you have to remember that each time you melt the solder the melting point of it goes up,... but you are still working with a very small margin for error.

First, the part, guard or blade collar and blade have to be clean, free from scale, oxidation etc., and fit tightly enough so that they won’t move during the soldering or if the solder does melt during the HT. Also, after the soldering, if you clean the flux (and excess solder) off first, then "oxidize the steel", the solder won’t be able to flow out because the oxidation and capillary effect prevents it even if it does melt.

Sometimes you can silver solder parts to a blade or heat treated part after the HT, simply by shielding the edge portion of the blade (or working portion of the part) with an insulating material, like KAO wool or KAO wool saturated with clay or some type of binder. Also, in some cases, you may be able to insulate the soldered part prior to HT in the same way.

If you think in terms of isolated “facts” and scientific “absolutes“, you’ll probably never try any of this… Yet, there’s usually ways to beat the odds with most things... but, it often requires a greater understanding of the materials, skill, experience, science and logic than the “scientific logical approach”. :)
 
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Hard soldering is a great skill to have as a knifemaker. I use it in my business quite a bit.
 
I’m actually working on a small trout knife today that’s going to have one or more silver soldered bolster collars… (cross my fingers). On this one I could either do the soldering before or after HT, but think I'm going to try it before.

Here’s a treble hook I recently made for a fishing lure from music wire. I did the quenching after the soldering, (with “medium grade” silver solder). The tiny ring held the third prong in place during the soldering and quenching cycle. There’s a good amount of solder holding the ring now, and all the way back along the seams between the hook shafts. You can also see a soldered collar (at the top right) on that scalpel shaft.


DSCN1635.jpg
 
Tai Goo said:
You can make your own by alloying fine silver with brass. All you need is a scale, MAPP gas torch (or other suitable torch) and a crucible.

Hard- 5 parts silver to 1 part brass
Medium- 3 parts silver to 1 part brass
Easy- 2 parts silver to 1 part brass
Click to expand...

That's great information to have Tai, thanks! What type of brass do you use?

Sometimes you can silver solder parts to a blade or heat treated part after the HT, simply by shielding the edge portion of the blade (or working portion of the part) with an insulating material, like KAO wool or KAO wool saturated with clay or some type of binder. Also, in some cases, you may be able to insulate the soldered part prior to HT in the same way.

If you think in terms of isolated “facts” and scientific “absolutes“, you’ll probably never try any of this… Yet, there’s usually ways to beat the odds with most things... but, it often requires a greater understanding of the materials, skill, experience, science and logic than the “scientific logical approach”. :)
Click to expand...

I don't want to de-rail this thread at all since there's great info going around, but I have to disagree here. "Science" (in particular thermodynamics in this case) is why all of that works and you can get away with it :)

-d
 
Yes, parts by weight. You’ll need a good scale of some sort.

I've always used yellow brass, but from what I've heard/read any brass will work. The thing is that the melting point of brass, depending on the type it is, could be either higher or lower than the silver. It can be helpful to know what the melting point is when alloying it with silver, but not absolutely necessary.

One way to go about the alloying is to cut the metal with the lowest melting point into tiny pieces, puddle the one with the highest melting point in the crucible (with flux) and slowly add the tiny pieces to it. The larger puddle with the higher melting point should rapidly absorb the tiny pieces. I think this way will work best when the silver has the highest melting point, which from my experience is usually the case. Keep in mind though, that as the silver is being alloyed the melting point will be decreasing, so keep the puddle plenty hot. The tiny pieces added shouldn't be chilling the puddle.

Another way (probably more fool proof) is to puddle (with flux) both metals side by side in a crucible and then bring them together. You can also try puddling the silver and dripping molten brass into it a little at a time. For this method the brass should be in wire or strip form held with tweezers or tongs.

Of course, there are variations to these methods and other ways to go about it. This should be enough to get you started though. A little experimentation is to be expected to find out which way works best for you.

If you do it right you shouldn’t need to stir it or agitate it. If you do run into problems with the first method and the alloy doesn't come out homogenous, you can always re-melt it at a higher temperature.

Be sure to do it in a well ventilated area.
 
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