Soldering Guards

nickandersonart said:
Curious as to whether more people choose the low-temp solder vs higher temp brazing.
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I suspect there are makers using high temp/ high silver solder in the 46-56% range, but they aren't talking about how they get it done.

Low temp soldering apears to be the most prevalent and easiest. I was working on my first slotted guard recently, refitting a old Schrade 165 and I'm sure I would have ruined the blade using 46% or greater hard solder and a braxing torch. Soft soldering it was difficult enough.

I also once assumed everyone used a high temp high silver, hard solder
 
Bill DeShivs said:
There is some bad information here.
I'll attempt to explain.

What you want for guards is silver-bearing solder. It contains around 4% silver. This silver content allows the solder to adhere to both stainless and carbon steels-as well as non-ferrous metals.

A soldering iron will not have enough heat to solder a guard. The cheapest was is to buy a standard propane torch at a hardware store. You can usually get your solder there, too.
The metals in the joint have to be fresh metal-filed or sanded bright. This is very important. The joint also must be clean, but most people make too much of the cleanliness.

Apply your flux to the joint, then heat with a GENTLE flame from the torch. You only want to get the pieces hot enough to melt the solder. Apply solder to the joint, and it will flow into the joint. Remove heat as soon as the solder flows.

After the joint cools, wash it with soapy water and dry.

Do not try your first soldering on a knife. Use scrap pieces to practice. Also- be wary of using things like a vise, which will act as a heat sink and prevent the joint from getting hot enough.
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This is very good advice.
 
Somebody out there has an easy time soldering stainless to 1095, and I wish they'd chime in, because despite a background in everything from silver jewelry fabrication to fancy gates and railings (oh, and then there's all those knives :) ), that's one thing I just don't attempt anymore.
Use JB Weld, like the best makers do, to bed that guard, just make sure the fit is as good as you can make it.
Oh, and pinning rivets through the guard and blade is pretty important. Do that and it'll be hell for stout.
 
i agree the low temp silver bearing solder is better. i do not think it is any stronger, but the normal tin/lead will turn dark gray after a few years, sta-brite was invented for the food service industry, and stays silver. after soldering, i scrub the joints with a toothbrush & baking soda/water paste, then give it a bath in windex. those two things neutralize the flux acids.
 
Tin-lead solder will not work on stainless steel. This is why silver-bearing solder is used, and it also has more strength.
Using my method, soldering stainless to high carbon is easy.
 
In Jim Hrisoulas' book "The Complete Bladesmith" on page 68 he has a section on using non-leaded brass or other brazeable material to attach guards. He says the heat required for using this technique is around 1500F.

I'm guessing that the added advantage is higher structural integrity. Are there people here who are using this method, or have used it before? If so, what would be the best way for keeping the blade edge cool to prevent overheating the blade edge while brazing?

Also- with either of the methods, silver bearing solder or brazing - is it possible to use ochre or whiteout to prevent solder from flowing to undesired areas? Seems like if the fit of the guard against the ricasso is really tight, it could be sort of sealed off from the ricasso side of the blade using whiteout to prevent solder from traveling up past the guard.
 
i guess if you hung the knife by its lanyard hole with the blade in water and soldered the guard it could work. but i would be concerned the water would be enough of a heat sink to make it difficult to bring it up to temp. the solder usually will not stick where there is no flux. i solder from the bottom, so there is no chance of making a mess to clean up on the top. the solder gets sucked in, i have never had a problem with a joint being too tight to allow the solder to flow although i have read a .003" space is optimal for solder to flow. as far as structural integrity , if you ever try to remove a guard that has been soldered with no pins through it and plain old 60/40 tin lead with a hammer or whatever, you will ruin the knife and guard in the process. for me that is enough integrity. in the book you mentioned, in the last paragraph he recommends not brazing guards :)
 
I did see that as well, just curious if it's better for certain applications but if the silver bearing solder is that strong, sounds like it should more than do the trick :)
 
Bill DeShivs is passing out good advice. I've soldered a few thousand guards on in the last 10 years and use the same method as he described. I've used different series of stainless, brass and bronze on W2, W1, O-1, 1095, Cru forge V, 5160, 1084 and D2. If you take the flame away when the Stay Brite melts its around 400 degrees and that's not a problem at the guard area.
 
i was curious why he went into such detail about it, only to suggest not doing it at the end lol. i understand your concern, solder is so easy to bend with your fingers, it makes sense to wonder how strong it really is. but if you took a 1/8" piece and tried to bend it, you would notice suddenly it seems stronger. the smaller something is, the more lever force it takes to bend/deform it. with a solder joint 3 human hairs thick, it takes a lot of force to deform it.
 
nickandersonart said:
I'm guessing that the added advantage is higher structural integrity. Are there people here who are using this method, or have used it before? If so, what would be the best way for keeping the blade edge cool to prevent overheating the blade edge while brazing?
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Aside from the appearance differences, it does offer a higher "shear" strength for the dissimilar metal bond. Though it seems one would need to do the brazing somewhere near the "hardening process" of making the blade for a hard solder.

A quick check of the Harris products website showed 10,000 psi for 6% filler metal, and another shows more than double that, 25,381 psi for 56%. and about 1000°F difference between the two welding temps.
 
This thread is missing photos.. (posted but realized OP was asking about soldering disimilar metals - sorry)

Here's how I positioned a recent knife for soldering brass to 1095/Ni damascus. Albeit it was the first soldered guard that I've done. This was done post heat treat of course.

During and after pinning the guard on, make sure the area to be soldered is very clean and that you use flux. I lightly sanded, wiped with acetone and waited to make sure there was no acetone residue left.

The point is to heat the tang area just above the bolster to bring the tang and bolster up to the temps suitable for the solder to work. This while protecting the blade from heating up too much.. Water is good for this as it boils around 212F which should be safe. It'll take a fair amount of heat to warm the water near boiling so you have a while to heat up the tang. Bubbling/boiling is a good indicator of where you stand temp wise. The phase change during actual boiling will also pull a lot of heat energy from the submerged blade if it comes to that.

The flux and solder should melt and through capillary action be drawn into the gaps to be soldered. To me it makes sense to solder the back of the bolster and the solder will be drawn down. Just look for the solder line on the front of the guard to develop without the solder dripping down too much. This should minimize cleaning time on the front and keep the majority of the clean up work closer to the handle.


Sorry for the rather large photos.


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you should solder from the bottom up so you achieve 100% penetration , solder follows heat , your solder job there was probably surface coat only . You should avoid heat sinks like your water bucket , with the right solder you will not hurt the heat treat .
 
Thanks Jack. You're right about the solder following the heat. Also that having too effective of a heat sink can pull too much heat and can result in a poor bond.

As long as the guard and area near the ricasso are clean and past the critical solder temp, there should still be a good bond. The soldering job can be tested at the seam of the front guard. The temper color on the ricasso should also be evident when it gets up to temp.

Sorry, I don't have not photos showing the solder characteristics on the front of the guard.


Cheers,

-Andre
 
All I can add is reinforce an earlier point, which is do NOT do your first try on a knife.

I tried soldering a guard onto my second knife (blade pointed down, fluxed, heated the tang/guard with a torch just enough to get the solder to melt, then applied solder), I was using regular leaded solder, 60/40 I think. It melted right down past the guard and all over the blade. Huge mess getting that apart, getting the solder off everything, started over on the guard and blade finish... I clearly messed up in almost every possible way! So yeah, practice on something else first. I'm gonna stick with epoxy for now!
 
A little tip I can give about soldering is how to control where it goes. When I do it I put a pencil line where I don't want the solder to go. The solder will not cross the line and it acts like a dam. That being said you can use this to do all kinds of things. If you want to solder from the top then use the pencil and make the point blunt and draw around the seam where you want solder. This will put pencil line on both sides of the seam that needs soldering. I then make the pencil line wider and your good to go.
 
Natlek said:
Is there any reason why not weld guard with a bronze before HT ?
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Probably not if the (heat treatment) temperatures stay below the melting point of the metals. And I am guessing you mean 'braze' as welding steel to brass or bronze is probably next to impossible (I've never heard of it).
 
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