I have a little die filer I've been meaning to fix up. Its fixed jaw is scarred up, soft, and no longer holds a machine file parallel with the shaft. I had planned to mill a jaw insert from tool steel, harden the insert, and superglue it to the existing fixed jaw (milled away to true it up) but I don't believe superglue will really work and I don't want to go monkeying around with high-tech glues for a tiny job.
I figure the best way to attach a hardened jaw insert is to braze it or silver-solder it. However, the heat of brazing or soldering would certainly play havoc with the heat treating. The little jaw insert will only be about 1/2" by
1" by 1/8" or probably a bit thinner. What if I used air hardening steel, and just let the brazing heat do the heat treating?
One way would be to use HSS. You'd probably need to grind rather than mill the shape. One source of stock might be a 1/8" slitting saw. You can cut this stuff with a dremel, and you can silverbraze HSS without affecting its properties noticably.
"Grant Erwin" wrote: (clip) What if I used air hardening steel, and just let the brazing heat do the heat treating? ^^^^^^^^^^^^^^^^^^ Your air-hardening strip will not cool as fast as it would in air. Remember it will be in intimate contact with the vise jaw, which will also be heated to brazing temperature.
Silver-bearing soft solder, Eutectic 151. Not as good as real silver solder but has about three times the tensile strength of lead-tin. Flows below 800F.
Even soft solder would likely be strong enough in this application. Were I to try this, I'd get a piece of A2, mill it oversize, harden and temper it, then grind it to final size and only then solder it in place. I need to write down the melting temps of brazing rod, 45% silver solder, and plumbers solder, can never remember those.
It probably flows around 500 - 600 degrees. The "coolest" flowing silver-bearing solder I am familiar with is 96% Tin, 4% Silver. It flows at around 430 degrees F. Harris Stay Bright is one commercial version. Radio shack has a silver-bearing solder coiled up in a tiny tube (at an outrageous per-lb price), also of 96 - 4 formulation. Silver-bearing solders are best fluxed with killed hydrochloric acid in paste or liquid form; such as Harris Stay Clean. 96-4 has tensile strength of around 14,000 lbs, which should be enough for a die filer. The low temps of 96 - 4 make it an attractive choice when warping is a concern.
I don't want to get into a pissing contest here, but I can't find where this has a true tensile strength of around 14,000 lbs.
This Matweb link shows it as having 4640 psi (they don't list the tensile for 96Sn/4Ag):
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Other references I have show the various versions (~95Sn/~5Ag) in the same area. Harris's web site has "Tensile Strength (Cu to Cu) 14,000 psi" listed, but I read this as meaning: soldering copper-to-copper. Grant won't be soldering Cu-to-Cu in this application.
Here is an interesting chart I found a while back:
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from this page:
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I don't know, maybe I'm missing something here. That's why I'm curious/asking the question...
Did you really read my whole post? What Harris has on their site doesn't match other sites for the same material composition. Look at how HARRIS STAY BRITE #8 SILVER BEARING SOLDER puts it:
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"Tensile Strength ( Cu to Cu) 14,000 psi Shear Strength ( Cu to Cu) 10,600 psi"
Which is worded differently than your link to HARRIS STAY BRITE SILVER BEARING SOLDER at:
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Other than one has maybe 2% more silver and proportionately less tin they are the same.
I find it odd that neither Matweb nor Indium show anywhere near this kind of tensile strength for the same values.
Indium shows their ID# 121 as 96.5%Sn/3.5% Ag as having a tensile of 5800 psi and shear of 2700 psi. These are similar to those at Matweb. It seems strange to me that the values are so far apart for the same basic compositions (shrug).
The Matweb link showed a product that had other constituents in it rather than just tin and silver. I suppose that had something to do with the difference in tensile strengths.
The other constituents are common at Matweb. If you notice they are in trivial amounts. There will always be impurities involved, it just happens to be listed here.
Take a look at the Indium link:
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Their product number 121.
It is almost identical to the Matweb version and Harris Silver solder. It is much closer to the values that Matweb has. Indium lists other flavors too, not all of them have values for tensile strength though. But the ones that do have with similar compositions are no where near 14,000 psi.
I get the impression that Harris is claiming a tensile strength of 14,000 psi when used for copper-to-copper soldering. If that is so, what would it be for say stainless-to-stainless, or steel-to-steel? At what thickness of filler material? A thick solder job with poor surface-to-surface contact would have a much lower tensile strength maybe?
Maybe Matweb does have a clue:
"32 MPa 4640 psi
Cast solder aged 14 days. Typical Cu joint is 97 MPa."
It appears that they measure the solder itself at 4640 psi and a typical copper joint at 14068.69 psi(converted from
97MPa).
See once again:
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So what would it be for Grant's application, which sure isn't a copper joint...
More food for thought, Matweb shows this for good old
63Sn/37Pb:
"Tensile Strength, Ultimate 52 MPa 7540 psi Cast solder. Typical Cu joint is 200 MPa."
Which would convert to 29,000 psi copper joint typical.
See:
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Interesting stuff, I just wish I would have known about all these different flavors of solder years ago when I could have put them to good use. Ain't no fun getting old...
There can be and usually is a difference between joint strength and bulk properties of the solder itself. A good joint is usually stronger than the solder with which it was made. This is because the process of soldering involves some dissolution of the base metals (like sugar melts in water) to form an intermediate alloy. The matweb cite lists the properties of the solder itself, while Harris is citing the strength of test joints.
Thanks, that makes sense and I kind of suspected as much. So is there anyway you can tell what the strength would be in Grant's application? I suspect that this would vary widely depending on the base materials. Notice too that one of my other posts shows that good old 63Sn/37Pb beats this silver solder in question by a long shot in copper joint tensile strength.
We always used the silver versions at work for better electrical conductivity. I couldn't see/tell where it made any significant difference in joint strength.
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