appropriate adhesive?

I'm finally getting back around to fixing up my little die filer. Its chuck is pretty munged after years of having files jammed into it, and
it doesn't work right anymore (i.e. doesn't hold the file parallel with the shaft). I figure I'll mill away the "fixed jaw" and make a hardened shim and glue it on. There will be little stress on the glue joint as it will be held in compression, but there will be some. I'll be gluing a ground surface to a milled one. Would cyanoacrylate (superglue) be the right stuff to use?
Grant
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On Mon, 20 Dec 2004 15:09:24 -0800, Grant Erwin wrote:

Seems to me that silver soldering and quenching the shim would work better. Either that of build up the worn jaw with a hardfacing rod and grind down to finish shape.
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Jim Levie wrote:

Nope, don't want to monkey with the original paint. - GWE
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I suggest JB Weld, if you can stand the long cure time.
Bob Swinney

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<unlurk>
look at this www.coolchem.com
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it
If you want compression strength, a good grade of epoxy (not hardware-store stuff) will give you around 4,000 psi or, if it's 100% solids, a little more. Cyanoacrylate is a fraction of that, and its adhesion isn't nearly as good as properly applied epoxy. One-part polyurethane (Gorilla Glue) is somewhere in between.
I don't think you need a lot of compression strength for that job. Personally, I'd soft-solder it and screw the paint (around 5,000 - 7,000 psi compression, and good adhesion). But my second choice would be an aluminum-filled epoxy. I think that's what JB Weld is, but I've never used the stuff. The tensile strength of al-filled epoxy is questionable but its adhesion strength is good, if you know how to apply adhesive to metals (a long story, for another day). But its compression strength may be somewhat higher than unfilled epoxy. Anyway, industrial-grade aluminum-filled epoxies can run up to 6,000 psi or so compression.
My choice for ease and (probably) perfectly acceptable performance would be polyurethane. It covers a lot of sins, partly because it's flexible and partly because it has excellent adhesive strength.
-- Ed Huntress
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Ed Huntress wrote:

Another good choice, but only a LITTLE DAB in the center if you don't want it to foam out. Make sure it's clamped!
The important part is thorough degreasing with acetone, lacquer thinner or even nail polish remover.
Ken Grunke
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I worked on a project once which used a mind-boggling epoxy from Armstrong to hold things together where we could not use bolts (electrical conductivity would have been bad). It was a two part epoxy which could be made more or less flexible by varying the ratio of parts A and B, and required a long time (days) to cure at room temperature, or a much shorter time at elevated temperatures. A12 sounds like it might be the stuff:
http://www.ellsworth.com/Catalog/Armstrong.pdf
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wrote:

hardware-store
as
Maybe. Industrial epoxies are a complicated story. Most RTC (room-temperature-cure) systems use a polyamine hardener, and A12 sounds like it might be one of those. They often benefit from a cure at slightly elevated temperatures, but they're usually cured at *one* temperature for a given amount of time. Polyamine hardeners are versatile and can give good performance. They're a common type of hardener in hardware-store epoxies, and, typically, they're mixed at a 1:1 ratio with the epoxy itself, at least in consumer versions.
When you hear someone say "A/B," however -- especially when they're talking about high-performance, industrial-grade epoxies, they're often talking about "A/B cures," rather than about mixing parts "A" and "B." An A/B cure is a two-stage cure, used with different hardeners, and it produces higher strength, toughness, and heat tolerance than typical RTC epoxy systems. A/B cure epoxies are used for laminating commercial and military aircraft parts, Formula 1 race-car parts, and so on. They're also used for bonding metals in industrial applications.
A typical A/B cure would be, say, 6 hours at 200 deg. F and 10 hours at 250 deg. F. That's not representative, just one possible example.
Don't try it with Elmer's Two-Part Epoxy Adhesive. <g>
Ed Huntress
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Grant Erwin wrote:

CA is very brittle so it likely won't last a long time unless you just don't change your files. Epoxy is much better, more flexible. JB Weld would probably last forever, at least if you degrease the joint first.
Ken Grunke
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