Question: Best Brass-to-Brass Adhesive?

[the elephant]

I do not want super glues, here. I want adhesives that have both strong resistance to pulling and shear forces. In fact, shear resistance is probably the more important of the two.

I recently watched an interesting video by an automotive guy who did a series of tests on most of the popular glues used in that field to fix metal cracks and such. And oddly enough, despite all the high-tech, modern solutions, good, old JB Weld was the best in the three tests he ran. And you could easily see what failed each time. Most of the products could not bind with the metals no matter how well he followed the instructions for prep. (And he did an excellent job using the things most DIY mechanics would have access to, and that is what counts. Laboratories are not available to me when I work. My laundry room stores all I have, and my workspace is in the open-ended carport. To me, this guy's tests were spot-on for actual use.

So, again, most of them, when they failed, lost the bond with at least one of the two surfaces. The most durable ones all failed with the glue itself breaking in half — but in all of those cases, the glue stayed firmly bonded to the metals on both sides. When the glues bonded well with the metals they were usually about five times stronger: they held more weight, they resisted shear, etc. And JB Weld "Original" did the best. Oddly, the high temp JB Weld and ALL of the quick-dry glues failed very quickly. He tested some very expensive stuff along with the old-school gunk, so I felt this was a useful video to watch.

So he was bonding stainless hardware to mild steel plate. How about brass-to-brass connections? I saw a thread here about building a tuba using only glues since these products have advanced so much recently. The test I watched belied this to a certain point. And it did not test brass (or any other copper-based alloy).

Does anyone here have any hands-on experience gluing a part when it would be better than using high heat and soft (or hard) solder and flux?

I am thinking of doing this to a part that will not see much stress. I have been hunting for its perfect location using a dab of blue Loctite. Once I was finished testing a location, I would snap it loose, clean up the surfaces, and affix it to a slightly different location. (I have it where it needs to be now.) The Loctite worked so well for this that I think I want to epoxy the guide block to the 1st piston casing more or less permanently, and I do NOT want to braze it in place. What should I use to accomplish this? Low temp silver solder comes to mind, but something like JB Weld seems like it could be much easier/faster/neater.

You can see why I am tired of heating the thick casing over and over. This is difficult to soft solder in place outdoors in the wind. So something like JB Weld would make life much easier for me. Tell me why this would be a terrible idea or I am going to do it. Also, tell me about any epoxies or adhesives that would be better than JB Weld for use on copper alloys.

[Rick Denney]

Any industrial epoxy will probably work. I like JB Weld, and have used it a lot. It’s fine for your purpose, and probably as stronger as soft solder. There is stronger stuff out there, though. I used 3M Scotchweld DP430 to repair the broken handle shaft on the cast iron idler cam on the lathe, including running a threaded stud through a lengthwise hole I drilled through the broken shaft, and encasing it in epoxy. I nearly drilled away the width of the bolt to ream a hole for a taper pin to lock the handle that goes on that shaft, so the epoxy is really doing most of the work of keeping the iron nailed to that stud.

Waaaay overkill for your purpose. Iron is much harder to stick together than brass because it flakes off graphite. And this handle gets used constantly and often requires some significant English to coax those square-cut gears for the apron crossfeed into meshing.

What I don’t like about 3M is the price and the requirement to use their expensive applicator gun.

Is it better than JB Weld? Yeah, probably. Better enough to be worth the price? Nope. Better for your application? Not a chance.

McMaster sells both and lists both as being appropriate for brass (along with most other metals, glass, most plastics, false teeth, birds nests, dried dog poop, and most other substances).





Rick “3M has twice the shear strength of JB Weld, making it 20 times stronger than you need, instead of 10 times stronger” Denney

[the elephant]

JB Weld it is, then.

Thanks, Rick!

I feel the need to hang out at the local O'Reilly's…

Wade "only using internyms when Rick is in the discussion" Rackley

[bloke]

I find this information interesting...

...and am appreciative of it.

Actually, I was already planning on using one of those two specific products to (as best as can be undone) undo something very stupid that another repair person (name neither revealed here nor privately...to protect the guilty/stupid) did - prior to my ownership - to one of my instruments.

I feel more enthusiastic/confident about using that product, now.
I would also like to know if (assuming a surface is oil-free and clean when the product is applied) if (ok...the cheaper of those two) the product is completely oil/petroleum-resistant, once it has dried/cured...(I suppose - based on the industry to which it caters - it has to be.)

My use doesn't need to be able to support the Eiffel Tower nor repair a door in the process of being hammered on by King Kong...BUT it needs to STAY.

For different reasons than Wade, I would prefer to not go the "solder-heat-and-flux" route.

[the elephant]

Sometimes all that artsy-fartsy torch work we do is neither needed nor wanted. Like you, I need this part to stay put, even if I dribble lamp oil all over it. It will not suffer bumps or yanks, so shear and pull resistance is not that important. It will not suffer from extremes in temperature, pressure, humidity, etc. as I only use my tubas within the troposphere.

Yep, lamp oil is probably the worst thing it will ever be exposed to.

Mainly, I don't want it to fall off at work, which would be rather inconvenient.

I just need someone to hold my hand and tell me that it's going to be okay.



With all this in mind: how do you get JB Weld-ed parts loose from one another? Heat? Solvent? Prayer? Bribery?

And, if it is heat: how much?

[Rick Denney]

I glued a pin into an aluminum carburetor body to make the “parts-only” Weber 45DCOE race-car carb for which I had paid ten bucks hold its float hinge properly. That part sat in racing gasoline for two years after that. It’s still sitting on the shelf here.

That was JB Weld, installed in 1980. Still solid.

I think it does fine with petroleum solvents, once cured.



Rick “only thing left here from the Killer Corolla, except for some pics and some broken plastic trophies” Denney