Background: a brittle white metal casting (probably some relative of Zamac) broke and the break's not clean. There are visible gaps on the order of several mils (definitely nothing as large as a 1/64") in places. Since I can't weld or solder this stuff, I'm stuck gluing it. The things I have on hand are various hardening time epoxy glues, several viscosity (thicknesses) of cyanoacrylates, and such mundane stuff as Pliobond, Shoe-Goo, and several woodworking glues.
There ARE some "welding" rods for aluminum that are mostly zinc alloy, they're supposed to work on zinc alloy castings as well. Uses a propane torch and no fancy stuff. Not sure about ultimate strength of the joint.
I've not used that stuff for that putpose, JB Weld has been my epoxy of choice for fixing die-castings, sometimes with some steel wire reinforcements across the break. I drill holes, then lace the parts together after buttering up the break faces. Doesn't look too great, but for tool handles and the like, who cares? Holds up at least as well as the original casting. Devcon makes some decent filled epoxies, too, but JB Weld is available at just about every auto parts and hardware store.
Id say Raycrete, which is a multi-mender. Works great for us. Though epoxy works really well on clean surfaces, this would be a job for raycrete.. either that or penetrating epoxy..
| > > Background: a brittle white metal casting (probably some relative of Zamac) | > > broke and the break's not clean. There are visible gaps on the order of | > > several mils (definitely nothing as large as a 1/64") in places. Since I | > > can't weld or solder this stuff, I'm stuck gluing it. The things I have on | > > hand are various hardening time epoxy glues, several viscosity (thicknesses) | > > of cyanoacrylates, and such mundane stuff as Pliobond, Shoe-Goo, and several | > > woodworking glues. | > >
| > > What's going to give me the strongest bond? | > >
| > > TIA | > > Norm | > >
| >
| > Alumaloy will solder pot metal. - GWE | | Id say Raycrete, which is a multi-mender. Works great for us. Though | epoxy works really well on clean surfaces, this would be a job for | raycrete.. either that or penetrating epoxy..
| > What's going to give me the strongest bond? | >
| > TIA | > Norm | >
| | Alumaloy will solder pot metal. - GWE
This was part of the trucks for an O-Scale passenger car and that the area of the break was on the order of 1/8" x 1/16" -- hardly something take a propane torch to, even the so-called micro torches.
Thanks for the product info -- I'm sure it will come in handy in other circumstances.
I fixed a badly broken model airplane engine with JB weld and it held together and has run just fine.. It's just glue with iron filings but it does work if you prepare the surfaces carefully.
| > BTW, I should have mentioned that this was part of the trucks for an O-Scale | > passenger car and that the area of the break was on the order of 1/8" x | > 1/16" -- hardly something I'd want to take a propane torch to, even the | > so-called micro torches. | >
| > Thanks | > Norm | >
| | Sounds like a job for T-88, Norm...
It certainly sounds promising. I'll see if there's any available locally.
There are probably at least a hundred different epoxy glues and variants out there [and that may be a low estimate]. The serious question is how to select one from another -- and how to decide whether to use epoxy or CA or anything else for that matter.
I just did a quick Google search and couldn't find any website that had a comparison chart of the properties of different epoxy products. Does anyone know of one that's out there?
Alumaloy *is* pot metal. It works great for potmetal repair, whether it's welding, brazing, soldering or whatever it might be. The trick is to keep the stuff captive while it's in molten state. "Managing the puddle" is about impossible because it is so fluid, so it must be constrained with dams made of clay, ceramic jigging putty, casting sand or ???
"Managing the puddle" is about impossible because it is so fluid, so it must be constrained with dams made of clay, ceramic jigging putty, casting sand or ??? The trick is to keep the stuff captive while it's in molten state. "
Notice here that by reference to "dams made of clay, etc", Don has offered a gem of trivia to the loyal readers of RCM. Only someone with Don's vast storehouse of knowledge re. "welding, soldering, sticking stuff together" would know the oft-used expression "tinker's dam" refers to a soldering dam.
A minor point here. In this newsgroup (and in machining in general) "mils" are not commonly used. Yes, in dimensional specs for integrated circuits, they are common (as a synonym for 0.001"), but here it has produced confusion with mm at times in the past, so it is best avoided here.
Under what conditions?
Cyanoacrylates tend to be pretty strong -- until they are exposed to moisture. And they do not usually fill gaps well.
Epoxies may be better there, but the bond to the broken edges may not be that great without some form of surface treatment. But, it may be the best for filling the gaps.
Pliobond works best with fairly flat surfaces, and certainly does not fill gaps well.
I've never dealt with (or seen) Shoe-Goo, so I don't know what to expect from it.
Woodworking glues tend to do better at bonding to wood.
My *guess* is that one of the epoxies may be the best bet for you -- depending on the needed strength.
If you need reasonable strength from it, I suspect that none of the glues or epoxies would suffice over time.
An alternative might be to make something from a good grade of aluminum to replace the broken part.
Or -- you could glue the original part together (if it is not warped as suggested by the gaps), and use that as a master for forming a mold into which fresh Zamac could be poured.
Speaking of repairing. I bought a nifty bakealite (sp) clock and I have the tiny bits. What is the best glue for this material? Sorry to jump in midstream but I have never dealt with this before
If it is truly bakelite or catalin, it will resist any sort of solvent welding.
I have occasion to repair a fair amount of bakelite jewelery. If the bits are broken off cleanly, can nestle easily into their original position, and do not see a large amount of stress, super glue does a really good job.
I have glued bangles that had been broken in two with it and in the last fifteen years none of them have come back.
If the joint does not have enough surface area for a good super glue bond, Super glue it into place and back it up with an epoxy scab.
If the bits are just applied decoration that has fallen off, Duco cement is the closest thing to what they used originally. It is not good for patching breaks though.
Thanks Paul The break is on the back and I almost missed it. I'm pretty good at this once I find my glasses. And why is it that you need glasses to find your other ones? Going blind is not that fun.
I would think that a resorcinol/phenol/formaldehyde woodworking glue may be the best for Bakelite, purely on the grounds that Bakelite is a phenol-formaldehyde resin with sawdust, or similar, filler.
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