Joining Aluminum without a TIG

I'm kinda thinking of making a model airplane muffler or two. These days the things are generally cast in one piece -- but that isn't going to work for a one-off.

These things have a header that comes off of the engine, then goes into a tube-shaped expansion chamber. See some examples here:

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I'm thinking that I can fabricate one of these with a machined header, machined ends, and a section of tube. But it'll all be aluminum, so how to join the pieces?

I'm assuming that JB weld won't take the heat and will just fall off. But I'm ready to be corrected.

I don't have a TIG welder, or I'd just select TIGable materials and be happy.

I do have an oxy-acetylene set, and I certainly know how to solder.

So -- will aluminum brazing work on this? What sort of selection do I have as far as difficulty vs. results goes? Brands to look for? Avoid? Places to get stuff? I'd like something that's going to be as strong (or nearly so) as the parent material and that can be done on a welding bench with a torch and a vise.

TIA.

Reply to
Tim Wescott
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You can weld aluminum with O/A.

i
Reply to
Ignoramus478

Could you use machine screws to hold the header to the front machined end? And then run a threaded rod through the tube to hold the machined ends.

Or use lost wax casting to make it as one piece.

Dan

Reply to
dcaster

That could be cast with a simple core . For that matter , if it's one that has the inlet port at 90° to the main muffler , cast it as a solid , machine the interior , cap the front with a threaded dome . Built an R/C boat once upon a time . While I was saving up for the radio gear it "got broke" . Long story ...

Reply to
Snag

I've used aluminum solder with success. The hard part is to keep the base aluminum from forming an oxide coating before the solder flows. I don't know what the solder metal is but my file tells me it is harder than aluminum. I bought the rods at ace HW which were similar to these.

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Reply to
Artemus

I have done just a little aluminum brazing. The tricky thing is that it does not flow into gaps (unless there is a technique using flux I do not know about). You scrape the surface with the rod and it will stick where scraped. You can also deposit a blob and then spread it as you scrape with a screwdriver or wire brush. You can tin both sides before assembling and then press together while melting. Be very careful about melting the parts themselves. The braze melting point is only slightly lower than the aluminum.

Reply to
anorton

--FWIW try making a model engine muffler using wood and epoxy; I've seen it done and the accoustics are ...interesting.

Reply to
steamer

Hi, Tim.

JB Weld will easily take 650 degree F. Will change color, though.

Paul

Reply to
co_farmer

I have welded a LOT of aluminum with O/A. Just need to use the same allow for filler as you have for sheet stock. O/A was the preferred method for joining a lot of aluminum items for years. Once you get it down as a skill it's a LOT of fun. Plus with the O/A you can easily remove stresses in the finished product.

Reply to
Steve W.

Avoid the "miracle rods" that don't use any flux. They're primarily zinc and the joints they make are no stronger than JB weld. The stuff doesn't wet and flow like solder, not even close.

Check out

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You can also get flux-filled rods.

I've had very good results with this stuff.

There'a a video demo of aluminum brazing on the home page of this site.

There's also Allstate #31 rod and #31 flux, but I don't know where you'd find it. Grainger used to carry it but I don't see it in their catalog now. An HVAC supplier might have it because that's where it's used -- for brazing aluminum A/C lines.

Practice on some scrap first. This stuff is quite easy to use but it isn't quite as dirt-simple as regular brazing or soldering. Heat control is very important and it takes a bit of practice to get it right. Note his flame control in the video, and the fact that he's using a soft, reducing (excess acetylene) flame. The torch he's using is the Meco Midget. It's an excellent little torch for small work like you contemplate. I have one and love it; it's my "go-to" for most of my O/A work. But any small aircraft torch will suffice nicely.

Get a stainless brush at the welding store to scritch up your metal before trying to braze it or weld it.

Very highly recommended but not absolutely essential: the TM2000 filter lens. Flux used in aluminum torch brazing and welding has a strong sodium flare that blinds you to what's going on at the surface of the metal. The TM2000 filter completely blocks this yellow flare. Regular gas welding goggles are of little or no help. A blue filter, like cobalt glass if you can find it, works after a fashion.

I know it's pricey, but if you contemplate doing much of this it will enable you to get much better results much sooner with much less frustration. I was amazed. Got mine used for half price from a guy right here on RCM quite a few years ago. Very glad I did.

If you want to try aluminum welding with torch, his flux is excellent.

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are other good ones too, but his works great and is easy to find. Use of a good flux is essential for torch welding ally. This is where the TM2000 filter *really* helps. They used cobalt glass back in the day but I don't even think you can find that anymore. OSHA kinda outlawed it.

For filler I just use 4043 and 5356 TIG rod and MIG wire.

He also offers a couple of videos on gas welding ally.

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haven't seen them but I'll bet they're good.

I have no connection with tinman tech other than as a satisfied customer.

Have fun, good luck!

Reply to
Don Foreman

Part of the reason I want to braze is because I have a lot of odds and ends that aren't necessarily going to be easy-to-weld alloys, no matter how nice they are to machine.

But I'll leave your suggestion in the back of my mind -- it's a good one, and if there are such I can just stock up on alloys that are easy to both weld and machine.

Reply to
Tim Wescott

You would have to suggest that. And here I have a Vibration & Stratton engine that's just crying out to be broken into bits and recycled as all sorts of nifty stuff.

Reply to
Tim Wescott

Isn't there a flux you use with O/A on aluminum? Our local hardware store used to stock it years ago IIRC but today they just have brazing and soldering flux.

RogerN

Reply to
RogerN

I've got 5 car/truck rims awaiting cool weather ... when they will join the rest of the wheelium , extrudium , and OldChevyHeadium as ingots . Do you subscribe to any of the hobby casting email lists ?

Reply to
Snag

I assume you've ruled out mousse can mufflers, or the equivalent Bud beer bottle mufflers?

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Pete

Reply to
Pete Keillor

You meant to say "Briggs and ScrapEm" engine, right?

-- Not merely an absence of noise, Real Silence begins when a reasonable being withdraws from the noise in order to find peace and order in his inner sanctuary. -- Peter Minard

Reply to
Larry Jaques

Yes. I have a couple depending on what the material is. Aufhauser Flux10 and Flux14 plus there is some Forney AlumAflux as well. May have some real old powder stuff as well.

Aluminum is an interesting material to weld. Too cold and it doesn't weld, too hot and you get a puddle at your feet!

Reply to
Steve W.

Thin sheet stainless as found in cheap kitchen ware is fairly easy to work with and can be brazed.

jsw

Reply to
Jim Wilkins

No! No no no no no no no!

When I retire, maybe yes. But not now -- I have other things that are higher in the priority list than starting my own backyard foundry.

Reply to
Tim Wescott

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The engine in question is .19 cubic inch, not 1.9.

Reply to
Tim Wescott

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