How to solder aluminium extrusion?

[Johann Klammer]

Hello,

I'd like to join two 2x2cm rectangular extrusions 1.5mm mtrl strength, at 90 degrees, overlapping. One long, one short piece. I've so far tried the rothenberger welding kit(roxxy) with the rolot 604. this kinda works, if I remove the borax from the sticks before soldering, but the temp is rather high and the thin stuff is prone to pitting.

...It kinda works. I've just wasted another afternoon creating a cold joint. The clamp syphons off heat...

Here, on 'the continent' they don't seem to have anything else for soldering alu. The pastes they have at the hardware stores are all Sn based (no Zn content) I'd like a recommendation for solder before I bother ordering from amazon(the spam). Preferrably something with a low melting point.

Also, clamping is a hassle. If I don't clamp, the pieces may have different temperatures, and I get a lose joint or it'll just fall apart when scratching around. If I screw-clamp the clamps syphon away heat and the thermal expansion will deform the extrusion. putting some asbestos cord inbetween kinda works for thermal isolation but is kinda lose and then things might move around. Why are all the spring clamps made of plastic? Are there any good ones?

[Cursitor Doom]

Can you hire a MIG welder where you are? If so, given a reel of aluminium welding wire and a canister of pure Argon, you can make a much better job of it. Welding aluminium with gas is a highly skilled job, but not so with MIG. Any old tosser can do it.

--

"Andrey Semyonovitch really was rather stupid; he attached himself to the progressive cause and 'our younger generation' from enthusiasm. He was one of the numerous and varied legion of dullards, of half-animate abortions, conceited, half-educated coxcombs who attach themselves to the idea most in fashion, only to vulgarise it and who caricature every cause they serve, however sincerely."

- Fyodor Dostoevsky

[tony sayer]

In article [e-mail], Cursitor Doom [e-mail] scribeth thus

We've got an excellent bunch around our way, welders?, more like pure metal fusion the joints they do on Ally look like the bloody original metal!!!

[Cursitor Doom]

Aluminium welding by gas is a very highly skilled craft indeed. The slightest bit too hot and the metal just drops away and you can't see how hot it's getting like you can with mild steel for example. Those guys don't come cheap. I guess they just don't use gas for ally any more with tig and mig so much easier.