Brazing aluminum

Greetings all -
How do you braze or solder a brass fitting to an aluminum manifold? Thanks, Willer

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A tin-zinc solder or pure tin would probably work with the right flux, some better than others of course. Tin silver solder (as Harris Staybrite) might work with the right flux. Harris Staykleen is not the right flux here, don't know what might be.
Some will say that lead-tin solder works if the al is scrubbed while soldering. I've never had what I considered satisfactory results from this, YMMV.
I would try Aero Solder and flux from http://www.tinmantech.com/html/aluminum_gas_welding__brazing_.html#solder
It works very well for al-to-al and/or al-to-copper, so I'd expect it to join al to brass as well but I've never tried it. If you're not in a hurry, I'll try it with brass when I return later next week and let you know how it works.
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KISS. ;-) You put down the torch, and drill and tap the aluminum manifold to NPT threads. (Or metric if you're on the other side of the pond.) Then you thread the brass fitting, coat with the appropriate thread sealant for the material in the manifold (Teflon tape or good ol' Rectorseal #5) and screw them together.
Joining dissimilar metals like that can be done - J.W. Harris says to make it a two-step joint, with a piece of steel tubing or pipe in the middle. First braze the steel to aluminum with 'AlBraze-1070' filler and flux, then the copper/brass to the steel using one of the 'Safety-Silv' series fillers and 'Stay-Silv' flux.
First go to http://www.jwharris.com/ to get in their Frames setup, then look at the chart at http://www.jwharris.com/jwref/chart /
I would be concerned about the differing rates of expansion making it crack in service. And if the filler metals get mixed when you put it together, all sorts of odd things can happen...
--<< Bruce >>--
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Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
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You can't, because the thermal coefficients of expansition for these two materials are so totally diffent.
Harry C.
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See http://www.tinmantech.com/html/aluminum_joining_to_steel.html
Hold my beer....

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You think that's scary? How about MIG welding aluminum to steel?
http://www.thefabricator.com/Articles/Fabricating_Article.cfm?IDg6
Tim
-- "California is the breakfast state: fruits, nuts and flakes." Website: http://webpages.charter.net/dawill/tmoranwms
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I'll try brazing first.
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Not to mention the electrolytic corrosion that will immediately start at the jumction. Bugs
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