Hi guys. I have been fabricating an alloy airbox and got to the point where it needs to be welded together. I have seen that alloy brazing rods are available but am wondering if anyone has used them, good or bad ? any suggestions ? or shall i have it TIG'ed ?

Looking forward to hearing from you

Stormy

I would use Tig if you can get it I have used lummiweld but every thing must be spotless Repaired a Bultaco clutch case with it ok But could not get it to work on the cub (oil in the alloy castings)

I Second on the TIG welding of the airbox, Built one for my Fantic 240 that way.I've been told you cannot TIG oily aluminum also,best to find a oxy/acet old tyme magician for that kind of repair.

Edited August 28, 201411 yr by htrdoug

Tig is by far the best way for your airbox,esp if you have made it from clean,new sheet. Its a time consuming and expensive process,so dont expect it to be done nicely for a fiver - unless someone owes you a huge favour.I cringe every time I have to swop out my Argon bottle....

Old oily castings can be welded very well,but take more preparation and sometimes welds dont look quite so good,but are strong enough for use - esp if they are rare parts.

I agree that TIG is the best for welding aluminum. But don't rule out the zinc/aluminum brazing rod. I have used it on many alloy items. As naichuff states above, everything must be very clean - same comment for good TIG welding also.

When cleaning aluminum avoid using steel based abrasives, files or wire wheels. Aluminum oxide is OK but brass is better.

I would not use the brazing rod on stressed parts like swing arms, or handlebars. Because the airbox is not a stressed part, I think the brazing rod will be fine. Be sure to practice on some scrap pieces first. And wear gloves on the hand holding the rod. You might be surprised how quickly heat travel up the rod to your hand.

A good friend of mine fabricates components for race cars and is a TIG and TIG design expert.

He uses special belts (Al oxide from memory) on a linisher to prep surface and remove ally's surface oxide layer. Then uses a wax remover you use for the car painting industry as a wash just before welding up. He uses new paper towels to apply wax remover not rags et cetera.

Some pics of his work! He is a high end fabricator and charges accordingly.

I have a beautiful Kempe Digital TIG and am trying to learn the skill... he has always said to me "First rule in ally welding, cleanliness, cleanliness, cleanliness of surface to be welded.

Mags

TIG is best for your airbox

Abrasives of any kind are not recommended for preparing aluminium for welding as they leave embedded particles of abrasive and binder which contaminate the weld.

Use a stainless steel wire brush, stainless steel wire wool and a special type of file like a rasp.

As previously advised aluminium needs to be cleaned with alcohol, acetone of dewaxing solvent using a brush or lint free cloth.

Aluminium is covered with a layer of refractory oxide that has to be removed in order for the joint to fuse. When oxy acetylene welding or brazing aluminium a very corrosive flux is used to remove this oxide. If any trace of this flux is left on or in the weld severe corrosion and porosity will occur quite rapidly.

I use a KempoTIG 250 but the newer variable frequency sets are better for thin aluminium

Edited September 2, 201411 yr by dadof2

Rivits would have been a good way to go but I assume you are beyond that point. Solid SO rivits and sealant make for nice neat work on AL without warpage. If it's going to be welded fit is king on the joints along with being sure you selected a weldable alloy like most 5 and 6k series.

Edited August 29, 201411 yr by flint45