Originally Posted by
Truckracer
I tried some of those low temp aluminum brazing / soldering materials without success. Had trouble fixturing the muffler during assembly as aluminum conducts heat so well it was easy to disassemble previous welds doing the next weld. Once assembled, welds quickly failed. When I work with aluminum these days, I just have it TIG welded by a pro and the cost is still less than a commercial product. Maybe you will have better luck than I did.
Steel is much easier to work with and is easily welded with an oxy / acetyl torch using steel filler rod. When I can find it, I'll post a photo of one muffler I made for a scale Zero.
Here are the photos I promised awhile back. This muffler, made in 2007 and still in service today is all steel construction and was assembled from cut steel flat stock. The area where it bolts to the engine is 1/8" thick and the balance of the muffler is relatively thin stock though I no longer remember the thickness. The exhaust pipe is a cut off table leg. Note there is a support strap to bolt to a motor mount bolt. The notch is there to clear another mounting bolt .... I think. The whole thing was oxy / acetylene stick welded and the black was BBQ grill or header paint, again I no longer remember for sure. This is used on a 3mm 53 in a Yellow Aircraft Zero and it really wasn't as heavy as I expected it to be. Not a problem on a short nosed Zero as I still had to add nose weight.
I would go with steel again unless I needed a super light muffler then if I couldn't fabricate one, I would have a company such as Jtec build a custom muffler which I have done several times.
