I broke the swing-arm of a cut-off saw, need to know how to weld it back. I have a stick welder and can weld steel, but have never messed with cast aluminum.
I also stick weld and have never done aluminum,but several years ago I bought aluminum welding rod from I think it was Northern Tool.It is a zinc based 1/8 bare rod you use with a propane torch.It worked for me and probably will for you.TIG would be overkill for that part.
Tig weld is your best answer. Look for a local welding shop in your area. They usually have a minium hourly fee. I'd guess it'd be between $50-$75.
Let me guess. is your saw made by Chicago Electric by chance? I work as a welder and I tried to fix one of those retarded things a customer brought in, about a year back. The real problem here is a faulty design. Plain and simple. The metal used to make the part is extremely cheap. If you had it welded it would probably cost a bit on labor, and furthermore it's very likely to just break again in the future. See if you can find a used saw made by a name brand, like Milwakee, Delta, or Makita. If it's a tool you use often, then you'll save money in the long run, trust me.
If it has a silvery-grey appearance and is very light, than it is probably aluminum, especially if you did a spark test and nothing happened(ruling out magnesium, which is unlikely for a random part anyway). Aluminum is alot lighter than steel, if you are holding it you would beable to tell. Magnesium is lighter than aluminum, but will give of red spark when touched with a grinder or shavings are lit. Cast aluminum can be welded with a wire spool gun, any certified aluminum shop(and most welding shops in general) would have one. It can also be Tig welded which would take longer but may yield a better result. *** Do not preheat the aluminum that hot, never preheat it more than 150°F, at 300°F you will start to degrade the aluminum, especially if it is an alloy. Aluminum melts at 1220°F but with preheat it would be possible to exceed that(especially with a spool gun). Do not do multipass beads without allowing it to cool. You will need to clean the oxide off the surface with a stainless steel brush or acid, normal steel will leave impurities that will affect you welding.
Yes it could be welded with stick but the rod is hard to find (not that good of quality of weld too). Your best bet is to have it tig welded. If you have never welded aluminum then it is probably best to get someone to weld it for you. I would take it apart and take the parts to a weld shop and get an estimate on it. It may be cheaper to try to get the replacement parts from the manufacturer. Or look on eBay for a saw that's the same and try to find one that is damaged you'll get it cheaper. (30 + years welding - certified)
