Welding Aluminum Gary Fisher build I am planning.

[Roadkill]

I have the sweet Tassajara made by Gary Fisher.. (I think it's sweet) .. anyway it is an aluminum bike and the chain derailleur cracked off and I was wondering if I can use this welder I just bought for 100 that looks like new **applause**

Amazon.com: Schumacher - Turbo 145 MIG/Flux Welder - 120 Volt (90441): Automotive

and want to weld the piece that holds the derailleur back on. I have some experience with steel welding but never attempted aluminum before. I can practice on some other parts and seat posts to get a feel before going at the main course. Can this be done? I have dozens if not a hundreds of hours behind a sloppy stick (please refrain) and flux wire feed welders.

Anyway that said.. I will someday make a near aluminum frame frankenbike now that I have this welder.

[Junster]

I can't see the back of that welder and I didn't see for sure in the description. To weld aluminum you have to have argon sheilding gas. Second problem is you usually need a spool gun too. Aluminum wire is soft and many times it will not feed all the way down the normal gun lead like steel will, and if it does it usually won't feed smoothly. A spool gun carry's the aluminum spool at the gun so it doesn't have to feed thru the lead. They also make now what are called push/pull guns. The gun has a set of powered rollers that pull the wire along with the set that pushes the wire in the welder. Both those options are expensive add-on's and you need to make sure the welder has hookups to use them. It does say you can reverse the polarity. You only need to do that to change from flux core wire to solid wire with gas sheilding so I'm guessing it does have hookup's for a gas bottle. Your aluminum frame bike is also heat treated. Once you weld on it that's gone in the area you weld and it will be soft. Don't know how'd you'd re-treat it.

[Roadkill]

Originally Posted by Junster

I can't see the back of that welder and I didn't see for sure in the description. To weld aluminum you have to have argon sheilding gas. Second problem is you usually need a spool gun too. Aluminum wire is soft and many times it will not feed all the way down the normal gun lead like steel will, and if it does it usually won't feed smoothly. A spool gun carry's the aluminum spool at the gun so it doesn't have to feed thru the lead. They also make now what are called push/pull guns. The gun has a set of powered rollers that pull the wire along with the set that pushes the wire in the welder. Both those options are expensive add-on's and you need to make sure the welder has hookups to use them. It does say you can reverse the polarity. You only need to do that to change from flux core wire to solid wire with gas sheilding so I'm guessing it does have hookup's for a gas bottle. Your aluminum frame bike is also heat treated. Once you weld on it that's gone in the area you weld and it will be soft. Don't know how'd you'd re-treat it.

Yes it has the gas hook up. It does not have electric rollers in the gun I fear.That is something about the softening of the aluminum. Thank you for teaching me that. I will google treating aluminum later and will probably end up attepting the job and failing. Might as well try. I will look for argon and then attempt. The wilder came with a nipple for gas input on the back and no hose. I will look for that later as well. Hmmm I imagine stainless is a challenge as well.

Thanks again for the knowledge. I have a few welding books and will look in them for aluminum information.

[ratty]

I think the best way to weld aluminum is with a TIG, but even still it is very tricky. I would pay somebody to do it. I'm pretty sure that either way you weld alum, mig or tig, you must reverse the polarity. I was reading a post the other day on one of these forums about 'brazing' aluminum with a mapp or propane torch and some aluminum rods from lowes....here it is, check this out....looks very interesting
http://motorbicycling.com/f3/brazing-aluminum-9796.html

[Roadkill]

Originally Posted by ratty

I think the best way to weld aluminum is with a TIG, but even still it is very tricky. I would pay somebody to do it. I'm pretty sure that either way you weld alum, mig or tig, you must reverse the polarity. I was reading a post the other day on one of these forums about 'brazing' aluminum with a mapp or propane torch and some aluminum rods from lowes....here it is, check this out....looks very interesting
http://motorbicycling.com/f3/brazing-aluminum-9796.html

Thank you.. I just tried the welder and oiled the feed drives a bit and it is running better than the Harbor Freight USED TO.. Already got it all ugly. I am still going to have fun with it.. Welds better and DID NOT pop a fuse YET. Thanks again.. I fear your option may be the best one.. I might even be able to "beef it up" around the crack and (please refrain) make it stronger than original.