Volo.

Jan 28, 2012
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By far the biggest thing in welding aluminium is cleanliness. Even if the material is new you must clean it.
The system I use is this:
Wipe the aera with thinners.
Go over the edges with a stainless steel rotory wire brush in a drill. Do this till the area is a matt finish. Any shiny areas will be contamination.
Wipe the weld filler rod with thinners.
Uses new, clean gloves.

Other than that it's just practice.
Thanks, I had been told about the importance of removing the oxidation, I was wondering if the rods were exempt and I hadn't even thought about replacing my dirty old tig gloves.
 
Jan 28, 2012
257
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So the last couple days have been full of set backs and frustrations. When I chose aluminum for this build I knew learning a new skill like welding aluminum would be a challenge but I think I may have grossly underestimated just how hard it would be. I had a few glimmers of success with plates but when I tried to weld on actual bike frame I couldn't even get the two parts to connect. And my steam bending has not been going too well either. The thing about bending wood is you can't just grab any piece it needs to be really straight grain with no run out and its not the kind of thing you can just go out and buy, it requires a bit of digging and luck. I really wanted that polished metal look with the wood and I didn't want to use steel. I'm considering SS but that's another can of worms I didn't want to open.
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Nov 2, 2016
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That's contamination being pulled into the weld from the inside of the tube. Contamination shows up as specks of black. You need to clean inside the tube to have any hope.
Check your gas flow too. Should be pure argon around 7 litres per min
 
Jan 28, 2012
257
1,135
That's contamination being pulled into the weld from the inside of the tube. Contamination shows up as specks of black. You need to clean inside the tube to have any hope.
Check your gas flow too. Should be pure argon around 7 litres per min
Thanks again. I didn't know the underside would matter. I think the inside of the frame has a protective coating on it. On a side note; Do you think trying to weld 6061 to 7005 would be ill advisable? The head tube I was planning to use is off a bike that's labeled as 7005 and I "think" my plates are 6061 though I grabbed them from a scrap pile at work and no one was really sure.
 
Nov 2, 2016
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Thanks again. I didn't know the underside would matter. I think the inside of the frame has a protective coating on it. On a side note; Do you think trying to weld 6061 to 7005 would be ill advisable? The head tube I was planning to use is off a bike that's labeled as 7005 and I "think" my plates are 6061 though I grabbed them from a scrap pile at work and no one was really sure.
I've not had experience with 7005. What rods are you using?

Be aware that some aluminium alloys need heat treatment after welding to recover the strength lost when the weld heat anneals the metal. I think you should check this before going any further.
I'd have gone stainless.... 304 preferably.
 
Jan 28, 2012
257
1,135
I've not had experience with 7005. What rods are you using?

Be aware that some aluminium alloys need heat treatment after welding to recover the strength lost when the weld heat anneals the metal. I think you should check this before going any further.
I'd have gone stainless.... 304 preferably.
4043 rods. Yes I was aware of that bike frames were heat treated but when I asked a few welders I knew if they ever did that they looked at me like I was crazy. There is only a mimimal amount of welded aluminum parts in this design. I think at this point my plan will be to secure them in a removable fashion so I can replace them later.
 

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