Gas Welding aluminum

| Sounds about what I would have said. I found there is a subtle change in | the surface of the aluminium before it drops on the floor, I learned to
| recognise this and all went fine. I have never used anything other than | standard OA welding googles for Al and never had an issue with being | able to see what I was doing clearly. People mention using special | lenses to cut the flare from the glowing flux but I have never | experienced this. I have never welded Al with OA extensively and these | days would typically use TIG unless I had a benefit from using OA, | typically it leaves a more ductile weld which may be beneficial if you | are doing panel work.
I'm interested in how you do this, since most information on your method is highly lacking on the web. Please, tell me more!
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Have you read all the responses to Brent Philion's original post. There has been alot of good information given. My initial response was mainly to agree with the reply by Buy_Sell but ad that against what most have said about the need for special goggles I have never found this a requirement.
carl mciver wrote:

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David Billington wrote:

You might want to try out the special lenses. They make a night and day difference if you are Al welding (I couldn't imagine doing .025-.035 well without them). I don't find it as necessary brazing Al.
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On Sun, 22 Jan 2006 02:08:53 -0500, Brent Philion

O/A can definitely be used to weld aluminum. It is the first choice of many for sheetmetal on aircraft and various automotive work. I do it routinely with 1/16" and less, prefer TIG for thicker materials. It would take a big tip and a lot of gas to weld 1/4" aluminum, but it certainly can be done. 1/16" to 1/8" is easily done with O/A. Some say that gas welds in thinner metal are more ductile than TIG or MIG and hold up better to subsequent metalworking operations like planishing or further forming.
I don't think welding aluminum is any harder with gas than it is with TIG. With metal 1/16" and less I think it's easier -- but read on.
You can order a videotape on O/A welding of aluminum from www.tinmantech.com I've not seen it but it's probably a good start. You can also download a short video showing aluminum being gas-welded from www.cut-like-plasma.com It's objective is to sell the Henrob torch. Don't worry about that. Your torch will work fine. The Henrob's performance as a cutting torch is impressive, but others have indicated preference for other torches for welding and the Henrob is a rather pricey torch. Your torch, with appropriately-sized tips, should work fine.
Special requirements: yes! Aluminum welding requires flux. The reverse polarity part of the AC cycle cleans oxides with TIG, flux does it with gas. Some welding stores will have it. The tin man and cut-like-plasma offer it too.
Aluminum flux produces a bright incandescant "flare" that must be blocked in order to see the puddle and to see when a puddle is imminent. Eyewear that blocks that flare is absolutely essential to successful gas welding of aluminum. Regular goggles don't do it, not even close. It's not a matter of "dark" but one of blocking the flare without obscuring the puddle.
Cobalt blue glass was used for many years, but is no longer used because it doesn't block some harmful rays. There's probably some OSHA overkill there for the occasional user, but I've used them and can tell you that there is now a far better choice available.
The TM2000 green dydimium lens, available from the tin man, cut-like-plasma and some other places, is a bit pricey but I'd regard it as the single most important tool to have for gas welding aluminum. It works extremely well. I know of no cheaper alternative that works remotely as well.
Cut-like-plasma does offer an alternative lower cost lens. I've not tried it. HIs video is obviously shot thru the TM2000. If you're serious about learning to weld aluminum with gas, I would strongly encourage you to get a TM2000 filter.
The other indispensible tool is a stainless steel "toothbrush" for scrubbing the metal clean just before welding. They're available at any welding store for well under $2.00 each. If you're familar with TIG welding aluminum you know about those already.
I don't know anything about gas quick-connects. I sure wouldn't use compressed-air quickconnects, don't even think about it! Those either leak or are about to.
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Go to http://www.tinmantech.com
They have all the info, and supplies, for gas welding aluminum.
Allstate also sells aluminum brazing supplies. They call it Allstate #31
<http://products.esabna.com/index.html/session_id/acd33ecaa687e391f2479c1 166c1b5a3/screen/filler_metals_product_detail/category_id/id4367f2a976b2f 9.04496423/category_ids/3143>

I use Western brand quick disconnects for all my torches. They work very well. I also use their disconnects for my shielding gasses.
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On Sun, 22 Jan 2006 10:34:22 GMT, Ernie Leimkuhler

Good stuff for thin metal, be sure to get the #31 flux as well. It doe not work well (for me) on metal over .062" for some reason. Allstate #31 was developed for HVAC work, joining aluminum tubing in refrigeration systems. It works really well for that. I first saw it demonstrated at an ASHRAE show when it was first introduced. I was amazed.
Tinmantech also offers a similar brazing material, Aerobraze, with companion flux.
I've had varying reports from others on these two materials: some say one works for them while the other doesn't, and conversely. I don't know why. I like them both on thin metal. The Allstate #31 is way lots cheaper, available from Grainger.
The difference in temperature between either of them and welding is less than 100 degrees F. That's a big difference on thin metal, but I find it as easy or easier to weld as to braze on material .050" and thicker. Neither of these materials work well for butt joints; they're better for fillet or lap joints as one might design for brazing. Butt joints and outside corner joints are best done by welding.
I guess they're really different processes. I can cut a preform out of either Allstate #31 or Aerobraze, set it in place with appropriate flux, heat until it wets and flows resulting in a joint that looks just like a silverbrazed joint in brass or steel. Welding aluminum is, well, more like welding, melt and dab while controlling a puddle.
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Ernie Leimkuhler wrote:

I was wondering when somebody was going to post this URL.
The "sharp flame point" is a carbonizing flame(?) And aluminum welds need the extra carbon.
One tip (I think from Bud Davisson?) was to place a wooden match stick on the weld line and just weld thru it... Haven't tried that one - but ?
The metals need to be absolutely clean. Tinman recommends a stainless steel brush that is not used for anything else - ever.
and all the rest...
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Richard Lamb wrote:

What the purpose of this?
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wrote:

I find it easier, but then I've got a fair bit of OA experience with steel and I'm a complete numpty with TIG.
One thing I did find is that the aluminium alloy affected things. Magnesium alloys (about 15% Mg) in vehicle or aircraft sheetmetal was no problem to work, purer aluminium didn't give me such good results. Welds seemed structurally OK, but never looked as neat.
Tool up with the right fluxes and go to it for some practice. These things are fairly easily available, but the English flux for 15% Mg is obviously the best stuff - if only for the name "Hari-Kiri No. 2" ! (read the Landrover service manual).
A word on fluxes though - these things are horribly toxic when heated, and their vapours. I'd been using them for years, but I blanched when I found out just what was in them afterwards. Now I'm a _lot_ more careful about ventilation than I used to be.
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Brent Philion wrote:

Gas welding AL is pretty tricky, and if you only need to weld AL infrequently it might be better to hire a TIG set.
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Brent Philion wrote:

So from what i Gather from what everyone has said the only differences and things needed to OA weld Aluminum on top of what i currently have are
1. ALuminum welding flux
2. Upgraded Eye protection to protect against Sodium Metal flares.
3. Possibly a better means of cleaning the AL before welding (acetone?)
4. Better ventilation/fume extraction because some of the stuff coming off the weld will be really toxic stuff (or at least stuff best left outside of my lungs) And stuff more Caustic than say a plain old Cigarette
For question 2 will an autodarkening Welding helmet in the OFF position (Shade 5) cut it for getting rid of sodium flare? (I have a Miller Xli helmet already and if it will work i'll be happy)
Otherwise my eyes and ears have served my great for my 26 years so far and i'd like to at least have them in decent shape for 3 times the 26 theyve done. I'll accept slowly starting to fall apart at age 78 but i'd just as soon be nice to my eyes and ears and such before then
Safety equipment to me is not a cost its an investment in the quality of my work and in the preservation of my keester to weld again another day.
As for doing it its not that much harder than TIG and the added difficulty does not seem to be enough to justify my running out and buying an AC tig Capable machine to replace my XMT. the technique IS different but its close enough that I should have minimal adjustment pains compared to say the jump form Stick to TIG
Am i basically on the right path with the Synopsis i've came up with here?
By the way Thanks to everybody for all the info
Brent Philion Ottawa Canada
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On Mon, 23 Jan 2006 20:41:32 -0500, Brent Philion

Not nearly as well. A shade 5 pretty much darkens everything. The idea here is to block the flare without otherwise reducing visibility much.
Sodium flare has a very narrow spectrum or band of colors around yellow-orange, a small percentage of the total visible spectrum. If a filter blocks those colors much more strongly than others, then your visibility of the work and puddle is greatly improved. The TM2000 is about a shade 5, but it completely blocks the sodium flare. Totally, as in gone. Your first clue that you are near welding temp is when the flux melts -- and you can clearly see it melt and turn clear. The TM2000 can also be (and is) used for gas welding steel including 4130, and cast iron.
I don't sell these things or get a kickback, I'm just thoroughly impressed with how well they work. Professionals like Ron Fournier and Kent White (the tin man) use them routinely.
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