Any advice on aluminum bar to pipe tig?

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Hello,First post.New to aluminum tig.A friend of mine asked me to weld a part for his sand rail. It's a piece of 6061 1" aluminum pipe about a foot long for a radiator pipe connecting 2 radiator hoses. I need to tig a 1" X 1 1/4" X 1/4" thick 6XXX flat bar to the side of it so I can drill it out and install a thermo-switch for fan control.If you look down from the top of it it would looks like this   OI.As I said I am very new to aluminum tig. I am using 3/32 pure tungston with a balled end - miller syncwave 200 at 75 amps (any lower and it won't puddle the bar very well) - balance at 3.5 - pure argon at 18 cfh - 3/32 4043 filler rod (because of the service temp higher than 150 and the vibration). The tungston is at the right stickout - have good heatsinks.The pipe is about 1/16" thick and the bar is 1/4". I am having a heck of a time filling the valley between the bar and pipe without blowing through the pipe.I can get the pipe to puddle, I can get the bar to puddle, inserting the filler rod results in it becoming a big ugly contaminated ball probably due to the fact that I can't get both the pipe and bar to puddle evenly to allow a good situation for the rod to melt into. The gap makes it tough to keep a tight arc on the pipe AND the bar evenly (if you angle the torch more toward the bar (obviously), when you try to get it down in the groove the cup hits the bar and pipe and pulls the tungston to far away creating a huge arc and all it does is heat up the whole thing and you know it's all downhill from there.Signed,frustrated.I'm pretty sure it's lack of experience that is playing a big role in the difficulty of the situation.psI tried to use 2% (red) sharpened but that was worse than the pure balled. Any advice would really be appreciated.ThanksLast edited by CJ38; 07-29-2013 at 11:45 AM.
Reply:Your joint setup is fairly difficult. I'd suggest you try and rearrange things to eliminate the "V" if possible. A big gap increases the difficulty in trying to get the two to puddle at the same time.A few ideas. Take a chunk of flat bar and cut a circle in it with a hole saw to match the OD of the pipe. Then cut that in half and use those pieces to support the pipe and then weld the supports to your flat bar, or make the piece long enough so you can bend the flat to form the bracket. 2nd thought is that you need to fill in the area between the pipe and the flat 1st. You might be able to simply run a few beads on the plate 1st to build up the plate, then weld the tube to the beads you ran. You might need to add some larger "filler" like a piece of 1/4" or 3/8" round stock to the plate 1st and then weld to that. One of these would be the way I'd try to go at this problem 1st, vs just trying to fill something that big with thin tube.To get deep down in the crevice, a gas lens would be my choice, to allow me to use a long stick out and still maintain good coverage. I'd probably crank up the gas flow a bit higher than normal as well. On alum with my Syncrowave 200, I would use 3/32" lanthanated pointed to reduce arc wander. I'd also have the amps higher than you do. For 1/16" I'd set the machine to about 110 to get the puddle to form fast. 1/4" needs a lot more amps however to form a puddle. 1/4" usually need well over 200 amps to weld well with alum. I'd play a bit with some scarp to dial in the machine, but I'd probably set the machine almost at max to have the most available power at the pedal to form my puddle quickly. The test pieces would let me dial in how far down I could turn the machine to maintain the most control.Part of your issue is alum is such a great heat sink. If you go low and slow, the material sucks heat away from the weld zone and everything heats up. That means as soon as the puddle is ready to form, the whole thing is close to ready to go and it often all drops out at once. With more amps, you punch it and get the puddle to form faster than the material can wick away the heat. You have to hit it and right away start backing down to adjust for the material heating up. With 2 greatly dissimilar thicknesses, you will have to balance having enough amps to get the 1/4" to puddle vs the 1/16" wanting to melt and blow holes due to too many amps. Keep in mind that too much heat is bad for alum as it takes out all the temper from the material and leaves it dead soft. It's not just heat from the engine that does this. If you weld too slow at too low an amp setting, the heat build up from welding will take all the temper out of the material..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:The gap fill with 1/4" or 3/8" rod sounds like the way to go...I never thought of that....great idea. I'll have to do some research on the gas lens thing, I assume it's different than the cup.Also, thanks for the tip on starting the puddle quick with the higher amperage then backing it down....never thought of that either. Aluminum is definitely more tricky than mild steel. (not to caption the obvious) but getting proficient at it is something I look forward to.Thanks for all the advice...I'll let you know how it turns out
Reply:There are two things to look at here. The first is your choice in material. For what you are trying to do the best choice is to find a weld bung in the right size and thread. http://vibrantperformance.com/catalo...1022_1300_1222Summitracing also sells many and there are other places you can look to find different threads. If that is not an option then I would try to find a piece of thick wall tube or round stock you could drill and tap to make your own bung. If the bung is very massive in relation to your pipe you can even grind out a concave on the one side of your bung so it follows the shape of the pipe. This will make your life way easier. Now for suggestions on your current fitup. With a plate as wide as the pipe I would not be trying to weld a large puddle from the edge of the plate to the pipe. I would be in the vee far enough to run a bead less than about 1/4" wide. In fact I would tack the plate on each end where it contacted the pipe. I would then start there and weld around the end of the plate into the vee. Finding how far into the vee you should be welding will be much easier at this point and you should just be able to continue your bead through the vee to the other end. If you need more depth of material for where you are drilling through you can always run a second pass to fill in more of the vee.Lincoln precision TIG 275Millermatic 140 MIG
Reply:That's a lot of work when the part you're fabricating is readily available drilled and tapped with an NPT plug from the mail order places!
Reply:already had the pipe, bar, drill and tap. all we needed to buy was the switch. thanks for all of the advice guys.another question regarding the punch it and back orr method - will a 3/32 pure handle the 200 amp start?
Reply:Originally Posted by CJ38already had the pipe, bar, drill and tap. all we needed to buy was the switch. thanks for all of the advice guys.another question regarding the punch it and back orr method - will a 3/32 pure handle the 200 amp start?
Reply:No 3/32" pure will have issues even at 150 amps. The tech school run 1/8" pure for alum at 150. My 3/32" lanthanated is borderline at around 165-180..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:when i tried the 2% thoriated (red) sharpened to a point it wouldnt get the base hot enough to do anything. did i not sharpen it correctly or is thoriated vs lanthanated a deal braker? because if thoriated will do the job i was doing something seriously wrong. it was acting like i had the amps set at about 25 and a needle-like arc
Reply:Why even bother to weld a piece of plate to the pipe?If all you aim for is to created a thickness sufficient to drill and tap for a temp sensor/switch............why not simply build up a "mound" of deposit metal on the pipe where you intend to drill and tap.If you can carry a puddle, you can build up an area thick enough to drill and tap.And if appearance is a factor, you can always grind, buff, and polish the built up spot to satisfaction.
Reply:Good point. DSW you are probably right about the 3/32, I was thinking 3/16. Or maybe I just haven't been running my machine enough lately lol. Probably want to step up to 1/8" at least. Like I said though it has a ton to do with what balance you are running. Thoriated works okay especially for a brief weld here or there. Welding too hot for the tungsten or for an very long and it will start to split and make ugly welds. Some people do a lot of al with it but I have a feeling after trying lanthenated you would never bother with thoriated or pure again.Lincoln precision TIG 275Millermatic 140 MIG
Reply:What about laying a piece of 3/32" filler in the gap between the pipe and plate before you weld it.Run a few tacks, then weld over it.TA Arcmaster 300CM3XMT 304S22P12 suitcase feederX-Treme 12VSOptima pulserTA161SMaxstar 150STLHypertherm PM45OP setupStihl 020AVP, 039, 066 Magnum
Reply:thanks for all the great ideas guys. ill let you know how it turns out. i think ill get aome lanthanated and give it a try as well.