Intro and tigging .035 Al ?

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New to the forum but not new to welding. My name is Scott and I do high end auto restoration for a living.Now for the question. I have my 3rd aluminum bodied race car coming up for a restoration. In the past we have sent the other 2 out to have the welding done as I didn't have a decent tig machine. ( Had a P&H 300 amp AC/DC BEAST no good for thin stuff) That has now changed with the purchase of a Synchro 200. I will now be doing all of the welding on the AL cars to have a better quality control (long story )ANYWAY the car in question is .035 skin. My tig experience with aluminum has been limited to heavier gauge, (1/8 " ) and I am looking for any experience and tricks for working the thinner gauge sheet. Past issues on these cars have been with poor fitment by our welder + warpage.I have been told by my machinist that a helium mix will be better then straight argon. He claims the helium will puddle faster and have less chance of warpage. Obviously my goal is as small a bead possible and little warpage. Any input on this or other suggestions would be greatly appreciated.Thanks much, Scott
Reply:Originally Posted by scotty bNew to the forum but not new to welding. My name is Scott and I do high end auto restoration for a living.Now for the question. I have my 3rd aluminum bodied race car coming up for a restoration. In the past we have sent the other 2 out to have the welding done as I didn't have a decent tig machine. ( Had a P&H 300 amp AC/DC BEAST no good for thin stuff) That has now changed with the purchase of a Synchro 200. I will now be doing all of the welding on the AL cars to have a better quality control (long story )ANYWAY the car in question is .035 skin. My tig experience with aluminum has been limited to heavier gauge, (1/8 " ) and I am looking for any experience and tricks for working the thinner gauge sheet. Past issues on these cars have been with poor fitment by our welder + warpage.I have been told by my machinist that a helium mix will be better then straight argon. He claims the helium will puddle faster and have less chance of warpage. Obviously my goal is as small a bead possible and little warpage. Any input on this or other suggestions would be greatly appreciated.Thanks much, Scott
Reply:Scott, I don't think that using helium is such a good idea. Helium is harder to get an arc on, and is generally used for getting better penetration. I think you are gonna get all the penetration you want, and more... with .035. I have the Lincoln invertec, so we are on basically the same machines. Here is what I have found for thin material. 1/16 tungsten. >035-045 al. mig wire for filler, or 1/16. Set the frequency a bit lower than you may for 3/16 al. Try between 55-75 HZ. I like it, because the arc spreads, and grabs more material in the pool. It makes a flatter bead. I would say clecos or clamps if you can would be a must. And, try to use a backer behind the weld areas. A slab of copper would probably be best, but a steel piece, maybe you'll have to heat and bend some 1/4" steel to fit the panel shape. You'll need a backer to keep the puddle from falling out. Also, a backer fit up snugly will let less air in back of the part, so backpurging won't be an issue. Finally, spot weld it. Set upslope to 0, set downslope to 0. As you hit the pedal, get a puddle formed, drop a dab in, and shut off the pedal. Amps down in the basement, 5-10.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:So much mis information. WOW !You do not need to buy a helium gas mix.Helium is used on very thick sections. Helium gas is used to INCREASE penetration.Just use straignt argon.I hope you have water cooling because you will need it..035 aluminum is VERY THIN. To weld a car body you may need MORE than 200 amps.I know that sounds incedible but here is the problem.When you weld a car body made with aluminum the entire body panel heats up and aluminum gives off its heat very fast, and a large area of sheet metal can give off a lot of heat. I used to do that kind of work and it took a 500 amp welder! Like I said the large surface area of the body panel gives off a LOT of heat!!There is another problem too. Older car bodies have been sanded and painted usually and the body is not always the same thickness because of the sanding that has been done on it..035 takes a lot of skill. I spent 11 years welding .049 stainless and that is not easy and aluminum at .o35 thickness is going to be worst.You can try it, but maybe some copper heat sinks around the weld area may help.The whole body panel will get VERY hot and can burn wiring or rubber or ANYTHING inside the body panel so that is something to consider also.For .035 you will need a 1/16 tungsten.But as soon as you initiate an arc it CAN just melt a big hole before you get to do anything. Aircraft sheetmetal guys also work with some stuff like this too. but they use patches and flush rivets.Last edited by Donald Branscom; 03-02-2008 at 03:15 PM.
Reply:Originally Posted by Donald BranscomSo much mis information. WOW !Aircraft sheetmetal guys also work with some stuff like this too. but they use patches and flush rivets.
Reply:Thanks for the feedback guys. The car in qeustion is an Alfa Romeo GTA. Clecos are am absolute must to me so that is no issue  Makoman I actually bought one of the Meco torches a few years ago to fix a couple of spots on the last one I did and it drove me nuts. From what I could gather these cars were made from a "mutt" aluminum. Apparently the Italians were taking whatever they could grab to melt down and build the cars. I talked to one of our customers who is a long time Alfa nut and he verified this. I have a couple pieces I saved from the last car to play with so at least I won't be taking the learing curve out on the actual job I did go ahead and buy a 1/16 gas lens setup since the machine only came with a standard 3/16 rig FWIW I'm also building a BMW cafe racer for myself using some old street signs to make my rear seat and fairing. Yup more mutt metalThat's the GTA behind my bike Attached Images
Reply:Wow, misinformation indeed. You will not need 200 amps to weld that, in fact 200 amps would burn up that little 1/16 tungsten fast, and will even do a number on 1/8. You will be under 160 amps and for thin stuff a water cooler isn't necessary. You will only need a water cooled torch if you are sitting a a table fabbing up part after part.I have welded 6061 aluminum up to 3/8 thick on 165 amps. Thats maxing out a 1/8 size tungsten. You are welding on some pretty thin material, so expect some warpage.Bill
Reply:Yeah I don't really understand that 200 amp comment. I'm figuring somewhere between 30-60 amps tops ? I'll play around with the scraps I have and see what works best. My uncertanties about the helium have certainly been answerd though.
Reply:Any thoughts on using the pulse feature? I have never used it before but it certainly seems to be ideal for my application .
Reply:In this case, pulse may help if you have used it before.  I use the old standby.  About 125 amps for 1/8" so you should need about 35 amps for .035 plate.   Pure argon for sure.  Helium is to increase the arc voltage which increased the heat.If you are going to use pulse, try 5 amps background (just enough to keep the arc going) and maybe 40 to start with and let your foot do the rest.  Anywhere between .5 and 1.5 hertz.  50% to 60% welding current.  As far as frequency, it depends on how wide you want the bead.  Higher frequency will make a narrower bead.Practice on some .035 plate before you do the real thing. Try to get the heat so you can move right along.  If you dilly dally, its when things get too hot and it all falls on the floor.  Done that many times You know to CLEAN it well.The heck with the car, what model is the beemer?  I have an R76/6 with 110K miles on it.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:i've done a fair bit of Al coachwork but not had the pleasure(?) of working with bodywork this thin.'mutt' alloy aside i don't see this needing different techniques from normal coachwork. Distortion is going to occur during welding to some extent regardless. It's easily corrected as long it isn't ignored for too long (Think about the state that a piece gets in when roughing out into a sandbag prior to planishing/wheeling- you've got to make it 'worse' to move forwards) I'm sure you already now this but, make patches a 'daylight' tight fit. Generous radius at corners of patches, no sharp corners! Lots of tacks, dolly out distortion as it occurs until the patch is fully tacked- at least every inch. No long beads, skip around/backstep when final welding. TIG and O/A both have their pros and cons but I would be leaning toward O/A for this job, especially if it's a poor alloy. In my experience purging Al isn't going to be night and day- only flux will deal with any oxides, purging just prevents further oxides forming.There's a few metal shapers around that use backing tape rather than a purge (Fay Butler is one). It's not cheap but a LOT quicker to set up than an argon purge on sheet metal and would be offset against the cost of argon (were you to purge).Pulse may help (not a fan of it on Al) but again, it's not going to be 'night and day'. Some distortion will occur regardless but anything you do to reduce the heat input will make the weld slightly harder- consider how easily an O/A weld planishes out
Reply:79 R65. /2 headlight speedo combo, clubman bars, bar end signals, "homemade" al. seat pan and rear fairing, probably keeping the mirrors that are currently on it. Once I get the wiring harness done I'll be tearing it all down to powder coat the frame, glass bead the engine, paint tin, coils etc. Something for myself for a change. I got really tired of building cars for everyone else and not having anything of my own to show off so I got this to do quickly, and I have several cars I'm slowly working on for myself and one for my dad More projects than I know what to do with and still looking for 2 more to complete my evergrowing stable.Eventually I would like a R90 or 100 engine for the bike
Reply:Hotrodder the problem I had with the Meco torch was I NEVER got a puddle with it ! Should I have or does gas welding al  not produce a puddle. I would wire brush with the torch lit, immediately put the heat to the panel and while I waited for it to puddle it would just drop. I finally got it to where I would just start adding filler right before I knew ( time wise ) it was about to drop, never saw any signs of a puddle
Reply:Originally Posted by WHughesWow, misinformation indeed. You will not need 200 amps to weld that, in fact 200 amps would burn up that little 1/16 tungsten fast, and will even do a number on 1/8. Bill
Reply:Originally Posted by scotty bHotrodder the problem I had with the Meco torch was I NEVER got a puddle with it ! Should I have or does gas welding al  not produce a puddle. I would wire brush with the torch lit, immediately put the heat to the panel and while I waited for it to puddle it would just drop. I finally got it to where I would just start adding filler right before I knew ( time wise ) it was about to drop, never saw any signs of a puddle
Reply:I'm in Va where are you. I sure would likt to be able to use the Meco. I feel like it was wasted moneyI welded some steel with it with no problem, got a puddle and all. Mag in the Italian alu makes sense too. that would explain the less tha stellar appearance of itt when sanded.
Reply:I have tried material this thin with a mig and found that I did not have enough control of the arc. It will take some finesse for this.Bill
Reply:Originally Posted by scotty bI'm in Va where are you. I sure would likt to be able to use the Meco. I feel like it was wasted moneyI welded some steel with it with no problem, got a puddle and all. Mag in the Italian alu makes sense too. that would explain the less tha stellar appearance of itt when sanded.