TIG Welding - heat input

[dutch]

Thats a decent welder.  Cant go wrong with Esab.  I use  Rehm, both mig & tig.

Not here to start any kind of dicussion, just my advice.  I dont see why one would want to make short welds and let the metal cool down.
You need heat to make a weld. Heat will shrink metal. Shrinking will cause distortion. The faster the metal cools down, the more it will shrink. ( so never ever use wet rags or air to cool welds! )  If you make short welds, the heat affected area will be uneven and therefor the shrinkage will be uneven, making it very very difficult to straighten the panel.  Ofcourse you will need access to both sides of the panel to get it straight again.

and yes, A/O welding aluminium works great.

[dutch]

Hey Dutch!

Long time!!! Hey since you are talking about welding - what do you think about those pastes folks use to put on the metal to keep the heat down or at least mitigate some of it?

I got a new MIG welder and I'm starting to play with it, although many of my project seem to be Ranch projects since thats where some of my projects are with heavy machinery.

Goed om je te zien!
Bryan

Hey buddy ,how are you doing?  Car turned out schweet!
If it makes you feel good to use those pastes, do it!  Personally I wouldn`t spend any money on it.

[soundcontrol]

Thats a decent welder.  Cant go wrong with Esab.  I use  Rehm, both mig & tig.

Not here to start any kind of dicussion, just my advice.  I dont see why one would want to make short welds and let the metal cool down.
You need heat to make a weld. Heat will shrink metal. Shrinking will cause distortion. The faster the metal cools down, the more it will shrink. ( so never ever use wet rags or air to cool welds! )  If you make short welds, the heat affected area will be uneven and therefor the shrinkage will be uneven, making it very very difficult to straighten the panel.  Ofcourse you will need access to both sides of the panel to get it straight again.

and yes, A/O welding aluminium works great.

I will use the Esab mainly for my plugwelds, trunkfloor and such. Can't wait to test it.

When you gas weld, lets say a long panel weld, do you weld the whole thing without any hammer and dolly work? Is that short break enough to cause the uneven distorsion?

[dutch]

with a long panel, I ""hang" the it with one or 2 vise grips to keep it roughly in position, making sure the starting point it dead on. Then I set maybe 2 or 3 tack welds and check if everything is level. hammer them flat, wirebrush front and back ,ditch the grips and start setting tackwelds always the next one at the edge of the heat affected area of the previous one. I kinda steer the panel to where it sits flat for the next weld when it`s hot. Some speed is key because the seam will open up when heated and close down more than it was before you started welding (shrink.) So what you want is prevent the panels to overlap before the next weld. When this does happen, you can stretch the weld with hammer and dolly till the seam opens up and the panels are flush again.
After all tacks are set, I hammer/dolly the whole thing as perfect as I can, clean in and outside, remove all scale. Get in a comfortable position and test the weld track without welding, just for position and such. Then light the torch and start with no stopping till done. No disaster when you stop along the way but dont if not needed.
Again, this is how I do it, and how know I can get a panel straight afterwards with no/ very little filler. Nothing wrong with other ways if the final result is was you`re after.

[soundcontrol]

Thanks Dutch, I will try to do it like that. The key for me to do a longer nice weld is the comfortable position. I will probably get to it in a month or so.

[dutch]

re-reading my previous post there`s one thing that may be unclear. the first couple of tack welds I spoke of are all at the start position of the weld. Not random along the seam. Also, I don think you need to place that many tacks when you do tig welding because you move a lot faster.
I`ll shut up now... just do it, it`s only metal... 

[soundcontrol]

@dutch , thinking about your advise, I was checking out the room behind the upcoming weld yesterday and there is a stretch were I can not get in with a dolly, there is all those brackets in the way. It's about 45cm (18"), from mid quarter window towards the rear. See pict. Any suggestions what to do there?  From the end of that section to the rear, no problem.

• What I can think of is to cut that piece out, its probably spotwelded on the upside and weld it to the quarterskin, then weld the whole thing back in again.
• Tack welding with a MIG, is that gonna do the trick? I see MCR do that all the time, they say its to avoid shrinkage.
• Make a flange and glue that stretch? (but it just don't feel right).

If anyone has any other better ideas, it will be appreciated!

[ViperMan]

Lol - this thread makes me wanna buy a welder so bad...  I just wanna play with metal - LEGO's ain't cuttin' it for me anymore... 

[dutch]

@dutch , thinking about your advise, I was checking out the room behind the upcoming weld yesterday and there is a stretch were I can not get in with a dolly, there is all those brackets in the way. It's about 45cm (18"), from mid quarter window towards the rear. See pict. Any suggestions what to do there?  From the end of that section to the rear, no problem.

• What I can think of is to cut that piece out, its probably spotwelded on the upside and weld it to the quarterskin, then weld the whole thing back in again.
• Tack welding with a MIG, is that gonna do the trick? I see MCR do that all the time, they say its to avoid shrinkage.
• Make a flange and glue that stretch? (but it just don't feel right).

If anyone has any other better ideas, it will be appreciated!

yea... that is a problem.
- If possible, I would remove the brackets and make room for hammer & dolly, but you have to be able to weld them back in the right location after all other work is done.  Sometimes when there`s no way to get to the backside with a dolly ,I mig the whole thing and lead the area.
-I would not tack with mig. No clue how that would avoid shrinkage. mig = heat and heat = shrink, period.  You will run into several problems when you do. When welding, you will run into the big MIG dots and they will need extra heat to keep the puddle going. That will result in an uneven heat affected area ,thus uneven shrink. Also, when you start stretching the weld you will hit the mig tack welds and since they are hard and thicker than the rest of the surface, you will create distortion which is near impossible to fix.
-Using glue is no option here, unless you do the whole seam.

[soundcontrol]

Yep, a problem it is...but I have seen other weld quarterskins like this, gonna look for those posts (in other forums) and see if I can figure out what they did. Not sure if these brackets are convertibles only. Also gonna try to figure out if I can remove anything there. The space between the panel and the bracket is maybe 4-6mm, maybe I can get a flat piece of steel in there from under, and have the dolly on the other side of the bracket.... (thinking out loud here...). Oh, well, I like a challenge.

[dutch]

you may be able to use a big spoon dolly. 
I think most do mig, beat it somewhat into submission and bondo the remains.

[soundcontrol]

you may be able to use a big spoon dolly. 
I think most do mig, beat it somewhat into submission and bondo the remains.

Yes, got one of those, might get in there, at least in spots.