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  #21  
Old 11-28-2018, 03:20 PM
crystallographic crystallographic is offline
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Default TIG vs Torch

I posted this about TIG vs Torch on my website years ago:
https://www.tinmantech.com/education...g-vs-torch.php
An old A&P (aviation mechanic school) instructor once told me, after attending my torch class years ago, that craftsmanship was all about "appropriate technology."
Personally, I started with an old Purox O/A set and then took night classes to get trained in TIG and stick.

I bought a stick machine and got good with it, doing overhead welds on fab projects, and also doing cast iron and stainless. I even did 1/16" rod on 20 ga, like the old Italian coachbuilders did. I also do stick on 1/4" aluminum plate. I like using 5P to cut sheet, too.
MIG is nice, when it is needed. I don't mind doing horizontal or overhead with the mig. The mig is aka as the "manure spreader" when used on steel body work, so some care is needed to stay out of that swamp!

I used the TIG a lot before really learning the torch. I bought a new Dialarc 250 in 1981. I like the TIG, for some things. Like titanium. But the Russians gas weld Ti, or did you not know that?

Then I learned the torch.
So now I can cook sanddabs like the old "Spirit of St. Louis" movie, and I make espresso and cam also decant vino with the 02. I cure expoxy, thaw frozen pipes, remove hornet/meatbee nests underground, bend tubing and rod and bar, anneal metals, loosen stuck bolts, remove glued parts, dry paint, bend plastic, melt glass, solder, braze, make castings ... and I can also weld stainless, aluminum, bronze, cast iron, steel, copper, brass, silver, gold, zinc, pewter etc etc. I like the torch. It is quick and handy.
Cheaper to keep the torch, all costs factored over 60 days, with the work I do ...
And having the TIG makes me look cool in my shop.
With my big roaring gorilla helmet ....
My stick welder is a 1942 Lincoln 10HP motor-generator 3phase DC machine - that has FLAT DC. Love that old machine.
.... And a couple of spot welders.
I weld, but I am not a "real" welder.
-end -
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  #22  
Old 11-28-2018, 05:41 PM
RB86 RB86 is offline
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Quote:
Originally Posted by RockHillWill View Post
Just to add one of my limited experiences with a problem with MIG welding. Prior to getting acquainted with gas welding, I restored a December 1931 Model A pick up with the then new style steel roof. It had very bad drip rails on both sides. The restoration shop that I used had a P9, a fabricated wheeling machine and an Eckold. I thought this was the shop to use, but as I got more into the restoration, I became disillusioned when they wanted to MIG weld the drip rails to the roof section. I had seen many issues with MIG welding while racing the stock cars but wrote it off to being 'rough service life'. They proceeded to over ride my input, but it turned out very nice. That particular truck was entered in five national events and won all five of them, and I was still thinking I did a good job, but after that fifth event I sold it to a Model A collector who took it to a show in Hershey and won some sort of a national award, but merely weeks later the roof cracked on both sides and the buyer was livid with me and I had to dance like hell to avoid a lawsuit. NEVER again for me! Since then I have paid attention and it very common to see cracks in MIG welded sheet metal welds.

This in only my opinion based only on my experience and observations.
Will Ive done my fair share of sheet metal mig. What happens I've found, when you stitch weld the panels together, basically pulse and overlap tacks in an effort to keep it cool, it doesn't penetrate as well as a fusion weld. Then you go to dress it with the grinder and if you go too far, you can see the hairline joint under the welds.

Then planishing those joints are really asking for a crack. Here's some fenders on a 1950 Willy's truck I'm working on. I widened them 5 inches and then extended them 14 inches. We back the joint with a product called metal to metal afterwards, which dries incredibly strong and is sandable. It's not as ideal as a Tig or gas weld with nice planishing done, but the budget and timeframe didn't allow me much time to take it to that level.

IMG_20181128_120313315.jpg

IMG_20181127_114011463.jpg
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  #23  
Old 11-28-2018, 07:47 PM
AllyBill AllyBill is offline
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I often hear of people having trouble with ali tack welds cracking using TIG but it's a simple problem. TIG allows you to do them so much quicker than with gas so soon as you come off the heat the weld you just made is quenched by the surrounding metal making it hard and stressing it as the material contracts fast. No surprise it then cracks. Where gas has the advantage in this scenario is in the time it takes to bring the job up to temp and the resultant heat soak.
Solution - take a little time, put some pre-heat in and let the tacks harden under the flame. Then you can use the propane torch you use for your pre-heat for all your soldering, brazing and heating your food.

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  #24  
Old 11-29-2018, 01:40 AM
Stretch Stretch is offline
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Quote:
Originally Posted by crystallographic View Post
The old-school master craftsmen builders who use the TIG-tacking, use it prior to gas welding the panels. Guys like Jim Hume, Phil Remington, Tom Hanna, Don Edmunds, Don Borth, Dick Troutman, Nye Frank, etc etc.

Maybe the new guys are doing load tests on tack welds ... and this is not making any sense to me.

Good techniques can be misused / misapplied.
Hi Kent. Why would they tack with Tig prior to gas welding? Surely that's counter productive in terms of time taken etc? I'm curious as to what would the benefit be?
Thanks, Matt
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  #25  
Old 11-29-2018, 07:20 AM
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RockHillWill RockHillWill is offline
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Stretch, from my own practical experience I have decided to use the TIG to tack prior to gas welding. I fabbed up some .060" 3003 aluminum pieces for a Model A speedster that I am building before I was exposed to much in the way of gas welding. When the panels had been fit, we TIG tacked the panels in place for ease of movement until we could weld each of the panels. I then started to be interested in gas welding, so I went ahead and welded the TIG tacked panels. At first I had a little trouble when I encountered the proud of the TIG weld, but once I learned to first dress down the TIG weld the gas welding went quite well and the gas weld annealed the TIG tack as the welding proceeded. I have additionally learned to use the TIG weld to tack in a manner that does not build up any proud and it has significantly reduced my set up time. Also, I was having trouble tack welding using gas welding, so the TIG made that easier for me as well.
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  #26  
Old 11-29-2018, 09:40 AM
Stretch Stretch is offline
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Thanks Will. That makes sense. I've never gas welded over Tig - I might just try it for a gas.
Cheers, Matt
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  #27  
Old 11-29-2018, 12:20 PM
crystallographic crystallographic is offline
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Default TIG tacks - why? for gas welding?

Quote:
Originally Posted by Stretch View Post
Hi Kent. Why would they tack with Tig prior to gas welding? Surely that's counter productive in terms of time taken etc? I'm curious as to what would the benefit be?
Thanks, Matt

Radius joints are notorious for holding/clamping/restraining while tacking. Rolled strips of scrap can help but then there is the clamping .... and the weight of the clamps, the bulk, and three hands to do it ... non-starter for tanks, fenders, dash installs, etc etc.
Since the TIG cup can press down for the tacking moment, it is also self aligning on the radius joints.
Tacking by fusion is brief and only needs to hold for subsequent gas welding.
Otherwise, it can be a tough process as both aluminum edges expand in 4 directions when the heat is thrown in .... both edges going up or down independently and mostly never going together.
RSK dash 01322_n_17akygewna1211.jpg
I really had to fight to get this RSK dash tacked in. On the next car it was a snap with the TIG-tack method, learned from my new helper guy - who had built for Prudhomme and had also worked with both Jim Hume and Nye Frank ...


BTW - all the drag and salt tanks are gas welded. And many other race aluminum tanks - with the builders traditionally never leak-testing.
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  #28  
Old 11-30-2018, 02:11 AM
Stretch Stretch is offline
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Thanks Kent. Great info - much appreciated 👍
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