Tuesday, November 28, 2006

AV - Welding and The Big Lie

> The PHD of Metalurgy hosting the welding Forum at SunFun said TIG is the > best by far for welding 4130 despite decades of published preference for > gas welding. >


This is the sort of disinformation that guarantees the demise of grass roots aviation.

There is no question as to the superiority of TIG. Same for Rolls-Royce automobiles. But those wunnerful friendly experts at all the airshows leave the impression that other forms of welding will produce an airplane that isn't quite as safe. And that's where the Big Lie comes in.

So you do a simple T-joint in tubing with TIG and an identical joint with gas. Then you test them. Let's say the TIG'ged joint fails at 6000 pounds and weighs an ounce less than the gas-welded joint that fails at 5000 pounds. Obviously, TIG is 'best.' But when the 6-g stress in that particular joint is only 1500 pounds who the hell cares? Other than the guy trying to sell over-priced TIG rigs to novice builders.

The Welding Wars are similar to the Glue Wars in that both are usually fought by people who are either trying to sell you something or who have never actually built anything. All of the glues we use are stronger than the softwoods commonly used in aircraft construction. And all methods of welding may be used to produce a strong, safe airframe.

So while the welding guru didn't voice a direct lie, neither did he tell the whole truth.

So what's the whole truth? That depends on you. But you can't answer the question until you've learned to weld... with gas, stick, TIG and MIG. Then you can say "This method of welding works best for my airframe and my shop and my financial situation and my access to resources..." and for all I know, for your sense of style as well :- )

Airplanes call for welding. It is a skill we all should have in our warbag. For certain tasks and components some types of welding are preferred over others but that is not readily apparent to the novice.

Learning to weld with gas involves only a modest investment, most of which may be recovered by selling the rig. But the odds are, once you've learned to weld you'll never get rid of your gas rig, even through you will transfer the skills you've acquired to MIG and TIG.

TIG is great. I prefer it for landing gears, engine mounts, anything made of aluminum and all sorts of 'sit down' jobs small enough to do at the bench, inside the shop. But I also use gas and MIG, often in places were it would be grossly impractical to use TIG.

In the same vein, Rolls-Royce is great. But I drive a 1965 Volkswagen bus and it has somehow managed to carry me from the shores of Arctic Ocean to below the Tropic of Cancer, even though any number of people will insist an old VW bus is not the best vehicle for that purpose.

Airplanes are kinda like that. If you build one and go fly, you'll see that the Glue Wars and the Welding Wars and all the other wars of personal preference are just another waste of time, something that detracts from building your airplane rather than contributing to its completion.


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