Back to Basics: DC TIG Welding - Weld.com and Kevin Caron
TIG expert Wyatt "Mr. TIG" Wyatt and artist Kevin Caron talk about and do some DC TIG welding while they cover info helpful to TIG welders .... First Wyatt explains that the TIG welder must be set to DC negative. Kevin talked about how he got into TIG welding when he was creating a large stainless steel sculpture and the MIG spool gun just wasn't doing the job. One of the first mistakes he made was getting the ground and the torch backwards, so it was set on DC positive instead of DC negative.
Wyatt next explains how the TIG torch uses his favorite set up of a gas lens, a 2% thoriated 1/16 diameter tungsten ground to a pencil-shaped point with a stick out of about 1/4" inch so he can see the end of the tungsten as he welds, and a short backcap. Wyatt and Kevin discuss how to decide what size tungsten to use, why how you grind the tungsten matters, and what distance you want the tungsten from the work (\the farther away the tungsten is from the work, the more volts).
Wyatt then says it's best to just start out with bead on plate, no filler - if you don't get this right, you can't improve your welding. So just start on a flat plate and initiate the arc. That brings up the discussion of starts - high frequency start, lift start and scratch start, with the two of them going into detail on each. Next they discuss foot pedals, and how pedals - and thumb controls - are not all interchangeable.
Wyatt explains about the filler they're going to use once they get to that point. They are going to use 347 stainless steel filler rod, which is used a lot in the racing industry. The 347 has chromium in it and a very high tensile strength. For people who are creating lighter work such as art, Wyatt recommends 308L stainless steel filler rod, which you can probably get at any welding supply store.
Before they actually start welding, Kevin goes through each knob, switch and connection on the welder's panel, explaining what each is for.
Now it's time to do some TIG welding! Kevin welds bead on plate, while Wyatt gives a play-by-play, explaining what he looks for in a good weld, while the split screen shows a close-up as Kevin welds. Wyatt recommends doing this 100 times to make sure you have command of the process. Kevin adds that he practices for each project, just to make sure everything is set up properly.
Next Kevin adds filler material. Wyatt talks Kevin - and you - through the process as the split screen provides a close-up of the weld under way, then shows a close-up of the finished weld. Wyatt also explains the "third hand," that helps hold down the piece and provides an extra ground.
Next Wyatt talks about duty cycle and explains the difference between light-duty utility and heavy-duty industrial machines. If you're building your own aircraft or go-cart, a light-duty utility machine is fine, but if you're going to build 100 of them, you want to buy an industrial machine because of the duty cycle, which measures how long you can weld without overheating the welder. Wyatt says an industrial machine he uses frequently, the Lincoln V205, which costs about $3,700, while the utility machine they have been using to demonstrate is less than $900. So if you're building a project, the lighter-duty machine will work, but if you're doing production work, you need an industrial machine.
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