TIG questions

Almost all TIG torches used today are based on the Linde designs from the 1950's.

Airco tried to make a different style for a while, but they are long forgotten now.

So yes they are all the same, except when you get to really small and really large torches. In those cases many torch makers have come up with proprietary designs.

Any gas lens collet body will allow a much longer stickout. A general rule is that with a standard collet body you can have up to 3 times the diamter of the tungsten sticking out past the gas cup rim. With a gas lens you get 6 times the diameter as your stickout.

You can check out the parts at

I find this a bit confusing. Why would I be able to stick out a 2.4mm tungsten 2.4 mm more than a 1.6mm tungsten? The lens part look very similar to me.

I am not questioning the rule, I am just trying to understand: if it is just the gas, it should be possible to mount a small tungsten in a big gas lens (I could use the lathe to turn a special holder) and stick it out much longer.

From looking at torch part, I would have supposed that gas coverage would depend a lot on cup size. Is there some rule for those?

The larger the cup the further you can go outside the cup. As I said the general rule was 3 times or 6 times, but you can go further with a gas lens with the largest gas cup possible. For a #2 series torch that would be a #8 cup (1/2" ID). For a #3 series torch you can go up to a #12 cup (3/4" ID).

Thanks Ernie. We have a Miller Aerowave at work that we use mostly for welding up aluminum molds (fixing "oops"). There have been a few situations where the area to be welded is in a narrow, deep hole or slot. The normal cups we have just can't get in there, and the boss just says he'll look into it for buying smaller electrodes, collets and cups, but never does anything, so I'm considering getting my own.

With these type of welding situations, we either have to "shotgun" the weld (turn up the amps and fill in the whole thing then recut it), or what I call drop welding, you melt some weld rod into the hole, then stick your torch in there and meld it into the walls. Needless to say, neither method works well.

John

Have you thought of drilling the defect and hammering a rod plug in the hole?

Actually, thats exactly what we do in some circumstances. The molds have

3/16" holes drilled in the back so we can drill vacuum holes with #76 drills. If the mold has progressed this far (more often a finished mold that has been damaged), and welding will cause these 3/16 holes to melt open, then thats what we will do.

but most of the time, its a mold thats still being cut. No back drilled holes yet.

Sometimes the backdrilled hole goes off to the side from being too close to another hole, and pokes a hole in a cavity. If the hole is straight, we can plug then weld.

John