Question about "TIG Tacking"

[NOHOME]

I was reading on this site about a method of tacking with the TIG where the tack is made with the current cranked way up and the pedal is just taped for a fraction of a second. Seems to work quite well.

What I am not clear on is whether the tungsten is actually touching the metal?It sure looks like it and with the tungsten stuck out very little it is impossible to tell in the video.

Anyone here use this method that can clear up this one point before I go out and give it a try?

Pete

[dirt_merchant]

Hi

Yea Ive used it but with a thumb trigger instead of a foot pedal.

the tungsten has to be really sharp, clean and close to the metal. It works better if you hold your torch as close as possible to 90 deg to the metal. no filler wire either, no time for that

also your gap has to be nil or youll roll the edges away, burn through and have a hole to fill later. quickness is the key, if you dont get it the first time, let the area cool down and try next to it.

[route56wingnut]

If you use filler and aim at the filler you wont burn through . Just a quick blip on the pedal is all it takes .

[BarryA]

My experience with this is really good.
Fit up (no gap) is key - use timing of the cooling/shrinking of the previous tack to pull the edges together to the next one.
Positioning of torch/tungsten as already mentioned.
Also as with any welding have things as clean as possible and keep your torch in place with a few seconds of post flow - this will keep the tacked area clean instead of bluing, and hopefully prevent a crater from forming, and subsequent hole blowing that will happen if you finish weld using fusion only (no filler).
Post some pics of your results.

[doug_walter2002]

I've watched Jim Hume do it on the alum tanks he builds for John Force, He recesses the tungsten into the cup and puts the cup right on the work piece and just hits the foot pedal and goes by sound. There should be no gap in the panel for this to work.

[bobadame]

Adjust the tungsten so that it is maybe a millimeter above the metal with the cup held against the metal at a slight angle. The slight angle is necessary so that the argon has a way to escape. Otherwise the argon will blow a hole right through the tack. Or you can grind a couple of V shaped grooves at the edge of the cup. With a modified cup you can hold the torch flat against the joint. Zero gap between the sheet metal pieces is important. Hold the torch over the tack for a couple of seconds to keep the tack from becoming contaminated.

[mwilliams]

Here are a few shots of how i set up the tungsten for recessed tacking. I use my thumb nail to push the tungsten just inside the lip of the cup. I don't jack the machine up to do this, i just use normal weld perameters. This is not a no brainer on aluminum, it takes a little feel and finesse to accomplish these tacks and you must have metal to metal contact and the material must be clean.

Steel is much easier to learn on as it really wants to jump together when you do this.

Coincedentaly, i also learned this this method from Jim Hume back in the late 70's.




Obviously you want tungsten up high enough so that it won't contact the aluminum. you also don't want to seal the end of the cup to the material. Rock the cup over slightly to let the argon escape.




the little circular dark discoloration in the middle of the weld is where the parts were tacked before welding.

[Dawai]

I use filler to tack. (old school learned on buzz box)

How would a "stitch timer work" like I used to put in mig welders? It'd throw a consistent timed pulse out. Not as good as a capacitive discharge welder but.. Consistent.

[NOHOME]

Thanks all. I got what I needed: The Tungsten DOES NOT actually touch the metal. That was not clear from what I had researched.

I think from here, as with all things involving welding, I need to go practice . I swear that this welding stuff has more to do with penmanship than any real science!

[weldtoride]

Originally Posted by doug_walter2002

I've watched Jim Hume do it on the alum tanks he builds for John Force, He recesses the tungsten into the cup and puts the cup right on the work piece and just hits the foot pedal and goes by sound. There should be no gap in the panel for this to work.

Thanks for posting. This is one of those simple little things that makes so much sense after you hear or see it, but it would probably take me another lifetime to discover it by myself.