[ozarkwelding]

Tacking thin/sheet metal. New to the forum and trying to tack thin (.040-.060) sheet metal. I have a lift tig machine so no HFS and am attempting to tack thin sheet metal for tjoints. My problem is 4 out of 5 times by the time I can get a puddle on the material heat sunk to the table I blow through the piece not on the table as soon as I move the arc to the joint. I'm using 1/16th tungsten ground sharp and one amp per thousandth. If all the stars align and I am able to get a tack once I get moving things are fine. Open to suggestions. I have tried backing up the piece off the table but still blow through the edge.

[tweake]

there is a few different ways but one main one is to have perfect fit up. the better the fit the easier it is.
then blast tack it (jody has video's on it). use high amps, tap the button or stomp the pedal. do not wait for a puddle, if you see a puddle your to slow and to cold.
if you have gaps there is other ways like starting off the side and washing over, or using the filler as a heat sink, or even starting on the filler.
i did some 0.8mm stainless using 1.6mm filler by starting on the filler and washing over.

[ozarkwelding]

Thanks. I tried on some 3/64th sheet metal last night. Cranked it up to 100 amps used a #4 cup and 5cfh of argon. Tilted the cup to touch the tungsten jammed the pedal and lifted the tungsten and almost immediately let off the pedal. Kept a super short arc. Worked great and a tiny tack was born. HAZ went from a huge 3 inch diameter ring with gaping holes to a HAZ of about the size of a piece of rice. I love learning. I have the weldmonger gas lens kit and its great. There is definitely a learning curve to sheet metal. Thanks again

[cj737]

Glad you got that technique sorted out. May I ask, what is the sheet metal’s intended use?

The reason I ask is when you go to actually weld it out, you’ll either need filler or autogenously weld it and need to pulse the arc (you stated the machine you have does not have HF so likely it does not have pulse) so pedal pumping will be needed. This will be another new trick to learn

[ozarkwelding]

Its basically being used for the scrap bin. This welder (Omnipro 220) has a ton of downsides, no HFS, DC only, really no tig options. I really needed a decent MIG/stick welder and never really planned on even using the TIG function, until I did and really liked it. After Im able to repeatably lay some decent beads I'm going to get a TIG only welder so I have AC ability. Im kinda leaning toward a Primeweld 225.

[cj737]

That Primeweld is a nice box, especially given its price. It does have pulse too.

Before you scrap that sheeting, practice laying a weld bead along the seam without filler. Set your amps to 65. Light up, floor the pedal, off the pedal, move the torch one dabs worth, floor the pedal, off the pedal, move, repeat. You’re stomping the pedal to get max amps just long enough li,e you tacked, but not entirely letting off so you don’t lose your arc.

I think Jody did a video recently about pedal pumping in fact that might explain the technique a bit better if you watch it than read it.

[ozarkwelding]

I have watched his pedal pumping videos. Guy has some serious skill. I told my wife the other day that he could look a weld joint, run a few dry runs, close his eyes and weld the joint better than I could with my eyes open.