tig welding sheet metal

[nails79]

hi everyone new to the forums and new to tig. i have a new synchrowave 200 and i am currently attempting to fill the holes in the sheetmetal fire wall in my car. the gauges range from 18-22. i have adjusted the amps from 10 to 35, tried the pulse feature (no luck??), im using 2% tungsten size .040, 1/4"-3/8" cup, argon set at 20psig with 3 second post flow. having a lot of difficulty with burn through. just wondering where i should set the machine up for this size material. am i on the right track?? any tips for a beginner?? i have gotten a decent grip on thicker material 1/8" and thicker. thanks in advance for any advice.
matt

[jamscal]

I think your gas flow is too high for starters.

You don't say how big the holes are. How big are they?

Try backing up the holes with some copper before welding. Get something heavy to lean up against the inside of the holes to hold the copper there.

I slit copper pipe and flatten it out with a hammer to make copper backing strips. Heat it up w/ your tig torch and let it cool down. It'll be very soft and bend to any shape.

Make sure the metal is clean. Start the arc a bit from the edge and move in, watching everything carefully.

You might practice by getting some sheet metal and drilling the same sized holes in it, and go from there.

Good luck,

James

[nails79]

the holes i am trying to fill with just filler rod are 1/4"-1'2". anything bigger i am cutting new metal and attempting to weld in. what should the gas be set at? i will definitely try a piece of copper behind the welds. thanks

[jamscal]

A 1/2" hole is pretty big. You should probably cut some metal to fill that.

Depending on what you're doing, you could just back up the hole w/ sheet metal and weld it, then skim w/ filler before painting.

I'd go down to 10 cfh on the gas.


-James

[HMW]

Filling a 1/2" hole in 18-22 ga sheet metal takes alot more practice than say a piece of 1/8". No room for being to hot Your going to need small filler as well. sometimes I just pull some off the mig. .035" and use that. It woudl be easier to cut a small plug and weld around it. Good luck and welcome here

[jwsrep]

I think the best advice has already been given. Cut some sheet metal to fill the 1/2" holes, and on the smaller holes I like the idea of a backer material. Just for the record 20 CFH (not psig) is not too high for TIG. In fact I wouldn't go much lower. Normal TIG gas flow ranges are 15-25CFH for argon and higher (35-45 CFH) for helium or helium/argon mixtures. This is ofcourse with standard collet body/cup set-up.

Let us know how you make out.

[phila.renewal]

Ditto on cutting a patch to fill that big a hole.

In terms of trying to do it anyway, here's what has worked for me.

Start your puddle near but not on the edge of the hole and dip immediately. This will give you some material to work with to cool and control the puddle and you can work your way around the hole, dipping the filler as you go, without making the hole worse.

[nails79]

thanks for all the replys, what i am noticing now is mostof the burn through occurs when my torch starts having an erratic arc. the torch begins to pop like a machine gun??? all the metal is clean, clean tungsten, good ground, what causes this? thanks.

[Samurai Dave]

Long arcing?

thanks for all the replys, what i am noticing now is mostof the burn through occurs when my torch starts having an erratic arc. the torch begins to pop like a machine gun??? all the metal is clean, clean tungsten, good ground, what causes this? thanks.

How far away from the puddle is the tip of your tungsten?

[BWS29128]

thanks for all the replys, what i am noticing now is mostof the burn through occurs when my torch starts having an erratic arc. the torch begins to pop like a machine gun??? all the metal is clean, clean tungsten, good ground, what causes this? thanks.

Along with Dave's question, are you getting good flow with your sheilding gas? Is your collet or collet-body clean? Are you sure you've got a good clean connection with your work-clamp?

I think 10cfh is probably a little low, even for an indoor windless environment, but then again I don't have tons of experience with sheet as thin as you're working with. I just finished a bunch of 1/4", 1/8", and 1/16" sheet work and kept my flow at 15cfh the whole time, except for the two times I was outside and had a little 5kt breeze blowing where I increased flow to 20cfh.

My only other suggestion for your "popping" sound, and Rich-The-Jackson-Rep will be able to answer this a little better, is: are you sure you've got good quality tungsten? I recently picked up a couple of sticks of 2% Thoriated from my LWS that wasn't in very good shape....have you swapped out tungsten or considered going back to your LWS and getting some new stuff?

Also, and there may be some disagreement here, but have you considered moving up to 1/16" tungsten?

And one last thing and then I'll shut up (I swear!): I really don't have any experience with auto sheet metal, but isn't that stuff coated and electrically treated at the factory? Even if you've got it super-clean, there may be some type of adverse chemical/electrical combination going on...and MAC072 or Sundown (George) is going to need to answer that (or maybe Aerowelder if he's around). You didn't say which 2% you're using...? Have you considered trying 1.5% Lanthanated or 2% Ceriated tungsten? I just picked up some 1.5% Lanth the other day and have already found a new use for it! (Overhead aluminum!!!).

Okay...I'll hush now.

PS: If you find a solution or a combination that works, let us know please...

[BWS29128]

My only other suggestion for your "popping" sound, and Rich-The-Jackson-Rep will be able to answer this a little better, is: are you sure you've got good quality tungsten? I recently picked up a couple of sticks of 2% Thoriated from my LWS that wasn't in very good shape....have you swapped out tungsten or considered going back to your LWS and getting some new stuff?

Also...how are you grinding your tungsten (sharpening it)? Is it possible that you're contaminating it on your grinding wheel?

[nails79]

the tungsten is 2% thor......(however you spell it) red, argon set at 20cfh, the electrode is approx 1/8"-3/8" away from the work piece, the tungsten is sharpened to a pencil like point on a gringing wheel i have that is only used for the tungsten. i believe it is my ground, i grinded and stripped away the paint on the frame rail of my car for the ground. i noticed this yesterday when practicing on scrap, clamped ground right to work piece no issues with arc. i know its just going to take alot of practice. should i use a bigger cup to help cool more of the material??? or stick with the 1/4-3'8" cup i am currently using. thanks

[jamscal]

I do a bunch of short welds on square aluminum tubing coming together at all sorts of angles.

I get popping because of turbulent gas flow I think. At the edge of the tubing I'm trying to shove the filler in, the arc burns off my filler too soon and it'll keep popping as long as I try to put it in. I have to then change angles.

-James

[BWS29128]

Let's Try This

the tungsten is 2% thor......(however you spell it) red, argon set at 20cfh, the electrode is approx 1/8"-3/8" away from the work piece, the tungsten is sharpened to a pencil like point on a gringing wheel i have that is only used for the tungsten. i believe it is my ground, i grinded and stripped away the paint on the frame rail of my car for the ground. i noticed this yesterday when practicing on scrap, clamped ground right to work piece no issues with arc. i know its just going to take alot of practice. should i use a bigger cup to help cool more of the material??? or stick with the 1/4-3'8" cup i am currently using. thanks

In GTAW welding, shielding gas doesn't really "cool" the weld puddle...all it's for is shielding the molten puddle from external and internal contaminants. I'm sure there's a miniscule amount of "cooling" that takes place, but that's not the point.

I'm sorry I'm forgetting this as I type, but what type of power-source are you using again? Is it an inverter-based power source or simply a square-wave capable transformer based supply?

Try this and see what happens: grind your tungsten all the way down to a needle-sharp point. Make sure your ground is good...preferably on your firewall as I think the frame may be a little far away and requires the current to travel to the firewall via numerous screws/bolts of varying metallic qualities. Switch up to a 1/2" cup size (about a size 6...which is actually a hair larger than 1/2" I believe). Allow the tungsten to stick out of the end of the cup approximately 1/2". Lay the cup over on it's side on the firewall and adjust your angle so that your tungsten tip is NO MORE THAN 1/16" - 1/8" away from where you're attempting to create your puddle. If you can, pay attention to where, EXACTLY, your arc is contacting the firewall as it comes off of the tungsten. Don't attempt to start your puddle RIGHT on the edge of the hole(s)....since you're filling them in, you should probably start your puddle about 1/4" away from the edge of the hole, add a globule of filler metal, and then--backing off the pedal/amptrol as necessary but keeping the puddle molten--work the molten puddle into and around the hole. Keep in mind that this is where everyone is talking about the benefits of having a copper backing plate: it gives something for your molten puddle to flow into/across without having to worry about the puddle sticking to the backing plate.

Enplck (welding educator) and SundownIII and Aeroweld (and BlackWolf, wherever the heck he is) are much better at this sort of thing than I am and I wish to G_d they'd jump in with their .02 cents...I'm afraid I'm going to start confusing you if I keep going.

Is any of this making any sense to you? Let me know how it's going or if I can clarify anything I've said so far.

~Clint

[BWS29128]

Super-Heated Gas Has To Have SOMEWHERE To Go...

I do a bunch of short welds on square aluminum tubing coming together at all sorts of angles.

I get popping because of turbulent gas flow I think. At the edge of the tubing I'm trying to shove the filler in, the arc burns off my filler too soon and it'll keep popping as long as I try to put it in. I have to then change angles.

-James

James, I doubt your popping has as much to do with turbulent shielding gas flow as it does with air/gas resistance flowing through your square tubing and then "blowing up" or "blowing back" into your puddle and onto your tungsten as you weld your seams closed.

Either try back-gassing your tube (if ultra-clean looks are important) or try drilling a super-small hole somewhere along the tubing to let super-heated air and gas expand/escape as you're closing in your welds.

One of the aerospace guys on here probably has something else that will work but that's a common problem for me when TIG'ing on aluminum tubes in rails or towers or sponsons on boats.

~Clint