tig welding sheet metal

[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

[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?

[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...

[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?

[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.

[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.

[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.

[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

[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

[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]

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]

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