Hi, was just wondering if i could use my mig torch with co2 as a shielding gas for the back of my stainless steel tig welds to save me buying a new flowmeter, some t-pieces and a valve. I dont have many stainless welds to do. Does migging stainless need backing up, or should you use argon for that anyway? Thanks

you need to use argon for backing stainless welds. m.

Ok, is that all types of welding? Or could i just swap my mig onto the argon bottle and not back it up? Just out of curiosity how come MMA/stick welding doesnt need gas? Cheers

the coating on the sticks creates the shield that gas creates on mig.

I have a twin flow meter set up permanently on the bottle, that way it's always there if I need it.

Flow meters are only a tenner and purging makes all the difference to the weld quality.

Go on. You know you want to.

Paul G
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Right, just found one on ebay for a tenner, thought they were more like £30. Got one ordered now. Cheers.

may be a bit late now but what I have done is use a hobby size bottle of Argon (from machine mart) to back gas when welding stainless with my TIG.

£12 a go.

Thats not a bad idea too, what do you use as a nozzle on the back? Can you only weld an inch or two at a time before you have to move the nozzle?

Tack the 2 pieces together.

Plug both ends of the tube you are welding, I usually use masking tape, and make a small hole in one end for the air to escape. In the other end, make a larger hole for you to feed the gas line through, tape it in place.

I use the machine mart regulator for the hobby bottle with some small rubber tube to feed the argon in. Turn the regulator on (about half way) and wait a minute for it to force all the air out and then weld away!

what about sheet metal?

Depends on the job really.

A thick piece of bar with narrow strips on either side, i.e. 6 x 75 with 3 x 25's on top will create a 25 x 3 void for the gas to flow in.
Tack strips on and masking tape to the job.

or.

A slight fold in the center of a thin strip of sheet, and tape to job.

or.

For awkward shapes I tape cooking foil, press tight to joint and then inflate with the argon by blocking the gas outlet hole with my finger.


Years of welding unobtanium have taught me loads of tricks.
I've even welded inside a pyrex glass jar



Cheers
Paul G

great ideas, ill have a try tomorrow. Right what can i find to weld....