Mig vs Tig welding of stainless steel

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Hi all !  Sorry for the long break between updates but I’ve just been so busy getting ready for my move … Fixing , organizing, lifting .. I haven’t had time to weld on the gasifier any further. 

Although I could have a significant portion of the build complete by now (if I could have contained working as I was preciously) if I hadn’t been interrupted by code enforcement.  The time away from the gasifier build has given me a different perspective on my progress thus far.

For example .. I struggled for a long time trying to figure out what was the best method to weld the 20 gage stainless sheet metal.  I first considered  using my oxy-acetelyene torch but quickly found this too be very difficult.  In order to get a decent weld bead you had to heat the metal too long which distorted the sheet.

Next I decided to buy / try using a big welder (everlasting  pp256) which has a steep learning curve but eventually I was able to create acceptable welds albeit at a sloooow pace. 

Back in December I temporarily purchased a Hobart might welder during the time my tig machine was broken. I attempted to weld the stainless with poor results. I then returned the welder and decided to use the Tig.

Well during my move I had to purchase another Hobart might welder to some repairs to my pickup (I needed to weld in some tight places a Tig torch/filler rod just wouldn’t fit.

During this project I realized how much Faster the mig can weld compared to the Tig. I started thinking .. If I could only use this to weld my gasifier I would be done is 1/4 the time!

So I started researching how to best might weld 304 stainless steel… It turned out my failed weld attempts in December were due to incorrect shielding gas selection and too large of a wire. The capabilities of these Hobart machines are such that welding 20 gage stainless is on the edge of what it can handle. In order to weld stainless sheet this thin you need to use the smallest diameter might wire (.023″) which will greatly reduce heat input and therefore warping of the sheet. Additionally the shielding gas I used in December was 75% argon 25% CO2. Apparently this can work for one pass welds but it is much better to use a tri-mix gas of 90% helium 7.5% argon and 2.5% co2. This will greatly improve the quality of my stainless steel welds!

So I have decided to try might welding this stainless steel one more time:) . I have found a welding supply house that can squire this specialty gas for me, so once my move is complete I will create a few videos of my success or failure.

I making slow but steady progress on my move and hope to put the house on the market in the next few weeks. Progress is slow but this is because I am doing everything from house repairs to packing and hauling by myself. Now you can imagine why I haven’t had the time or energy to weld. I can wait til this is over and I’m back to my gasifier project.

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1 comment… add one
  • Jay Stuckey

    I normally use pure argon for S.S. and try to flow a little on the backside of the weld in order to minimize crystallization (a small strip of flatbar taped to the inside corner works). Also try to set it up so you are welding downhand (at least 45 deg.) you will have to move fast to keep in front of the puddle. once you get the hang of it, it works very good, I have made many tanks this way. good luck

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