tri-mix - impossible in a small bottle. SS welding

[petee_c]

I bought some mandrel bends and a muffler and want to fix the exhaust on my Project Miata. The mandrel bends are 409SS.

I've called Praxair and setup and account, but found out they don't supply trimix in a small (say 60cuft bottle).

I called Tri-Arc welding supply, and they didn't lease/rent small bottles of tri mix.

I was led to believe that Air Liquide Canada would supply small bottles to rent with trimix in it. I set up an account with them, and now they say they don't rent small bottles with trimix in it.

The only bottles they rent are between 5-6ft tall and way more gas than I would need.

The exhaust is just 2" tubing, and I may have to cut and join 3-4 pieces together plus fit in the muffler. I've bought a 180,90,60 and 45 bend pieces, plus a 2' section of straight tubing.

Air Liquide says they can rent me a small bottle of the 15% CO2 and 85% Argon.... Not sure if that is better than just buying C25 gas to have at home....

I took about 6-7 evening classes on MIG welding at the local college before COVID shut down the school.

I have a Hobart Handler 120 (used purchase and ancient) at home. Any advice? I need enough supplies to do some practice welds and then the 6 welds or so on my exhaust.

 

[Abeo]

For 409, I'd just use regular steel MIG wire.

However, I just bought this for my 304 exhaust, eager to try it out...
https://www.amazon.ca/gp/product/B00G5GHA7E/?tag=atomicindus04-20

 

[dr_clyde]

I just used a cylinder of 95% argon, 3% Co2 and 2% nitrogen for a big stainless MIG job. Granted, it was on pulsed spray, not sure how it would behave on short circuit.

If I was in your shoes, I would run the appropriate stainless wire with some sort of high argon mix. You need a little active gas, but not much.

Even if you ran C25 gas, use stainless wire.

 

[petee_c]

For 409, I'd just use regular steel MIG wire.

However, I just bought this for my 304 exhaust, eager to try it out...
https://www.amazon.ca/gp/product/B00G5GHA7E/?tag=atomicindus04-20

I came across that too in my research, I've been gathering info on this project for at least a month now....

I'm not sure if my Hobart Handler 120 has enough amps to use that product?

I also only have 0.8mm tips right now for my welder... It is a m6 thread, and I bought these tips off a chinese seller on ebay.... Joys of trying to learn with a 25+ year old welder....

Technically 0.035" wire would need a 0.9mm tip....

My drive roll has 0.030 and 0.035 using the same groove, and a smaller groove for 0.026" wire.

 

[rattle_snake]

I've used stainless wire with C25 for SS exhaust and it came out fine. Try some test welds on some scrap.

 

[MoonRise]

409 stainless?

Use 409 filler (if you can get it ) or 309L (much easier to get ). You want some 0.030" wire, do NOT get 0.035" solid wire as your little HH120 probably doesn't have enough 'power' to properly run the bigger wire (and you don't want/need 0.035" solid 309 to weld automotive exhaust tubing anyway )

https://www.lincolnelectric.com/en-us/support/welding-how-to/Pages/filler-metal-detail.aspx

https://www.twi-global.com/technica...-of-ferritic-martensitic-stainless-steels-101


Miller rep discussing 409 stainless exhaust and the filler selection (at 0:46, for a minute or so, then the shop/fabricator gets to the GTAW welding in this example)

(video is a random one, no endorsement for or against the shop/personnel/welds)

info about stainless steel and welding for your reference

https://www.nickelinstitute.org/media/1854/weldingofstainlessssteelandotherjoiningmethods_9002_.pdf

More info about welding stainless steels (yeah, the name says "brazing" in it, they also produce welding fillers:

https://www.brazing.com/Support/Procedures_and_techniques/StainlessWeldingProcedures.aspx


Can't get a 'small' cylinder of trimix (guessing that may be because of helium supply issues), then see about some 98-2 argon-O2 instead.

https://www.brazing.com/Support/referencetables.aspx#ShieldingGasGuide

More gas discussion:

https://www.lincolnelectric.com/en-...heory/Pages/mig-welding-stainless-detail.aspx

And some more about 'small' welders and stainless, including a few sentences about tri-mix and 98-2 for short-circuit transfer mode welds:

https://www.lincolnelectric.com/en-us/support/welding-solutions/Pages/compact-welders.aspx

pssst, the word of the day for you is "backpurge"

 

[MoonRise]

C25 gas will tend to give more carbon pick-up than the usually recommended stainless steel shielding gases (tri-mix or 98-2), but may (emphasis on may) give acceptable results for non-critical welds when used single-pass only (no multipass welds, that just gives even more carbon being picked up by the molten steel).

 

[snyder]

I just finished my first mandrel bend exhaust kit in 409 stainless. I used 316 stainless mig wire and 75/25 mix. I was happy with the end product.

 

[welder4956]

You can order a 2lb spool of ER409Nb weld wire online at Baker's Gas & Welding. The local welding supply houses did not carry it in TIG wire and the smallest roll of MIG wire available was over $230 for a 30 lb. spool of 0.035"MIG wire. I paid $21 for a 2 lb. spool. A bit more expensive per pound, but I didn't need 30 lbs.

That being said, when I asked the local welding suppliers what they were selling to the muffler shops to weld 409 SS exhaust, they all said ER70S-6 was all they were buying. I wouldn't use it myself because the welds will eventually rust out and crack before the pipe and I was using it on a small airplane exhaust that kept cracking the welds when ER309 was used.

 

[petee_c]

I just finished my first mandrel bend exhaust kit in 409 stainless. I used 316 stainless mig wire and 75/25 mix. I was happy with the end product.

any pics?

 

[snyder]

Here's some pics , I hate putting pics on here, my work looks so rough compared to many here.

 

[petee_c]

Here's some pics , I hate putting pics on here, my work looks so rough compared to many here.

looks good.

I picked up an "Albee Weld" tank with 85/15 Argon CO2 and a 2lb spool of 308L wire today, as well as a hose from the regulator to the welder.

Too cold today to work on it, but I'll start doing some test cuts and welds....

 

[HMCFab9]

Ideally I'd suggest that be TIG welded.
If you aren't able to TIG, could you tack it together & take it somewhere to have it welded?
That might be easier / better than trying to get the right tank for your welder

 

[Jagmandave]

I agree with HMCFab9, tack or even just mark it in place and take and have it tigg'd together.

What are you building?

 

[petee_c]

Jag and hmc....

That is what a sane person would do,

But I'm going to keep working at it...

Definitely need some more practice pieces...

I'm working on this.... 2000 miata with an amateur paint job and a fart can eBay special muffler.... I have a more appropriately sized muffler and going to have it exist in the right spot.... Working from the resonator back....

.... Need help cutting straight with the portaband as well..... My cuts are wandering a little bit..... Although 2nd one was better than the 1st...

Sent from my SM-G950W using Tapatalk

 

[FSrepair&fabrication]

It can also be done with a 3/32 309L rod with stick... Its not easier than mig or tig but easily obtainable for the diy guy. I can weld 2 tomato cans together with stick and it will hold water.