Stick welding stainless steel tube

[oOTomOo]

Hi All,

Hoping for a bit of advice from the gurus. Hopefully this is the right bit in the forum for this question

Bit of background, I'm re-building / cafe racering a motorbike. As part of this I want to make up a custom exhaust system that routes differently to the stock one.

I'm looking at doing this using 38mm stainless steel tube.

Everything I've read about welding thin stainless says I should be using MIG, CO2 / Argon mix, stainless wire, etc. I've priced all this up and by the time I've bought gas bottles etc I'm looking at around the £250-300 mark.

I've never welded before, but I do have the father in laws ARC welder in my garage. So my question is, could I get away with getting some stainless steel rods - if so, what kind, and welding the tube together in sections into an exhaust. Even if it's basically made up of spot welds.

It doesn't have to be pretty, I have a grinder & I plan on wrapping the entire thing in exhaust tape anyway for that authentic 'old school' look, so it's not like the welds are going to be on show.

I just want to know if it would be possible / what the best stick to use would be if so.

If possible i'd rather do it with the tools I have available rather than splashing out near £300 for something I'm probably not going to get a huge amount more use out of once the project is over.

 

[eSCHEn]

Hi Tom and welcome

It depends on the thickness of the material you're welding. ARC (also called MMA) is ideally suited to the thicker materials. What thickness is the exhaust steel going to be?

Have you considered asking someone to do the exhaust for you?

 

[rich r]

Welcome!

Chances are the material you want to weld will be much too thin for MMA, unless you're very good at welding. Realistically once you get below 3mm thick it starts to get harder, and below 1mm really isn't an option with stick welding. There's just too much heat and the line between melting the two parts then fusing or just dripping out the other side onto the floor is extremely fine. Thin metal is far more suited to MIG and TIG where the heat is far more precise and localised.

If you've never welded before you ought to factor in teaching yourself to weld too - some people pick up MMA in a few hours of practise, for others it takes months or years. And to weld something challenging like curved stainless pipes you're going to have to be pretty experienced. I do recommend you learn to use that welder though, it's a very useful skill to have. However I don't think you'll be able to use it for this project.

TIG is really the best form of welding for exhausts, and especially stainless steel. I would agree with the above and see if you can do all the cutting and preparation and then find someone local to TIG (or MIG) it all together for you. I doubt they'll want much money if you've done all the prep work for them, pretty much just their time and the cost of filler/wire/gas.

 

[eSCHEn]

Wise words Rich.

 

[oOTomOo]

Thickness - the stuff I've been looking at is 1.5mm

I've got some mild steel kicking about which I was going to have a practice with, I also plan to modify the rear subframe on the bike (under seat area) which will give me something meatier to work on.

This is the kind of style I'm going for, obviously i'm under no illusion that my welds will be anywhere as neat as this - the whole exhaust will be wrapped anyway.

Getting all the pieces cut to size & mocked up then getting someone to weld it is a good shout though - I hadn't actually considered that.
If I was to do that how do you think I could mock it up? tape the sections, then marker for section numbers & the rotation they join at? would I even be able to spot weld / tack pieces together?

 

[eSCHEn]

You'd probably not be able to tack with that MMA box but you could tape the pieces together and use a few register marks. That way a fabricator can recreate the angles and tack it up properly before welding.

 

[Wendelspanswick]

You would need to be highly skilled with an arc welder to get a gas tight seal on 1.5mm. Sorry to say you as novice would stand no chance, MMA is just not designed for thin metal.
Even trying to tack it together would just make more work for the person who would weld it together for you.

 

[dobbslc]

I'm doing something very similar with a bike and have just bought a tig welder from someone off the forum.
Even with this I won't expect to be able to weld like that picture above. I'll have a good go at it and if it's not right I'll look at paying a tig guru to sort it out for me.

 

[oOTomOo]

I think that question has been well and truly answered then

If I had the sudden compulsion to go out and get something like a Clarke MIG Pro 90 (https://www.machinemart.co.uk/shop/product/details/pro-90-mig-welder) with all the associated bits and pieces for welding stainless, do you think an air tight seal would be achievable after some practice?

 

[dobbslc]

I am thinking of making slip joints for mine, that way I can either use springs to hold it all together or at least have an easier weld on the pipe ie lap joints not butt joints.
But I need plenty of practice first and that will be on mild steel to start with.

 

[Turbo]

If you are going to mig weld that I think you would use a pure argon gas. Argon/co2 mix is used for welding mild steel.

 

[MoreWellie]

do you think an air tight seal would be achievable after some practice?

having made four car exhausts, the last 2 from stainless I can say that all of them ended up air tight. We used a Clarke 150 set to about two thirds and basically welded it with a series of spots as runs had a habit of dropping through, it won't look anything like your picture though but you can achieve gas tight and durability

We tacked it all together in situ and then carried on tacking all the way round once we knew it fitted, not pretty but effective. The Y pipe and box were bought as were the bends

 

[Bill Edwards]

I think that, for the average learner, it ought to be possible to weld 1.5mm with a MIG without a massive amount of practice. The welds won't be pretty though, it's quite possible that you'll feel a need to cover them up!

 

[Tinbasherdan]

If you can get it to bolton I'll tig it up for you

 

[Mr shiney]

Get someone to weld it for you.

 

[oOTomOo]

If you can get it to bolton I'll tig it up for you

Might take you up on that

 

[Tinbasherdan]

I have the gear mate by all means, I'd come up but I don't have the money or diesel

 

[Mr shiney]

Just spent the day doing exactly this. Forgot how much of a tit of a job it is. TIGd it all together. Cut down a end can from a Fazer and then built a custom link pipe and mid section from stainless. Had to press the pipe to a flat section to clear the shock.

 

[Tinbasherdan]

Oooh mt350, always fancied one of those