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My welding challenge

ducdon

ducdon

Super User
Premium Member
After a long wait I received my Expansion Chamber Kit for my project motorcycle. I am very impressed with the laser cut and rolled sheet metal bits. My big challenge now is to weld it together. I'm not sure if I will use TIG or Oxy/Acetylene fusion welds? The metal gage is #20 (.035) so burn through is a real hazard. I will be getting some 20 gage material and making lots of practice welds with both processes. In the mean time I have taped them together to get a better feel for the fitment.
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I would use TIG with like 20 amps or so. Should not be too bad - just practice for few days. May not look supper through like say done by one of these welders with 10 years experience.
 
Tom Kitta said:
I would use TIG with like 20 amps or so. Should not be too bad - just practice for few days. May not look supper through like say done by one of these welders with 10 years experience.
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I don't think it's an easy question, I don't think he can weld this exhaust pipe after a few days of practice. Because its material is very thin, if it is a little thicker may be feasible, but you should know that the most difficult for the novice welder to manipulate is the sheet welding. I suggested that he should start with other easier welding practices, otherwise its exhaust pipe will often perforate and leak -------------
 
Is that stainless? If so you will probably want to backpurge it, or you will end up with all sorts of sugaring on the inside given how thin it is

Mig wire works well for filler on such thin material, 1/16 or smaller tungsten with make the job easier as well

I wouldn't touch it with oxy/act, that would take a ton of skill to not turn it into a molten pool
 
phaxtris said:
Is that stainless? If so you will probably want to backpurge it, or you will end up with all sorts of sugaring on the inside given how thin it is

Mig wire works well for filler on such thin material, 1/16 or smaller tungsten with make the job easier as well

I wouldn't touch it with oxy/act, that would take a ton of skill to not turn it into a molten pool
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This!

I haven't tried anything like what you are doing but what little I know sats that this is the only way.

Practice on some scrap first you you may have some expensive scrap.
 
Any details on the kit? Is this a prefab kit or did you send the chamber dimensions and they send out the cut and rolled parts?
 
Great looking project. High fun factor!!
As mentioned above - key is practice on similar thickness, shapes and same material.
Also clean - wire brush and solvent clean (acetone). Make sure you get off any glue residue from the tape.
 
van123d said:
Any details on the kit? Is this a prefab kit or did you send the chamber dimensions and they send out the cut and rolled parts?
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It's a kit. Google WTF pipes. The guy is a fan of Kawasaki 2 strokes and makes the kits as a side gig. It does take awhile from order to delivery.
 
I thought there was a coating that can be put in the inside to stop the sugaring.
I had a friend that cut up his exhaust like that to replace the baffle on his bike he was thinking of using one of those torch setups with the mapp gas to stick it together. I welded it with no problem with a Princess Auto welder with tig conversion.

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If you do have some blowholes try lighting up on the filler rod although you may not need filler at all or very little.

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Tom O said:
I thought there was a coating that can be put in the inside to stop the sugaring
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There is a past iirc, it might cause problems when a hole opens up, not sure, have never used it

Back purging is pretty easy, just t off the regulator output, tape all the joints (remove as welding) and tape both ends shut, cheap to, not sure how much that paste costs, but I don't imagine it's to cost effective
 
phaxtris said:
Is that stainless? If so you will probably want to backpurge it, or you will end up with all sorts of sugaring on the inside given how thin it is

Mig wire works well for filler on such thin material, 1/16 or smaller tungsten with make the job easier as well

I wouldn't touch it with oxy/act, that would take a ton of skill to not turn it into a molten pool
Click to expand...
Just plain old 1018 mild steel. I do have some MIG ER70S-6 that I will try for TIG.
 
For something that thin, if you are not confident tig welding it, you could use brazing with an oxy acetylene torch.
 
Chris Cramer said:
For something that thin, if you are not confident tig welding it, you could use brazing with an oxy acetylene torch.
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My opinion: If TIG welding is not confident, the probability of ------ brazing is not too good. Any welding requires a lot of welding practice to improve the technique. Avoiding difficulties is never the right way, but it is always a little too hasty to go directly to welding the sheet with higher requirements. It is low cost to start practicing from a relatively low requirement welding, which is also the process that most welders have to go through. I hope to see a relatively perfect welded exhaust pipe - looking forward to it!
 
Does your tig welder have pulse capabilities? I really liked using pulse on my bicycle tubing, although that was ~0.035" wall thickness.

I'd second using mig wire as filler. Rule of thumb is for the filler to be no thicker than what you are welding, but I don't know if 0.020" mig wire is readily available?
 
I'll say I'd choose TIG inna heartbeat, provided that your machine will dial down enough.

Always just used what filler was on hand, typically 1/16 wire. See no reason NOT to use MIG wire, though, just never did...

Get some similar size sheet material, roll a couple tubes, tack them and weld them. Cut out the welds, Roll the tubes tighter, rinse, repeat! Practice, and the results that you get, will tell you when to swallow hard, and just get on with it! :)

I was spoiled, while learning, always had a foot pedal, and a comfy chair to use, and a table for my work. May be something to that, as it was very similar to the TIG stations I saw in several different Aviation related shops.
With the machine that will go down pretty low, you can play around and make all sorts of weird build-ups just controlling the heat input and the filler amounts, you can build essentially a 3D printed structure, given enough patience... Pretty amazing what you can do with decent control over your settings. If you don't have the option of a foot pedal or fingertip amperage control, then double down on getting your settings sorted on practice material, set it so you can be moving at a comfortable pace, rather than rushing to try to keep up. Nicely fit up joints need less filler, too!

Suggest you hack together a couple wooden Vee Blocks, of sorts, so you can rest the pipes sections in them to keep them from rolling around on the table or bench. It's a lot easier to get a nice looking weld, if you have the support for your hands, and can work in comfortable positions, rather than having to try to warp your body and hold yer tongue just right, to get yourself lined up on the seam!
 
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