Welding using oxy acetaline?

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byron addams
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Welding using oxy acetaline?

Post by byron addams »

is it ok to weld vacuum fitings useing oxy acetaline? I was going to use mig but the gas for welding stainless with mig is stupidly expencive (probebly becauls it contains helium). And i dont have acsess to a tig welder and ive never used tig before. i would use a stick welder but it always ends up a bit messy and i dont want to waist expensive vacuum fittings.
Trying to keep the magic smoke from getting out.
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Nicolas Krause
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Re: Welding using oxy acetaline?

Post by Nicolas Krause »

Hi Byron,

I'm unable to comment on oxy-acetylene given that I haven't used it, but I was able to TIG weld my own chamber. I believe TIG welding is standard for vacuum chambers due to the welds being less likely to leak. I'm not sure if you have access to an oxy torch or if you're welding on your own, but I was able to buy a TIG welder off Amazon for quite cheap, I believe 250$ for the machine. The regulator and tank brought the total for the setup to around 400$ CAD or 250-300$ US. It's not a hugely impressive machine, but it was perfect for the amount of welding I needed to do. With all the videos on YouTube and with a bit of help from the old hands here on fusor.net it took me 3 or 4 practice sessions to get confident and then I was off to the races. It wasn't all that difficult at all.
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Re: Welding using oxy acetaline?

Post by Gustavo Cervantes »

There was a manual on vacuum aparatus construction that mentioned brazing being OK for medium vacuum, i dont remmember how i got to that paper, it is a PDF online.
That being said oxyacetilene welding might very well be another can of worms on its own.
I have seen other guys build diffusion pumps via brazing so i know it works but totally depends on the use.
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Richard Hull
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Re: Welding using oxy acetaline?

Post by Richard Hull »

TIG is the weld of choice for SS in vacuum service. The heat is localized and fast. Thin sections can be mated by brazing, but oxy-acet, just heats a big piece to cherry red if you use a torch and want the braze or silver solder to flow, not nice.

Richard Hull
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Fusion is the energy of the future....and it always will be
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Re: Welding using oxy acetaline?

Post by Frank Sanns »

Stick welding SS is not a good choice. The reason inert gasses are used is to prevent oxidation of the surface and preventing the welds to stick. Oxygen and acetylene can be used to weld and to braze SS provided the flame is adjusted to be slightly carburizing (slightly deficient in oxygen). Not sooty but definitely fuel rich. This means that no oxygen is left in the flame to oxidize the SS.

It is easier to silver braze SS with the correct flux than it is to weld SS to SS. You can find small tips for the torches so the heat is high and localized. As Richard has said, you don't want to heat the entire piece up.

TIG is the choice but in a pinch Oxy-Acetylene will work. Practice, practice, practice no mater which technique you try.

Alternatively, universities often help young people out and my weld or machine it for you.
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Bob Reite
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Re: Welding using oxy acetaline?

Post by Bob Reite »

I only use my oxy-acetaline rig for cutting now that I got myself a TIG welder.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.
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Richard Hull
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Re: Welding using oxy acetaline?

Post by Richard Hull »

In other scientific construction endeavors, I do use my oxy-acetylene rig for small item brazing and silver soldering. (Cutting of course, as well) I rarely use my TIG now that I have my fusor up and running. It is a big Lincoln TIG welder and can also do DC or AC stick welding. I have a MIG welder too, but use it for medium steel assembly and repair (very rare). I pick up a buck or two doing work brought to me for welding/brazing repair. (word of mouth rather than advertised).

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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byron addams
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Re: Welding using oxy acetaline?

Post by byron addams »

thank you for the advice i think i eill go with oxy-acetaline becauls i alreadt have the stuff to do it and im prety experianced from working in a fabrication shop. i was just wondering weather there would be anny outgaging or microscopic holes or anything like that so thank you for clearing that up
Trying to keep the magic smoke from getting out.
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