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Tig Brazing or Oxy Acetylene Brazing?
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TigWeldor70
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    Thu Oct 10, 2013 7:06 pm

A friend of mine and I are considering fabricating a mountain bike frame out of.035 wall, 1" to 2" diameter 4130 or 4140 chromoly tubing. We noticed the frames that are not TIG welded are brazed, probably with an oxy-acetylene set up, and we were wondering if Tig brazing would be effective? If so, would you use AC with silicon bronze? What filler rod size, AC balance, Amperage and Hertz would you recommend? Have any of you tried this application or any others? Thanks for any help.
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I believe you can use either DC or AC with Silicon Bronze, AC will sometimes give a cleaner looking bead due to the cleaning properties of that process. I have not done enough Tig brazing to be of much help on any of the other settings.

Pete
Pete



Esab SVI 300, Mig 4HD wire feeder, 30A spool gun, Miller Passport, Dynasty 300 DX, Coolmate 4, Spectrum 2050, C&K Cold Wire feeder WF-3, Black Gold Tungsten Sharperner, Prime Weld 225
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    Thu Jan 24, 2013 6:44 am

Torch brazing is the way to go. You don't get much of the capillary action that draws the bronze into the joint and creates an internal fillet with tig brazing.
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zank wrote:Torch brazing is the way to go. You don't get much of the capillary action that draws the bronze into the joint and creates an internal fillet with tig brazing.
Ageed, 100%, from a completely different industry.

I regularly silver-braze stainless to red brass, and oxy-fuel is the way to go. I'm usually doing this to fix a failed "tig braze". It's a PITA, as I have to separate the joint, clean it, and start over.

Steve S
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TigWeldor70
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    Thu Oct 10, 2013 7:06 pm

Thank you very much for your help and information with this question. We just haven't seen any bicycle frames with an exposed TIG BRAZED weld and were wondering if it could be "safely" done. It just looks really cool but don't think we will go there if it will just fail.
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    Wed Aug 06, 2014 12:48 am
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Hi tigweldor70

All good advice above. Flame is a better way to go, and what Zank said, 'cause he's da man when it comes to bicycle frames!
EWM Phonenix 355 Pulse MIG set mainly for Aluminum, CIGWeld 300Amp AC/DC TIG, TRANSMIG S3C 300 Amp MIG, etc, etc
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Bill Beauregard
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    Thu Jan 24, 2013 9:32 pm
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Am I wrong? Before Mike got into TIG were his brazed joints socket fit. Brazed joints are strongest where they join larger surfaces together. In refrigeration, or plumbing no joint is ever butt fit. Great effort goes into male/female joints where wide surfaces are mated then joined permanently with either braze or solder.
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