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Discussion Starter · #1 ·
Does anyone have any experience with this to share? I did a couple of searches and couldn't come up with anything. I found a bit about brazing with the TIG torch on the internet but couldn't find anything related to bike building. I'm not going to do it on #1, just was interested in learning more about it. Seems like DaveB had talked a bit about it in the past, couldn't remember though.

So what can you braze with TIG? What kind of rod does one use? I assume flux is either not used or is different, dunno. I'd like to know more just to know it I suppose.
 

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I've tig brazed w/ SiBronze but its usually LITTLE joints/fillets. TIG won't generate enough widespread heat to do a big fillet. Thats its advantage in most areas (small HAZ) but a drawback to large bike fillets. You'd probably have to hold the torch a mile off the steel and just go hammer down on the pedal. Might be able to make smaller multiple build passes as an alternative?
 

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Reformed car junkie
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jay_ntwr said:
Does anyone have any experience with this to share? I did a couple of searches and couldn't come up with anything. I found a bit about brazing with the TIG torch on the internet but couldn't find anything related to bike building. I'm not going to do it on #1, just was interested in learning more about it. Seems like DaveB had talked a bit about it in the past, couldn't remember though.

So what can you braze with TIG? What kind of rod does one use? I assume flux is either not used or is different, dunno. I'd like to know more just to know it I suppose.
I asked a similar question on another forum. What i got out of that and some prior experiance with silicon bronze is its not good for anything structrual. So its good for braze on type bits. I use it for cable stops and seat post binders. Anything else gets welded. Low amps help alot.
 

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Discussion Starter · #4 ·
So when you say little, like brake bridge little or even smaller than that? I was wondering if it was something I could do on say internal brake routing type stuff where it's not structural but needs to look good. Of course, that's stainless tubing so it would have to bond to that and the chromoly to be worth doing.

When you do this, if flux involved with Silicon Bronze?
 

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SiBronze is fine for SOME structural stuff (makes a hell of a lap weld) but you're correct that the general consensus is not to use it for large fillet butt joints (which is generally considered the worst joint to use for brazing in all other industries). Still, you should be able to tig braze w/ regular gas brass rod too. Just about any rod gas can use, so can tig (and often visa-versa). One is chemical heat and the other electric. The bigger difference is that gas readily heats a large enough area to get a large fillet to wet out. TIG is usually too directional for that - it'll melt a small spot long before it can get surrounding area up to braze only temp.
 

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Discussion Starter · #6 ·
smdubovsky said:
SiBronze is fine for SOME structural stuff (makes a hell of a lap weld) but you're correct that the general consensus is not to use it for large fillet butt joints (which is generally considered the worst joint to use for brazing in all other industries). Still, you should be able to tig braze w/ regular gas brass rod too. Just about any rod gas can use, so can tig (and often visa-versa). One is chemical heat and the other electric. The bigger difference is that gas readily heats a large enough area to get a large fillet to wet out. TIG is usually too directional for that - it'll melt a small spot long before it can get surrounding area up to braze only temp.
Cool, so this sounds like the answer is that I need to try it on some test stuff. I'd really like to be able to use it as like a metal bondo as I mentioned above on the internal cable guides in the future perhaps.

Or it could come in handy for filling in the edges around the the seat sleeve, so metal bondo again. I suppose done right, I'd never need that, but I'm learning and it would be a nice tool to have in the bag of tricks. That's one thing I've learned so far with the WWTP is that you can't have too many tools in that bag.

I suppose I'm still curious about flux too.
 

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I've haven't used flux for SiBronze. Regular tig rules apply - everything must be CLEAN. Should be able to do a brake bridge ok. Trick is keeping the arc moving and/or a go for a soft fat arc. I've tried AC in the past, flat tip electrodes, etc to get a wide one:) Pointy tungstens are bad.

Give regular brass a try on some scrap. Got nothing to loose. I'll try some gas brazing rod I have next time Im tigging too. I've simply used the SiBronze since it was given to me:)
 

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jay_ntwr said:
metal bondo
You need to teach yourself to use body lead:) I've used eastwoods setup on a sunroof, rain gutters, fenders, etc on my old 911. Its the way all the factory seams were smoothed out for decades. I still used small dabs of bondo here and there though - lead still isn't THAT easy:)
 

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Discussion Starter · #9 ·
As you can imagine, I have plenty of not pointy electrodes ;) Most are getting too short to re-sharpen too. I'm going to need to order a new box for #2.

Cool, I'll monkey with it. I actually did consider the lead as I've been around paint and body enough to know that there was a time before plastic body filler but couldn't bring myself to add lead to a bicycle for any reason. That just seems wrong.

Thanks for the tips and I'll experiment a bit with it next time I'm out at the weld shop (on scrap stuff). Thank goodness it won't be for a while though. I'm sick of driving 150 miles round trip to weld on #1.
 

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SiBr is great. Makes adding fiddly bits easy. Good for small braze ons and such, no structural sections. There is a LOT of info available online. Look up "EVERDUR" & "TIG BRAZING" in your favorite search engine. The basics? No flux! The argon IS the flux. DO NOT use gas welding rod, use SiBr only. Do not melt the parent material! Set your TIG at a super low amperage to put heat into the material, the SiBr has a melting temp much lower than steel. (Hope it's cool to post some links) Some good info here: http://tinyurl.com/yfo5xg9 and here: http://tinyurl.com/yhw3ya6

RE: the CURTIS frame. It is brazed (sometimes the Brits call that style 'gas welded') using an inline gas fluxer. NOT TIG brazed. Very common in Aircraft and motorcycle chassis manufacture.
 

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Discussion Starter · #17 ·
ROSKO said:
SiBr is great. Makes adding fiddly bits easy. Good for small braze ons and such, no structural sections. There is a LOT of info available online. Look up "EVERDUR" & "TIG BRAZING" in your favorite search engine. The basics? No flux! The argon IS the flux. DO NOT use gas welding rod, use SiBr only. Do not melt the parent material! Set your TIG at a super low amperage to put heat into the material, the SiBr has a melting temp much lower than steel. (Hope it's cool to post some links) Some good info here: http://tinyurl.com/yfo5xg9 and here: http://tinyurl.com/yhw3ya6

RE: the CURTIS frame. It is brazed (sometimes the Brits call that style 'gas welded') using an inline gas fluxer. NOT TIG brazed. Very common in Aircraft and motorcycle chassis manufacture.
Thanks for all the links. That does help a lot actually.
 

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MIG brazing

On a similar note has anyone tried MIG brazing?

http://www.mig-welding.co.uk/brazing.htm

The joint looks solid but would the heat still be too much?

I'm looking at it for a tandem project a'la Sheldon Brown style from two MTB frames, cut apart and some new tubes inserted. I'd love to use oxy acetylene but I can't justify the massive rental charges for bottles that BOC charge for one small project but I have access to MIG equipment. So with the cheap addition of some appropriate wire could I have a broadly satisfactory set up for my requirements?
 

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Whatever you call it, the Curtis bikes are brazed... two bottles of gas mixed, flux (inline) and hand applied rod. The typical way to fillet braze. They used to have quite a few shop photos on their site.


-Schmitty-
 

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I've Tig bronze brazed before - just fooling around, But I found it very tricky as the HAZ becomes very very hot locally compared to gas brazing (as one would expect) and almost immediately the bronze spatters. What I found I had to do was heat up the area I wanted to lay filler into and then kill the arc, then fill in with bronze. I never tried the SiBr, and that sounds like it is a much better bet for tig brazing.

As far as flux coated rod - I peeled it off and just set the post purge fairly high to keep shielding gas on the area after I lifted the arc.
 
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