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  1. #1
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    Default QUESTION: TIG Welding Gas Tanks and Other Bike Sheetmetal.

    Would you do a major repair on a gas tank with silicon bronze?

    Ever use it?

    Thoughts or advice?


  2. #2

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    The repairs i have done with silicone bronze tig brazing were on hairline fracture leaks. Sealed well. I would not hesitate to use it for more serious repairs on gas tanks. If im not mistaken, knuckle and pan hardtails are brazed together.

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    2016 Thread: TIG Brazing gas tank with silicone bronze

    http://www.chopcult.com/forum/showthread.php?t=48520

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    I just modified a fuel tank using silicone bronze. I relocated the petcock outlet/bung,
    & blocked off two redundant outlet/bungs.
    Afterwards, I filled the bath tub with water & used a shop vac with the hose plugged
    into the exhaust outlet to blow air into the gas tank partially submerged in water to
    look for air bubbles.
    the air will find it's way through tiny pin holes.
    Add more filler until there are no more bubbles.

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    Thanks all..

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    MIG brazing wire also makes nice filler for torch brazing as it's thinner than common brazing rods. If you want to make thin MIG brazing rod thicker ya can fold a long section in half, clamp one end in a vise then twist it with a drill.

    Brazing is rugged and shock-resistant. I used to braze steel rule fabric cutting dies (big cookie cutters used under high pressure) and the parent metal often snapped before the braze.

  7. #7

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    I've no experience building motorcycles but it seems that building custom bikes (or cars) is rather more art than science. Thus the hard part is likely to be building a following of those who admire your work. Learn to weld, learn to work sheetmetal, then I suspect a wise person would apprentice himself to an experienced builder to learn the finer points and also to build a body of work (keep pictures) to be shown to prospective customers in the event that one later decides to become independant.

    I don't think process is nearly as important as skill. Learn to weld, then pick the process you like and buy that equipment. O/A will add some time to a project, It's slower and thus it puts more heat into the metal that in turn results in more warping that may need to be worked out. Still it was the process of choice for body men until it was pushed out by mig. If you make three dimensional curves in sheet metal you will probably need the torch anyway to anneal the metal from time to time. If you want me to commit to a mig for you I would guess that you should go a step above the $300 mig to one of the 220 volt models. They are more capable and don't cost a whole lot more.

    Even 60 years ago these tube frame planes that I mentioned in another post were being welded together by women (the men were off in the war). I support the right of anybody to do any job they can (my daughter is a fireman) still I wasn't particularly put off by your statement.

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    A very skilled guy who does Brazing and metal fab for a day job is building a tasty Norton, 3 pages of discussion and pix, But hands down, he made some nice stuff.
    See: https://www.accessnorton.com/NortonC...-parted.34559/

    " The two are interchangeable. Fillet brazing is SIF bronze welding. You'll try and say otherwise, I'm sure.

    There are those that will tell you you're wrong for calling GTAW welding "TIG welding", but nobody really likes those people."

    (Yes ............,, but ordinary brazing is at lower temperatures to SIF SIF bronze welded parts.
    Brazing is NOT recommended for stressed parts like the frame joints, don't ask me how I know.)
    --------------------------------------------
    Well, I can't say how you control your heat, so your work is your work. There is no such thing as "ordinary brazing", but perhaps you mean "sweat brazing". You may have used an incorrect application of an alloy or technique if you experienced a failure. A correct alloy or technique will generally be stronger than the tube used.

    "Brazing" can be used to describe, fillet brazing, hearth brazing, and sweat brazing, amongst others.

    There are several alloys of brass (used colloquially) or bronze, maybe four or five silver brazing alloys, nickle silver alloy, amongst others. That's before we start counting name-brand proprietary alloys.

    I use the same brass or bronze alloys for both fillet brazing and sweat brazing. The strength of the joint is in overlap or fillet size, before we start in on an HAZ variable.

  9. #9

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    Tanks and such should be tig welded with steel.
    Then the item isnt contaminated and the next guy isnt trying to weld to any thing else.
    Yes early hardtail frames were 'sweat brazed' but that practice did not last for long.
    No need to complicate things any more than necessary.

  10. #10
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    Quote Originally Posted by SteveJ View Post
    Tanks and such should be tig welded with steel.
    Then the item isnt contaminated and the next guy isnt trying to weld to any thing else.
    Yes early hardtail frames were 'sweat brazed' but that practice did not last for long.
    No need to complicate things any more than necessary.
    Correct for the most part. I worked in Aerospace manufacturing for quite a while, Stainless and Ti mostly. Well known customers. While there I learned a ton about TIG welding and while I am generally considered a Idiot, I am proud to say I worked with some of the most skilled TIG guys in the USA. Amazing what some of those guys could do. As well, I had a thriving side hustle repairing old car and motorcycle parts using these guys. At one point I made more money on my side hustle than my hourly pay. Plus I paid the welders better. Theres a lot of science and tech involved in TIG, and my go to method of repair, But, for some applications Brazing is a option.

    As to confusing people later on,, if you clean the weld repair surface and see shiny gold stuff, pretty good clue what you are dealing with. That being said, I have seen some really BAD welds where someone didnt know what they were doing and tried to arc weld (Stick weld with Farmer rod) with Brass contaminants.

    Stock British bikes prior to 1971 are almost ALL hearth brazed. The steering neck, side stand lug, swing arm block, etc etc are all castings, and they are sweat & hearth brazed to the mild steel tubing of the frames. Theres videos of the factory doing these on Youtube if you care too look. Now, never fails some Knuckle dragging mouth breather will try to rake a frame without understanding the castings and steel tubing situation, and muck it all up. Even some really BAD advice in vintage chopper guides about slicing a V into a Neck casting and raking the neck and then stick welding in a chunk of steel. DONT DO THAT!
    I have few moron examples down in the shop we cut off I saved as teaching aids. Worse, generally covered in Bondo after they are done. I have another frame waiting on surgery that still needs surgery. (Cut off the badly executed rake job and do a proper neck install).

    *I will admit I screwed up once, (It happens, my wife reminds me all the time), But I had someone contact me about repairing their side stand lug on a BSA. Common problem, they break,. Especially if a Harley person jumps up and down on the kicker while on the side stand.. So they asked me to weld the side stand lug on, (Rabers used to sell a repair kit with steel machined to weld on.) So, on that model I didnt realize at first the side stand on the bikes were originally castings brazed on. It soon became obvious,, stuff bubbling out. I stopped, cleaned up the mess and took them to a local guy expert at castings and steel brazing. I knew the rest of the bike was castings, but my bad on that one.

    Brazing has its place, so does TIG steel, stainless and other rods. But they dont mix. The link to that Norton? Thats true old world craftsmanship by a master at his trade. True respect for his skills.

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    Why would a harley handlebar be listed as "1982 and up"

    ?

  12. #12

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    Quote Originally Posted by confab View Post
    Why would a harley handlebar be listed as "1982 and up"

    ?
    handlebar switches changed

  13. #13
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    The bar in question is a 1", dimpled bar. It would still work, right?

    I mean, that's what it had on it when I bought it?

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    Thought Doug would've brought it up, but prior to TIG, oxy-acetylene was primarily used to weld chromoly (not braze, weld) tubing in aircraft components. It is superior for welding sheet and castings ferrous and non-ferrous. TIG (especially MIG) pulls too much parent metal and raises the weld--so when its ground you're left with a thin joint. Gas allows the weld to be planished w/ a dolly and hammer. Check youtube there's all kinds of info on the process. Also no need to heat in the garage, a big bonus on my end. I was well on my way to buying an entire setup for welding sheet metal, but when I got to the welding supply they had a screaming deal on a mig unit. So I'm stuck with that and I'm not crazy about it.

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