Fuel tanks

Discussion in 'Motorized Bicycle General Discussion' started by Ludwig II, Jul 31, 2012.

  1. thegnu

    thegnu New Member

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    ok heres a technique I use a sheet of paper reacts much like steel if you try an bend it , it will show you were it wants to stretch an also where it needs shrunk , cut your proposed shape in paper first seal with tape an use air pressure to gently inflate it it will show you almost exactly what will happen when you try to use steel or aluminum , doing things this way will keep costs down so you dont have to scrap all the failed attempts an keep buying metal as well as you will learn what shape the metal will have to have to get your desiered shape. that being said , if I were to form a tank , I prefer to use slightly lighter gauge steel than say 16 gauge do a test run with air pressure as you can hook up an control the pressure from a distance that would be how ever long your air hose is , once you get a decent one that way move up to the hydroform . the key to this is slow an methodical but worth it in the end . I have tried it didnt like it much .
    personally I prefer to hand form on a english wheel then use different hot an cold techniques , as well as hammer an dolly to get the final result . ya just have more control over the metal my way .if anyone would like to see some pics I built the tanks on threads mock up kinda rough , build no.2 wifes beach trike , an , felt guilty been holding out on one build . all done with hand forming techniques.
    Gary
     
  2. CroMagnum

    CroMagnum Member

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    Like I said, a lot of people make a lot of junk in their backyards. It doesn't mean it's always a good idea.



    Did you happen to read the Wiki page that locell posted? I quote - "Hydroforming is a specialized type of die forming that uses a high pressure hydraulic fluid to press room temperature working material into a die."

    Hydroforming is using high pressure fluid to press metal into a mold. It's not "hook a hose to it and blow it up like a party balloon."



    Well, I've been racing and modifying 2-strokes since I got my first Yamaha 90 back in 1969. (My first bike was a 1966 Honda C50, but that was a 4-stroke so it doesn't count here.) In the heyday of motorcycle publication I used to prowl bike shows and even the editorial offices and talk to the editors. I personally met and spoke at length with Gordon Jennings on several occasions before he wrote "The Two-Stroke Tuner's Handbook." Since I lived in the same neighborhood as Rick Sieman, Pete Szilagyi gave me a giant CZ sticker as a prank to put on top of the GYDBT. If you read Dirt Bike Magazine in the early 70s then you know what that means. I've been welding up my own exhausts and frames since I got my first torch back in junior high.

    So I've been around the block a couple of times.

    I have heard of this party balloon method before, and maybe it's more popular in the UK and with American squids on go karts. But nobody I know really takes it seriously. And here's why:

    When you force metal into a die it tends to forge the metal. It actually forces the molecules in the steel together and makes it stronger. This is what Detroit does hydroforming body panels, and what Harley does to make their "museum quality" frames.

    The Party Balloon method here does the exact opposite - it stretches and weakens the metal making it prone to cracking and failure. Basically creating an accident waiting to happen. Now if this happens to your exhaust and it springs a leak or breaks, no big deal. Your bike is just louder and runs poorly until you can get home to replace it. But if your gas tank fails, you could be in trouble.

    Once again, blowing up some metal like a party balloon is not hydroforming. It's just cheesy backyard engineering. Good luck.
     
    #22 CroMagnum, Jul 31, 2012
    Last edited: Jul 31, 2012
  3. tooljunkie

    tooljunkie Member

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    one thing i have read by using hydroforming as an art form,using a porto-power hydraulic pump.with water.just drain it and replace the oil when done.
    now depending on the amount of pressure used,it can be safe to create desired shapes to be welded together to create a fuel tank.
    beating something to death with a hammer doesent stretch or weaken it?
    or how about welding it?
    grinding doesent make thin spots?
    in comparison to the supplied china girl fuel tanks,hand fabricated tanks cant be worse than that,unless you soldered soup cans together.hang on,i think that was done and better than a china tank.
    if it wasnt for cheesy backyard engineering,we would all be walking and killing our food with a stick.

    i was a backyard mechanic long before i was a licenced one.
     
    #23 tooljunkie, Jul 31, 2012
    Last edited: Jul 31, 2012
  4. thegnu

    thegnu New Member

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    Hey i still kill my food with a stick ! Lol
     
  5. Ludwig II

    Ludwig II Well-Known Member

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    You kill your food?

    I don't bother, I just eat mine with it struggling.
     
  6. 2door

    2door Moderator
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    I kill mine by putting it in the same room I do hydroforming in :)

    Tom
     
  7. Ludwig II

    Ludwig II Well-Known Member

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    Now that's cheating.
     

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