Copper Tubing Fuel Tank

Discussion in 'Motorized Bicycle Welding, Fabrication and Paintin' started by DaveC, Apr 15, 2011.

  1. DaveC

    DaveC Member

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    I so much like the copper tanks I've seen I decided to make one after my stock tank developed a leak at the weld for the mounting screw. I have Permatex Epoxy Putty'd all the mounting bolts but as they are prone to fail I thought a new tank was in order.

    I went to the recycling yard and found a piece of 3" tubing that had no calcium deposits, looked like a cut-off piece that was not used. Just down the street from there is a plumbing supply and I went to buy two caps. When he told me it was $38 each I about had heart failure. Told him no, thankx. He said he understood. Said the previous week he sold 4 4" copper pipes 20 ft long for $1600...dang. I went back to the salvage yard because I had spotted a piece of 3" with a cap, a short length about 8" going into a 3" x3" X1" T fitting. The 1" fitting perfect for a gas cap. The open end was cut off with a Sawz-All leaving a 3/4" stub sticking out to solder a cap to. With this set-up I just needed 1 more cap. Off to eBay, found a buy-it-now for $25 delivered. Got some silver solder and flux for $10, too.

    I have to remove the short piece of pipe. Heating up a 3" copper pipe enough to melt the solder at the same time poses a problem of getting it all heated up enough to take it apart before the solder cools and solidifies. I went on the net and found copper melts at a very high heat, almost 2000F and the solder melts at about 500F, really giving a safety margin of almost 1500F degrees before the copper starts to melt. I'm going to use my BBQ starter chimney to heat the fittings so I can get them apart. Not quite sure how I'm going to hang on to the parts, I have large Channellock pliers but they aren't large enough...I'll think of somethingscratg
     
  2. Elmo

    Elmo New Member

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    If you have a torch and it won't get the pipe hot enough beg borrow or buy another torch and and use both at the same time. Your idea using the charcoal starter should work also. In the early days of bicycle building they used a charcoal fire to braze the frames. They would put the filler material in the joints and put it on the fire.
     
  3. bairdco

    bairdco a guy who makes cool bikes

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    i've been soldering up copper tanks for awhile now. a benzomatic propane torch is a good investment. under 20 bucks at Ace.
     
  4. DaveC

    DaveC Member

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    I think I've seen a few of your tanks. Nice stuff. The torch will have to wait until the first of the month when I get paid. I called my sister who works at a rental place and I'll be using a acetylene torch with a rose bud to solder it back together.

    Now, the flux says water cleanup. I'm guessing I'll have to wash the tank out to remove residual flux. How well does the heated flux come off? Would boiling water help? I just don't think the disolved flux would do the motor any good :p
     
  5. 2door

    2door Moderator
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    Heat usually isn't the issue when taking apart old, presoldered fittings. The copper joints will gaul together and adding heat above what it takes to melt the solder only makes the matter worse.
    Try this: Heat until the old solder is flowing then apply some solder flux to the joint while 'wiggling' and rotating it and pulling out with channel locks or vice grips.
    Keep the heat source on the joint but don't overheat it. Just keep the solder in a molten state. Good luck.
    Tom
     
  6. DaveC

    DaveC Member

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    Thanks for the advice. I'm going to give it a try tomorrow. I do have options if I can't get it apart. Only problem there is I need two 3" coupler sections for about $35-40 shipped :p If I can get it apart then I have all I need for a tank. I have $55 in copper into it so far, think that's about enough for a gas tank ;)
     
  7. 2door

    2door Moderator
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    Dave,
    I forgot to mention that on material 3" in diameter you'll want to keep that heat source (flame) moving constantly around the joint, side to side for even heating. 3" can be a challenge keeping the heat even all the way around it. Good luck.
    Tom
     
  8. fishguts

    fishguts New Member

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    And you don't want to super heat it either if you use that charcoal chimney thing. It seems to makes sense to think the more heat the better, but solder doesn't like to flow right or adhere correctly if things are too hot.
     
  9. DaveC

    DaveC Member

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    That's why I'm just going to use it to take the fitted assembly apart. I done all kinds of things in my life but I don't think I want to try soldering with using charcoal as heat :)
     
  10. frankiethedrill

    frankiethedrill New Member

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    This stuff is great...I made an internal tank and it worked great. My only mistake was that I did not coat the entire tank and sure enough there was a bad weld that now seeps gas...I plan on re-coating.


    Caswell Inc. - Epoxy Gas Tank Sealer
     
  11. silverbear

    silverbear The Boy Who Never Grew Up

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    I would use the propane tank as suggested. Don't use a gas which is too hot you'll wreck the copper. 2door's advice to wiggle it when the solder is molten will do the trick. Then when you have it apart and cooled you can use steel wool to clean it up where the solder was. Emory cloth is good for that, too.
    I also had considered the copper pipe for an in-frame tank a year ago and like you could not believe what it costs and revised plans in a hurry. Rest assured, yours will be one of the few if not only ones simply due to the cost of materials. Searching a salvage yard is a great idea. Good luck.
    SB
     
  12. DaveC

    DaveC Member

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    Thanks for all these tips, guys. It rained yesterday(nothing new there :p ) so I'll be giving it a shot here in a bit. My welding Vice Grips open large enough to grip the cap and Channel locks will hold the rest of the parts.

    Price of copper...I can see how that would stop a build. If I hadn't found most of what I needed at the scrap yard for $4 a pound I could not have justified the expence of new copper. The 3" x 3" x1" Tee fitting alone $55 on eBay. Its a casting and very heavy.

    The 1" fitting is where the fuel cap will go. I'm still gleaning baffle ideas from previous tank builds. bairdco has a nice one. What I want to do is add a vent tube coming off the top like a MX bike for style and practicality.

    I also have a Royal Enfield Sediment bowl filter coming from India. I liked that it has wire bails but was dismayed to see it's made from chrome-plated plastic :p I've been doing some casting of aluminum and think I might try casting some brass tops for these filters. Broken cymbals from school marching bands can be had for free. Once a cymbal is broken it's toast.

    Since April the 1st the weather has been cold and crappy, slows down the progress:-||
     
  13. DaveC

    DaveC Member

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    Well, heating it up didn't help. Just too much area to get hot enough at the same time to take it apart. I'll just have to wait until payday to order couplers :( I think I can get the 2 needed for about $25 shipped :p I'll be $100 into this before I'm done but at full local prices it would be worth $200 or so.

    All because the Chinese think they can weld a screw to thin sheet metal and not have it leak.
     
  14. silverbear

    silverbear The Boy Who Never Grew Up

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    What did you heat it with? If a Bernzomatic torch with propane tank isn't enough to get it loose, then use a Mapps tank with the same torch, as it burns much hotter. it really should come apart without any beating on it.
    SB
     
  15. DaveC

    DaveC Member

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    I used a BBQ charcoal starter chimney :) Problem is there about 12-14 square inches of copper a 1/4 inch thick to heat up enough to pull a 3" cap off a 3" tube. I'd need 3-4 torches like that to do it.

    It's ok though, although I don't really like the extra expense of the couplers it does add another feature to the tank. A steam punk look is what I'm after and I think the couplers will add to that effect.
     
  16. silverbear

    silverbear The Boy Who Never Grew Up

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    "Problem is there about 12-14 square inches of copper a 1/4 inch thick to heat up enough to pull a 3" cap off a 3" tube. I'd need 3-4 torches like that to do it."

    I don't think that's true. I've taken a lot of old copper pipe apart. It shouldn't take much more heat to make the old solder molten than it did to solder it up in the first place. Ask a plumber if he uses three or four propane torches to solder up a joint in 3" copper pipe. I don't think so. But do what you want.
    SB
     
  17. bairdco

    bairdco a guy who makes cool bikes

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    you can also surround the pipe near the joint with ordinary red bricks, then use your torch in a circle to heat the pipe and the bricks. the bricks act as a kiln and keep the heat in.
     
  18. Tinsmith

    Tinsmith Member

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    You should be able to unsolder the piece using one torch like SB says, and Bairdco makes a good point. I have used bricks successfuly to heat metal. If you could find some old firebricks from a woodstove they are best. Someone suggested fluxing the joints as you heat and I also agreed that it should help. For $15 bucks you can get a torch and have a go at it Like Bairdco says, just keep running the flame around the piece to get everything up to temp and it should come off. Good Luck, Dan
     
  19. timboellner

    timboellner Member

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    Chances are if you have used large channel locks and squeezed the cap when it was hot you may have gotten the cap out of round, ovalled out.
    It will be really hard to get off in that situation.
    Don't squeeze the cap and twist and pull. You need a way to evenly push the cap off.
    Find yourself a refrigeration, a/c guy with a acetylene turbo torch with a big #11 or bigger tip. If that doesn't get it hot enough nothing will.

    TiM
     
  20. 2door

    2door Moderator
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    Been there...did that :)
    Tim, this reminds me of a job that took up an entire Easter weekend. 2 1/2" glycol line under the floor of a bank's computer room. A bad solder joint that started leaking and an overtime call. Trying to heat the pipe and coupling with glycol still seeping through...oh, Lord, NO! Dry coolers on the roof, 5 stories up and isolation valves that wouldn't hold. Couldn't find a 2 1/2" slip coupling; had to file the stop out of a standard to get it on. "(piping nailed to the floor, couldn't move it) Can you relate? :(

    Tom
     

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