3D printed in-frame plastic gas tanks

Discussion in 'Motorized Bicycle Welding, Fabrication and Paintin' started by KCvale, Nov 24, 2014.

  1. Ludwig II

    Ludwig II Well-Known Member

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    Have you thought about talking to a custom bike exhaust supplier and seeing what services they can offer for small production runs of what will be about the size of a silencer/muffler?

    They're used to working metal in curved shapes. Just a thought.
     
  2. FFV8

    FFV8 New Member

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    I have done rotational molding. It works, but the surface finish is usually "underhood automotive grade" - somewhat rough, with some grinding work on the outside.

    Then there is the issue of the cap, and how to attach it.

    To see a well designed plastic tank & cap, look at the tank on a Buell Blast

    Why not just use a tank from Ghetto Bike James?
    https://www.facebook.com/GhettoBikes

    He makes a nice metal tank.
     
  3. Ludwig II

    Ludwig II Well-Known Member

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    I think the important thing for KC is it's his design, his show, his gamble.
     
  4. KCvale

    KCvale Active Member

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    It is certainly worth looking into getting my design fabricated, but the bottom line is I just want reasonably priced gas tanks.

    This is the bike with the seat and bars adjusted to ideal for ~6" rider and ready for any non-manual clutch engine with really nice independent front and rear caliper brakes that deserves better than a P-nut tank.

    [​IMG]

    [​IMG]

    The problem with my design is the complex geometry, trying to get a consistent 'bubble' look from a flat piece of metal is not easy by hand.

    Thanks for the tip on Ghetto bikes, looks like he already makes tanks like that for the 29" frame, or darn close anyway.

    [​IMG]

    Not to distract from the topic but man that bike has one scary looking front fork, those smashed tube pivot points break easy enough on their own, rust sure can't improve their performance.

    Anyway, my tank is wider, 7" to carry more fuel, I'll see if he can just throw a couple of bends in the sides like this so it doesn't look like a board tracker.

    [​IMG]

    That's unique enough for me, and with the right paint job for the bike it should look pretty good for a staple build ;-}
     
  5. FFV8

    FFV8 New Member

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    KC:

    James will make anything you want. He is a skilled guy,and can work with a simple pattern to make what you want.

    Additive machining is generally a rapid prototyping medium. Skipping a lot of steps to get a single prototype out is a hurry is worth big bucks to companies like Lockheed - and they pay for it.

    And that fork? well, yeah. I have seen worse, but that one is pretty bad. At lest the tank will stay together when the fork fails.
     
  6. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    A 6" rider? That must be one tiny bike ;-} laff

    Staple build = cookie cutter build ;-}

    Ditching the P-nut tank is a big step in making a build look somewhat custom.....you're headed in the right direction now ;-}

    Heard about the new 5-stroke that's out now?
     
  7. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    I think you're onto something here Ludwig........that sounds like a great idea.
     
  8. KCvale

    KCvale Active Member

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    So much for exploring 3D printed gas tanks.
    No funds left for exploring that further.

    This $150 Columbia 1937 board tracker was begging for a real tank so I made it into one.

    [​IMG]

    It's just decorative sheet metal held on with some screws through the sides.

    [​IMG]

    I used a couple of struts to widen and hold the sides in place, and made a couple of poster board templates for metal to go around the whole thing.

    [​IMG]

    [​IMG]

    [​IMG]

    I took it to the welding shop around the corner with a petcock I took from a kit tank and a new filler neck and cap, and of course the bike so they could fit right....
     
  9. Chainreaction

    Chainreaction New Member

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    There is a lot of hype about 3D printing being the next greatest thing but truth is that it likely won't be of much use beyond prototyping and very limited runs. Watch something being printed, it is not a fast process.
     
  10. KCvale

    KCvale Active Member

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    ...
    They cut and bent some pretty heavy gauge steel to form and tack welded the top plate inside of the frame walls

    [​IMG]

    and the bottom plate outside the side wall.

    [​IMG]

    It has 3 acorn nut mounting holes, and the petcock is from the new style tanks with the outside threads so you can orient the level and it has a reserve.

    [​IMG]

    I taped up all the seams and holes and mixed up a 2/3 batch of Caswell gas tank sealer, it's a 2 part epoxy, and saved the not mixed 1/3's for a second coat just in case.

    The consistency of the mixed jells is a lot like maple syrup.
    The warmer it is, the better it flows, and yesterday at 4PM everything was at 80F.

    It was such a gorgeous day I just sat outside in my boxers and just put the tank in different positions on the table just kinda using my 'minds eye' to see how the syrup was flowing around in there.

    Sorry for the weather rub there... not, I live here for this reason ;-}

    When I finally got to draining out the excess caswell mix and I literally got some 'first hand' experience with what this mix will grab and coat with something impervious to any chemical I have here.

    While it was draining through the petcock tube I could see it was hardening and the stream getting thinner so I shoved a Q-tip in the hole to unblock it and got some on my hand, then the chair, then the BBQ...

    I figured the rest could just cure and laid the tank on it's left side (filler holes up) and noticed some syrup was still coming out the petcock hole that just kept getting thinner to the point of spider web, and I touched that too.

    They should market this as real spider man string hehe, anyway just use extreme caution when using the stuff and don't even think of using petcock tube with internal threads, they won't be there when you are done, much like a couple of my finger tips skin.

    I'm going to let it cure open outside until Monday to test it, and hopefully get it all cleaned, painted and installed then.

    I am liking it so far.

    [​IMG]

    [​IMG]

    I have a cooler exhaust plan but it hasn't even been fired up yet but so far so good.
     
  11. bluegoatwoods

    bluegoatwoods New Member

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    "So far, so good" is exactly right. The tank looks like it was made for that bike.
     
  12. Chainreaction

    Chainreaction New Member

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    I would say the cheapest and easiest way to produce nice looking tanks is to blow mold the basic shape and make a cover to go over it. No leaks and easy to customize. For the bikes I am building I am making round tanks out of exhaust tubing, making some out of 5" diameter right now. $56 for a 10' stick of 5" tubing, filler neck and cap $11.
     
  13. KCvale

    KCvale Active Member

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    A blown black plastic tank that would fit in the cavity with mounting points and screw holes to attach the bikes side plates would we awesome!

    Not just made for it, made from it ;-}

    [​IMG]

    The tank sealer is cured but I found one tiny air leak on the top back by the acorn nut for the top mount, otherwise it's air tight.

    Neat stuff and I have some left.
    One drop on that pin hole should do it.
    Then it's just making it look pretty and install it.
     
  14. Scott.D.Lang

    Scott.D.Lang Member

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    looks great nicely done
     

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