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Thread: Shrinking Brass tube

  1. #1

    Default Shrinking Brass tube

    Is it possible to shrink brass tube slightly?

    I was at the hobby store, and bought some #2 pushrods to make rudder shafts, but the closest brass tube ( or any kind of metal tube) was 1/8 inch, which is close, but not correct. It's important to keep the gaps small on the rudder log to keep water out.

    thx.
    Last edited by TomoHawk; 02-24-2007 at 08:14 PM.
    Sail honest.
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  2. #2
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    Put it in the freezer!
    A.

    He who dares sometimes wins.
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  3. #3

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    Quote Originally Posted by Angus View Post
    Put it in the freezer!
    And that will permanently shrink the tube to the size I want it to be?
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  4. #4
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    Quote Originally Posted by TomoHawk View Post
    Is it possible to shrink brass tibe? ...
    It's important to keep the gaps small on the rudder log to keep water out.
    Tomo,
    The trick is to keep the tube high enough so the top will be above the waterline. Then leakage becomes impossible even with a loose fit.

    Is this for your Footy?

    Bill

  5. #5

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    That's how I build them, but there's some merit to having the good fit to eliminate slop. A sloppy rudder makes the boat hard to steer straight, IMO.

    I was thinking of heating the tube with the steel rod inside, and rolling them between some boards or metal plates. I've seen people shrink sheet brass by hammering it together, so my method is a little like that.

    thx
    Sail honest.
    Rock music.

  6. #6
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    I use to put teflon tape (what plumbers us on threads) on my pintals for my full size boat. Just wrap it around untill you get the fit you want.

  7. #7

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    I was considering using some gold foil, but I think that would be difficult to get it into the shaft log without nicking or cutting it. I think Teflon tape would be about he same, and only 1 layer would be needed.

    thx
    Sail honest.
    Rock music.

  8. #8
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    Quote Originally Posted by TomoHawk View Post
    That's how I build them, but there's some merit to having the good fit to eliminate slop. A sloppy rudder makes the boat hard to steer straight, IMO.
    Oh, ok...I thought the question was about leakage....
    I doubt that a little bit of looseness will make any difference.

    Quote Originally Posted by TomoHawk View Post
    I was thinking of heating the tube with the steel rod inside, and rolling them between some boards or metal plates. I've seen people shrink sheet brass by hammering it together, so my method is a little like that.
    Well, all I can say is give it a try & let us know if it works. If you're really all that worried about it, perhaps you could wax the rod & fill up the void with epoxy. Or you could wrap the rod with aluminum foil & insert it in the tube. How about some thick grease? Maybe that would help with the leakage "problem" at the same time. Let's see a picture of the boat.

  9. #9

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    I know what to do...

    Using either hard or paste solder, I will coat the shaft with solder and then sand it to fit in the shaft. That will be both hard and permanent.
    Last edited by TomoHawk; 02-25-2007 at 10:04 AM.
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  10. #10
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    you could try roller peening the tube.
    put the smaller shaft inside, then with something solid, like metal pipe.
    put the assembly on a hard surface, and mush down while rolling.
    just a thought.
    i'm going to try it now with some alu tube.
    tell ya if it works in about 10 minutes.

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