Cannon Construction

Discussion in 'Weapons & Pneumatics' started by tgalx3, Sep 20, 2020.

  1. tgalx3

    tgalx3 Active Member

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    I am going to try my hand at building fast gun cannons. I found a couple of threads on big gun constructions.

    does anybody have a thread they can point me to for designs and construction? I have a solid understanding of how the old fashioned copper guns work but was interested in a new design but certainly not a requirement. I was intrigued by something with PVC or Styrene.

    The second question, if I have to build the older style copper gun, does anybody know where to get the more specialty parts for it. I.e the little “T” plunger in the bottom and the spring.
     

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    Last edited: Sep 20, 2020
  2. Anvil_x

    Anvil_x Well-Known Member

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    there are quite a few threads regarding the topic, "Anatomy of a Fastgun" is a good one. I think people generally use rivets and bore them out. @Bob could you touch on this if it's not already in a thread? if in a thread, could you share a link please? I thought I overheard you and Tyler talking about this stuff a few weeks back in Chanhassen.

    PVC is not a great material for the purpose. I use nylon tubing for my mag tubes and a modded compression fitting, with PTC end cap reducers. I'm gonna do a "stem-to-stern" with a fully disassembled cannon here in the next few weeks, so bear with me. it'll be the Idaho.

    this of course has a caveat that nylon tubing may not be fantastic in hot weather applications. my boats have not gone south of the 44th parallel, so I don't have to worry about monstrous internal temps messing with my materials. yet. I would defer to @Beaver for that, since he passed the technique to me, which originally came from @SteveT44

    there was a great thread here just the other day, in which a lot of good stuff was mentioned:
    https://rcwarshipcombat.com/threads/ircwcc-sms-baden.446418/page-11#post-534885
    @wdodge0912 was troubleshooting his Baden and a few folks swooped in to help.


    there are a ton of resources in the threads toward your ends. they may not be jumping out immediately and there has been a discussion on making some pinned curated threads to resolve the issue, but they are there. I would suggest reading and reading and reading some more. if anything, there are some great laughs in there.
     
  3. Kevin P.

    Kevin P. Well-Known Member

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    For the pistons, 3/16 x 5/8" Stainless steel flat head rivets. https://www.mcmaster.com/97386A247

    Can also cut down a screw with an unthreaded section - Use steel or stainless, brass will dent from BB's

    For springs, @Beaver has a nifty spring winding jig and might be willing to hook you up

    I would not recommend using PVC for any pressure-bearing application, the shattering failure mechanism makes it a safety hazard in my (and many others) opinion.

    Copper guns are still the standard.

    There are a few applications where plastic magazines make sense for weight savings - light cruisers, DD's, etc.

    Here are some pictures of the plastic magazines. Need to find or cannibalize the red collet piece.

    B0852FE3-F252-4ECA-949D-65C53B936862.jpeg
    Drill the end nut out enough to fit the collet. Get 1-2 o-rings with a 1/4"ish ID to make the seal
    A55EEB3B-1147-454F-A7EA-AB522EC4BC67.jpeg
    19CEFE8A-C431-4DE1-A703-0C0F3FD03654.jpeg
    Pictures of the collet
    80CE2F5E-8863-46C8-88AC-49D31E4DA5B8.jpeg
    89CF5022-D70B-40CF-AA1F-6E6AF27E236E.jpeg
     
    Last edited: Sep 21, 2020
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  4. Anvil_x

    Anvil_x Well-Known Member

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    Oh hey, the Collet!

    I just dug out the bag where I got mine. I use Shark Bite 1/4" OD Tee fittings. can be found at any hardware store.
     
  5. pacific

    pacific Member

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    As someone that used to build PVC air rifles when I was a wee lad and got chewed out by my surgeon neighbor, PVC doesn’t like to show up using most imaging technology. So when it fails and becomes shrapnel they will be trying to fish out invisible shards. Don’t pressurize PVC.
     
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