Glued trunnions?

Discussion in 'Cannon' started by BCarp, Nov 21, 2014.

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  1. Nov 21, 2014 #1

    BCarp

    BCarp

    BCarp

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    Last edited by a moderator: Oct 27, 2018
  2. Nov 21, 2014 #2

    coloradoclyde

    coloradoclyde

    coloradoclyde

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    properly done I think it would be fine for the miniatures.
    A full scale gun would be a different story.
    your sheer strength would come from the socket.
     
  3. Nov 21, 2014 #3

    trent/OH

    trent/OH

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    At some point, somebody is going to put a projectile in the bore and fire it. Said person will then be educated on Newton's Third Law, followed immediately by Murphy's Law.
    If you want a signal gun, a Thunder Mug is the way to go.
     
  4. Nov 21, 2014 #4

    coloradoclyde

    coloradoclyde

    coloradoclyde

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    The question I have is; are they designed to fire a projectile? his videos look almost like blanks.
     
  5. Nov 21, 2014 #5

    Coot

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    The website description for each model states that they are "signal guns only" and "not intended to fire a projectile". I would take him at his word.
     
  6. Nov 21, 2014 #6

    talon

    talon

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    He states that for liability reasons.
     
  7. Nov 21, 2014 #7

    coloradoclyde

    coloradoclyde

    coloradoclyde

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    I have no personal experience with his cannons. But,
    If you’re scared about the JB Weld, Don’t be. I have fixed and fabricated many things using JB Weld ,and two part epoxies and urethanes. I have had virtually no failures. Those that did fail were the result of improper application and not product failure.
    JB WELD is used everywhere from the home garage to industrial applications.
     
  8. Nov 21, 2014 #8

    coloradoclyde

    coloradoclyde

    coloradoclyde

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    Here is some JB WELD stength data.



    Tensile strength: 3,960 psi or 27.3 MPa,

    Adhesion: 1,800 psi or 12 MPa,
    Flex strength: 7,320 psi or 50.5 MPa, and
    Tensile lap shear: 1,040 psi or 7.2 MPa


    It is most likely that the car you drive is held together by "glue"
     
  9. Nov 23, 2014 #9

    Zonie

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    Just so people will understand how those values work, notice they are in pounds per square inch.

    That means if the contact area or the size of the blob has a crossectional area of one square inch, those numbers are what you should expect.

    That all sounds wonderful until you start looking at the crossectional area of the joint your dealing with.

    Lets say it is one inch long and one half inch wide. It's crossectional area would be 1" X 1/2" = 1/2 square inch.
    With this amount of area it will only have 1/2 of the values given.

    If your dealing with regular guns and putting a front sight on, the typical blade might be 3/4" long and 1/16" wide. That would have a contact area of .75 X .062 = .047 square inches so the adhesion strength of the joint would be 1,800 X .047 = 83.7 pounds. Adhesion strength is the amount of force needed to pull something straight off.
    In many cases, something trying to knock it off from the side would be a more common condition.
    In that case, you would use the Tensile lap shear strength. The .047 square inches mentioned in a shear condition would be expected to fail if a force greater than .047 X 1,040 = 48.88 pounds was applied.
    :)
     
  10. Nov 23, 2014 #10

    54ball

    54ball

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    Would You?
     
  11. Nov 23, 2014 #11

    coloradoclyde

    coloradoclyde

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    Zonie,
    Did you take into acount the strength and added surface area of the socket?

    Also my CVA Old Ironsides replica appears to be made in such a fashion, but I cannot say for sure without attempting to dismantle.
     
  12. Nov 23, 2014 #12

    Poor Private

    Poor Private

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    I sure wouldn't use it on my cannon. A 1oz. charge out of a 1" barrel. But my main question is is this at a static(unmoving,no kick) pressure? Seems to me all that jerking back by a barrel thats supported, suspended and attached mainly by the trunions would be way to much for JB Weld, especially if it's anything larger than a desk top cannon.
    My small cannon weighs in at 45# and has 1" trunions that are welded in place, in sockets. I don't think I woudl have bought it if it hadn't been.
     
  13. Nov 23, 2014 #13

    coloradoclyde

    coloradoclyde

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    No! No! Not on a full or scaled down cannon. That is just asking for trouble. :slap:

    I am referring to miniatures only!
    Remember these trunnions are glued in not glued on.
    while glueing does add some shear strength the primary function is to keep them from coming out.
     
  14. Nov 24, 2014 #14

    Zonie

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    I was just mentioning how the strength numbers apply to an adhesive.

    If the trunnions are installed in a hole machined in the sides of the barrel and held in place by some glue, the metal holes and outside diameters of the metal trunnions take most of the load if the barrel is fired.

    If the trunnions are just glued to the outside of the barrel, the glue will be taking the shear load when the barrel is fired.
    _____________

    As for static pressure, that only exists before the powder lights. When the powder explodes, things are anything but static.

    When firing a 1 ounce powder charge with nothing else in the bore, the gun is basically firing that powder out of the muzzle. That is a 437.5 grain projectile equivalent.

    What most people forget is the weight of the powder is being expelled from the barrel and this powder weight creates recoil.
    .
    In this case, it is 7000 grains/pound divided by 16 to find out what the powder weight is. In other words, one ounce of powder weighs 437.5 grains.

    A 437.g grain projectile equivalent would compare with a firing a 278 grain .570 caliber lead roundball from a gun using 159 grains of powder. (278 + 159 = 437)

    The recoil will probably be different based on the weight of the cannon barrel but a one ounce powder charge will create enough recoil that it should be considered before touching it off. :)
     
  15. Nov 24, 2014 #15

    BCarp

    BCarp

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    Thanks, gents, fr the info and insight. I'm looking to mount a swivel gun in the bow of my period boat. It will be used mostly for firing blank charges at reenactment events. My concern re: the trunnions is that the entire force of any recoil will impinge directly upon them, as the gun will be mounted on a yoke set into a wooden stanchion. No rolling back in a carriage with wheels!
     
  16. Nov 24, 2014 #16

    coloradoclyde

    coloradoclyde

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    Mounting the gun on a yoke will increase the shear force exibited on the trunnions, best to consult the manufacturer.

    If that boat touches the water you could get ticketed or thrown in jail and have your gun and boat confiscated, especially if it is on a federal waterway. Best to check the laws first.
     
  17. Nov 25, 2014 #17

    BCarp

    BCarp

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    Oh, no, no, no! Swivel guns on period (re-created historic) boats are as common as oars. Check out this listing: http://www.privateermedia.com/Boats/boats.htm
     
    Last edited by a moderator: Oct 27, 2018
  18. Nov 30, 2014 #18

    kaintuck

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    I'll read about it in the newspapers one day......this is post 911, whole different set of people, everyday brings new challenges to law enforcement......I know how I would feel being called in on a report of a boat with amounted cannon on its deck....shooting! :shocked2:

    I sold my 2-14" field piece....she was fun, but I can see where trouble can be brewing these days..... :headslap:
    Marc n tomtom
     

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