Brutally short 25mm steel ball crossbow

Discussion in 'Show off your homemades!' started by JoergS, Oct 17, 2013.

  1. JoergS

    JoergS Administrator

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    I recently came to the conclusion that draw length and draw strength are really in a 1:1 ratio regarding projectile speed. In other words, given the same taperung ratio, 18 kg drawn to 80 cm delivers the same speed as 9 kg at 160 cm.

    In order to build compact, effective crossbows, I am experimenting with super high draw weights. This new model - basically the same setup I have done in the past - is chambered for 25mm steel balls and should easily hold 250 lb draw force.

    I have now attached four full TGB strips per side, so it is at 157 lb. You cock the bands one at a time, much like you do on a powerful spear gun.

    This requires total strength and precision. It is made from top quality 18mm plywood and is 60mm (more than two inches) wide. Total length is about 70 cm for a 60 cm draw.

    Haven't tested the speed, but will do so on the weekend.

    The pics also contain an experimental Rambone in clear plastics, from the mould that apparently was just finished. I understand Helmut, owner of the business and the tool, wants to sell it in a few different colors but maybe also in a transparent version.

    It has so called vaccuoles (little voids) in the thickest part, from the shrinking plastic material during the cool down. Looks interesting, but is potentially weakening the frame. However, I tested it in the vise and at 70 kg (154lb), I gave up as my workbench started to groan quite a bit.

    I am excited that the Rambone will soon hit the market! I love that design, probably the best one I ever came up with.

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  2. xXdoomXx

    xXdoomXx Junior threadjacker ag. J

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    Cool design I have to get around making one can you suggest and easy and compact arrow or small bearing shooter?

    J
     

  3. onnod

    onnod Im from Holland, isnt that weird?

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    that's a beast, brutal!!
     
  4. BeMahoney

    BeMahoney Builder of things

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    Interesting, as always!

    Very interesting rambone and crossbow.

    But at one point i disagree!- The most loveable design of a
    slingshot is your outstanding MOORHAMMER.- it was the one
    that really bugged me.

    And I believe that rambone maybe could be slightly modified, be a
    little higher to function through-the-fork.

    But: who´s talking?- It´s just my thoughts.

    Respect!,

    Be
     
  5. artons

    artons New Member

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    can't wait to see the video!
    i'm quite sure that it will be one of the most powerful compact slingshot crossbow ever seen :D
     
  6. FIAAO

    FIAAO Failureisalwaysanoption

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    Cool! And very interesting...
     
  7. LW

    LW New Member

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    Yes, that’s what I like! And I like the Idea of making it smaller and handier but still very strong.

    Long time ago, I wanted to make a similar concept for a steel ball crossbow. I had already started, there are some nice drawings.
    And my concept for stretching the very strong bands was a kind of crossbow span aid.
    The very nice Idea is, that it is totally integrated inside of the body of the slingbow and you can not see it.
    So if you pull the span aid, you have double the power available, you otherwise could draw.
    Maybe you are interested in the system or the pics, I can send them to you, or if you want, I can post them here?


    I like to see the Power of this 25mm steel ball destroyer in action and in Video. :)
     
  8. JoergS

    JoergS Administrator

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    Why not posting it here? Seems like he right place :)
     
  9. Grumpyoldgit

    Grumpyoldgit Junior Member

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    May I respectfully suggest a cocking rope

    [ame]http://www.youtube.com/watch?v=MNi3qStrGTs[/ame]

    I use one on my crossbow (excalibur exomax),
    mainly to ensure the string is drawn equally,
    but it does make cocking a 225 lb easier than
    say a 130 lb cocked by hand.

    The 157 lb draw of the steel ball crossbow
    would feel like say 80lb.

    I just know JoergS will try doubling the bands
    if this works - 314 lb slingbow anyone! :D
     
  10. LW

    LW New Member

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  11. JoergS

    JoergS Administrator

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    I have two crossbows that require a cocking rope, and I hate them. I don't like a weapon that is useless once you loose a little thingy needed for loading it.
     
  12. LW

    LW New Member

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    That’s totally my opinion, I also have a crossbow (Horton) that I can cock without device (about 50 shots). If I shoot more, I use a cocking rope. (or I should have some training… :eek:)

    I do not know if you've seen the link, the advantage of the system is that the cocking mechanism is integrated in the body and you cannot lose it.
     
  13. Antraxx

    Antraxx #7

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    250lb? wow!
    Where do you think is the Limit for your wooden trigger design?
     
  14. JoergS

    JoergS Administrator

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    I don't really see a limit. It all comes down to the design and the thickness. This trigger/sear is 25mm wide, quite a bit of wood!
     
  15. Courier

    Courier Senior Member

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    This is a very interesting thread!
    Such a powerful x-bow would be ideal to shoot two zombies with one arrow. :)

    Just a thought... won't the force be so high that the arrow will be stuck in the target?
     
  16. CEZ

    CEZ New Member

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    Nice and simple design, can't wait for the results. Do you maybe have a drawing of the trigger?