Howdy! from NYC

Discussion in 'Welcome & Introductions' started by coyote-1, Oct 28, 2013.

  1. coyote-1

    coyote-1 Member

    274
    4
    18
    Hi everyone! I love creative weaponry. Been looking at the crazy Jeorg vids for a couple months, and finally when I saw the folding sling xbow decided I had to join the fun.

    I'm building a variation on that thing. (It's really a slingshot rifle by now, isn't it??) I'm using oak instead of plywood, and deploying items from home improvement megastores in the build. A Tornado 20 pound u-hook looks like it was designed for slingshots; the frame of a caster will function as a sear, a hinge stop will work as a trigger, etc.

    A couple of questions. First, has anyone measured projectile speed on a chrony? And second, what are the limits of rubber stretch? I want to use .58 lead, 280 grains, and want to reach "muzzle velocity" of 90 to 100 meters per second if possible. So the more I can stretch it the better, or so I imagine.

    Finally, a thing I learned using that ammo: a pair of opposing perpendicular splits with a razor knife make the hit even better. It deforms more readily on impact, thus transferring even more of its energy. And the sharp edges created by the razor knife help it dig into the target.
     
  2. Lacumo

    Lacumo Member

    400
    3
    18
    Welcome to SSC!
     

  3. Moin moin,

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

    [ame]http://www.youtube.com/watch?v=eRzTCKMg-lY&feature=c4-overview&list=UUxwJvKoro13H3GwmNfuI2Ag[/ame]
     
  4. JohnKrakatoa

    JohnKrakatoa Loudest boom on Earth

    1,287
    0
    36
    Hi Coyote ! I am looking forward for seeing all the parts from the stores incorporated into the sling gun!

    Nice vids Thorsten. Why did he use blue and not gold? Also holy ****. That much tapered bands last only 70 shots according to his video description. Wow
     
    Last edited: Oct 29, 2013
  5. JoergS

    JoergS Administrator

    5,803
    106
    63
    If you want to achieve 90 m/s, a slingshot rifle isn't the right weapon. You can only shoot that fast if you use a normal slingshot, draw it to full butterfly, and release with NO break at all.

    With the .58 lead ball, you won't get to 90 m/s though. The bands would have to be so strong that even a tough, trained athelete can't handle them.

    If you want high energy and momentum, choose heavier ammo. 576 grains is much better. With really strong bands, you'll be able to shoot them at 70 m/s or so. Think .75 lead (musket balls). Same energy as a .58 lead ball at 100 m/s, but 47% more momentum.
     
  6. coyote-1

    coyote-1 Member

    274
    4
    18
    Will start posting pics over the next couple days as I go, and as each idea succeeds or fails. And as I figure out how to get the pics to where they need to be lol

    But I have two components/concepts done:

    - The Tornado u-hook is at the end of the 'barrel'. Filed the wood to make it fit, and attached with screws. Might eventually reinforce with a "hold down" bolt. We'll see how it goes.

    - The 'sear' has been separated from the caster. A connector has been fashioned from a nylon quad electric box, and a slot put in it to attach to the trigger. The length of the connector is about four inches. This will allow a sorta 'bullpup' configuration, where the trigger is not directly under the sear.

    I'm going to use the roller release idea Jeorg used on a couple of his xbow slingshots. This will allow various sized ammo. In order to facilitate the fold-cocking mechanism, the roller release and sear will be mounted on a hinge. As it comes down during cocking, the sear will slide right over, and on to, the connector.

    That's it so far. Form will follow function; the device will essentially fashion itself to make those things work.
     
  7. Slagskimmer Mike

    Slagskimmer Mike thinks TBG smells better than roses

    985
    1
    18
    Welcome to the asylum where the lunatics rule, Coyote!

    I love everything about these ideas you are plotting, and I can appreciate your organic design method.

    The idea with the "split shot" ammo sounds great--gets my mind wandering in fun innovative circles.:D

    Please take lots of photos as you go, even quick phone pics are great to see and get ideas from.
    I'm excited to hear more about this gun and its development.
     
  8. coyote-1

    coyote-1 Member

    274
    4
    18
    Some mock-ups of the mechanism:

    [​IMG]

    [​IMG]
     
  9. coyote-1

    coyote-1 Member

    274
    4
    18
    The prongs, at the end of the 'barrel':

    [​IMG]

    Obviously I still have to make an auto-lock for when the barrel unfolds, and then I have to actually mount the various components. For the barrel hinge/pivot, I am considering a slot - and then let the tension of the bands pull the barrel back into a second locking pin. Would be very clean in appearance, while keeping all the tension in-line.

    I'm trying to use all "antique brass" finished fittings. So for my trigger guard I'll probably go get an antique brass drawer handle or something. But that's at least a week away from getting done.
     
    Last edited: Nov 1, 2013
  10. Will

    Will Thread Hijacker

    3,375
    2
    0
    Welcome! You have stumbled upon a great place that is full of great folks! Looks like you are doing a fine job so far on that sling rifle, looking forward to seeing it completed and in action!
    I hope you enjoy your time here as much as I do!
     
  11. coyote-1

    coyote-1 Member

    274
    4
    18
    Yet another visual mockup, the 'receiver' as it might look when finished:


    [​IMG]

    Note the hinge. I will try to create a mockup of it with the hinge open when time permits.
     
  12. coyote-1

    coyote-1 Member

    274
    4
    18
    OK, visual mockup of 'open' receiver (receiver would follow barrel as it closes)

    [​IMG]
     
  13. coyote-1

    coyote-1 Member

    274
    4
    18
    Thanks for the welcome everyone!
    Some lessons learned already:

    - I'm using furniture screws. My barrel pivot joint, while it works as expected, is slightly loose when locked open. I will rebuild it. The key is that the thread on the furniture screws is wider than the smooth parts. So the lock point will be drilled with a smaller bit.

    - Fortunately, the casters come in pairs. My alignment of the sear pivot was off on the first sear. Second one is correct. Using a simple finish nail for the pivot.

    I'm going to store ammo in the handle. It will hold perhaps six .58 lead balls or so, or a similar quantity of steel balls or marble. Used a drill to start it, will finish using a router.
     
  14. FIAAO

    FIAAO Failureisalwaysanoption

    3,648
    19
    38
    Welcome to the forum Coyote! The build looks very nice so far, nice work.
     
  15. coyote-1

    coyote-1 Member

    274
    4
    18
    This is turning into something of a build blog.

    After testing, the sear concept I've shown is workable but far from ideal. A simpler mechanism will work better. To make it work, the trigger will have to push, rather than pull, the connector.
     
  16. tokSick

    tokSick Senior Member

    3,951
    1
    0
    Hello and welcome. Nice project and i can' t wait to see it finished. Good luck with it.
     
  17. Ghosth

    Ghosth Over the hill but still swinging!

    975
    1
    18
    Hang with it, looks like a great start!

    Completed you should be able to drive tacks with that.
     
  18. coyote-1

    coyote-1 Member

    274
    4
    18
    Ammo dispenser, rough concept. Will be cut from nylon cutting board. Need to correctly locate the spring to force it back after dispensing.

    [​IMG]
     
  19. coyote-1

    coyote-1 Member

    274
    4
    18
    So I messed up the pivoting 'arms' that hold the roller release pins. Got a perfect furniture handle, halved it, drilled the pivot points.... the got carried away with myself, and used too big a bit to drill the posts for the rollers.

    Learned my lesson. Got the replacement, will take it slower next time.
     
  20. coyote-1

    coyote-1 Member

    274
    4
    18
    Was able to make new pivot arms from the remnants of the first ones. Tried a plastic base, but it flexed too much; there is no substitute for wood so I eventually scrapped the plastic in favor of oak. The hinge forms the top plate now.

    Went back to the original sear concept. It is workable. Needs a lighter spring than what I tried today, and the plastic connector might need a metal replacement.

    After that I'll have to wait til 2014 to finish it. The rubber will be arriving at Thanksgiving, but I'm going away for a few weeks and then there are the holidays...