The CopKilla

Discussion in 'Conventional slingshots' started by CEZ, Oct 19, 2011.

  1. CEZ

    CEZ New Member

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    Hi All,<br>This is my first post, great to meet you guys. Joerg - I'm a big fan, awesome work you do!<br>What am I doing here with practically no experience in slingshot design? I got so hooked up watching Joergs The Slingshot Channel that I couldn't sleep, eat or work out till I realized my own slingshot concept!<br>Being a professional 3d Artist I naturally made it in 3ds max first before I get to bending, sawing, filing, polishing, finger-cutting and other real-life stuff related to making a slingshot. <br>Here are some different views, I hope it's self-explanatory.<br><img src="http://i45.servimg.com/u/f45/16/95/98/50/sling12.jpg" border="0" alt=""><br><br>Yes, I realize that it looks pretty ugly with the arm brace (it's legal here, no worries:) but just think how much thera band can fit in there! It's foldable too!<br>The material I plan on using is aluminum bent under a cheapo blow-torch for the frame and brace, 2 small rollers if I find some, a steel rod which will hold the rollers, any kind of wood I can find and of course Thera tube black (double layer)!!<br>I have a small hand and want this to be as compact as possible so I guess it would be about 10cm for the handle, 5cm for the fork, 15cm for the brace and if I'm not mistaken it could hold up to 30cm of thera tube per side with not much dead play.<br>So what do you think, will it work? <img src="http://illiweb.com/fa/i/smiles/icon_bounce.gif" alt="bounce" longdesc="27"><br><br>Cheers!
     
  2. Cylvre

    Cylvre New Member

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    You'll want to be very careful with forming the aluminum. Heating it to bend can change the crystalline structure and make the joints weak and/or brittle. I don't know your experience with working with aluminum, but it doesn't harden and heat-treat the way that steel does. It's a work hardened material and methods that are used to harden steels (for example, heating to high heat and then quenching, or cooling quickly) will make aluminum soft and/or crumbly. Definitely not an ideal state for a frame that will need to absorb a lot of stress and tension.<br><br>I do like your idea for extending the usable rubber in the design though. I'm interested in seeing what those more knowledgeable about slingshots have to say about it.
     

  3. Ryan Wigglesworth

    Ryan Wigglesworth Senior Member

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    Holy Hell I love that design! <img src="http://illiweb.com/fa/i/smiles/icon_twisted.gif" alt="Twisted Evil" longdesc="13">
     
  4. JoergS

    JoergS Administrator

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    Without rollers at the top, the rubber will jam. You won't be able to cleanly shoot this one. Also, the band direction is dangerous, it will tend to flip the ball downwards, it may go wild. <br><br>Also, you will have to shoot this one in fly butterfly. The bands are much too long for a normal draw. <br><br>Also, the fork is too wide, if you use rollers on top (which you would have to, as I said), the bands would "want" to slip off. <br><br>As cool as it looks, the design needs many improvements or else it will be a failure. <br><br>No offense, this is just from my extensive tests with such frames - I had many failures myself and know exactly how rubber "behaves" when shot over rollers.
     
  5. CEZ

    CEZ New Member

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    None taken, thanks heaps! There were rollers on the top in my first idea but I took'em off so it looks cooler :cyclops:<br><br><br>Will it help if I give the fork more of a Y shape and a narrower fork?<br><br><br>And what about the aluminum for the frame? It's 8mm thick, think I should be able to bend it without too much heat and that thickness would hold the shape but since I have a blowtorch anyway I can go for metal, steel, brass, maybe not titanium :rendeer: <br><br><br>I had another vision over the night by the way, it was about it was about turning the fork more to the front and making it even higher and longer, as well as handle and brace... The previous design was cute lol, but I want to make it BIGGER, BLACKER and MORE EVIL!!!<br><br><br>Thanks for the feedback anyway, I will definitely take it into account in the next vis I send over. <br><br><br>Cheers!
     
  6. JoergS

    JoergS Administrator

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    8mm aluminum is a bit on the thin side, but will work if the design is good. <br><br>8mm steel is a lot better, and can be welded much easier than aluminum. <br><br>Why don't you make a starship first, just forward extended and without rollers? Rollers are very tricky, and a forward extension works better than rollers because there is no friction. The only reason I have to use rollers is because a forward extension requires braces, so that would be illegal here.<br><br>A high fork is counter productive, it makes the frame weaker, not stronger. <br><br>Do you use Lightwave for your 3D rendering?
     
  7. CEZ

    CEZ New Member

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    Then steel it is! <br><br><br>Well starships are huge and I'm small:D Seriously, as I'm kind of a Ikea guy I want the best performance/power in the smallest possible package. I even thought up a way to collapse the fork and brace so it doesn't take much space, just remove the little bolts in there:)<br><br><br>I use 3ds max and vray, I work for a product design company so this was pretty easy for me in max, wonder how long it'll take in real life:) Here's a new render, will this work?<br><img src="http://i45.servimg.com/u/f45/16/95/98/50/sling210.jpg" border="0" alt=""><br><br><br>By the way, can a simple blowtorch like this(suppose to give 1300ºC) actually weld stuff like steel?<br><img src="http://www.ultimatehandyman.co.uk/blowtorch.jpg" border="0" alt="">
     
  8. JoergS

    JoergS Administrator

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    I don't think you can weld steel with a blow torch. I use a TIG welder.<br><br>Issues in your new design:<br><br>- Band length too long. YOu would have to have gorilla like armspan to use this kind of band length.<br><br>- Top rollers are outwards canted, which will cause the bands to climb over the inner rim of the rollers. Best is to keep them 100% parallel. <br><br>- Steel rods are bent before and after the rollers. This is physically impossible, you would have to bent the steel after the rollers are on. This would cause the rollers to jam. The rollers need to be detachable. <br><br>- Fork is too high, lots of unnecessary strain on the wrist brace<br><br>- Brace is too short to be effective
     
  9. Ryan Wigglesworth

    Ryan Wigglesworth Senior Member

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    Man, you came to the right place if you want to make that thing work! Joerg has got all the help you will ever need <img src="http://illiweb.com/fa/i/smiles/icon_biggrin.png" alt="Very Happy" longdesc="1"><br><br><br>The design looks amazing on paper, apparently not in practice though lol<br><br>I can't wait to see what else you come up with, considering the high quality of your drawings!<br><br>Good luck!! :alien:
     
  10. Tobias

    Tobias New Member

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    you found a good software to made this! looks like real! <br>this is your first slingshot? how long you shoot with Slingshots?<br>perhaps it is better first with a simple start.<br><br>Good luck!
     
  11. Yamroll

    Yamroll New Member

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    Most steel won't melt until after 1350 C or higher. It depends on the alloying elements and proportions.<br><br>Part of the problem with trying to torch weld is that while the steel may melt, the surrounding steel may be heated to a point that you'd have to be very careful about how you cool it. You may wind up with a weld, but with all the metal surrounding it grainy and brittle.<br><br><br><br>You may be able to get a good weld out of an oxy-acetylene set up with the right fillers, but I'd be careful to temper your pieces afterwards to keep risk of catastrophic stress failures to a minimum.<br><br>Better yet, TIG.
     
  12. CEZ

    CEZ New Member

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    Hi all, glad you like my images. <br>Here's another try at it, think it will shoot more or less straight without killing me in the process? <br><br><br><img src="http://i45.servimg.com/u/f45/16/95/98/50/sling310.jpg" border="0" alt=""><br><br><br><br>Joerg I took ur advice and shortened it, at the current proportions it holds about 25cm of thera band.<br><br>What do you think of the bolts in the rims that hold the rubber from falling off the rollers?<br>By the way, I have designed it so it that it doesn't need welding, just heat bending;)<br><br><br>This will be my first slingshot since school probably, I just like to design and build stuff, if it works then hooray!<br>I'm starting to like this look, just not sure if it's not posted in the wrong thread, should be the Krazy Kontraptions if you ask me:)<br>Anyways, what do you think of this one?<br><br><br>Cheers
     
  13. JoergS

    JoergS Administrator

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    The rollers should be larger in diameter, otherwise the action won't be very smooth. The bolts will hold the bands fine, but will also damage them sooner or later, an unavoidable problem of band guides in general.<br><br>When you pull out, the bands will still tend to climb up inwards, because the angle is that way in the early draw out phase. <br><br>This is now a lot better already, but can still be improved.
     
  14. CEZ

    CEZ New Member

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    That's awesome, thanks Joerg, I thought this bird will never fly to be honest;) How about I use a double black thera tube instead? I have ordered those too, just in case.
     
  15. ZDP-189

    ZDP-189 New Member

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    I like the first design with the low deflex forks.
     
  16. Cuthbert Allgood

    Cuthbert Allgood New Member

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    i think you should just make it. You will learn so much more when you shoot it and then you can rethink the next design based on what you learned.<br><br>
     
  17. Hrawk

    Hrawk Hedonistic Decedance

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    HI Hierdul and very nice render.<br><br>Nice to meet another Max user. Lately I have been modelling all low poly stuff for a VR engine.<br><br>Question, have you ever tried and / or using reactor to simulate animated slingshot bands ?
     
  18. CEZ

    CEZ New Member

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    Hi Guys, I'm not giving up on this but for the time I don't think I have enough skills and experience for it and first I'd want to make a bullpup:)<br><br><br>Nope, haven't tried reactor. It's an idea but that kind of simulations are way out of my league, I do vis stuff:)<br><br><br>Cheers
     
  19. Hrawk

    Hrawk Hedonistic Decedance

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    No worries man,<br><br>I have tried every possible option I can, and it still acts like cloth.<br><br>Guessing about now I should just give up, I don't think reactor has the necessary functionality to do what I want.<br><br>I hate keyframing <img src="http://illiweb.com/fa/i/smiles/icon_sad.gif" alt="Sad" longdesc="3">
     
  20. CEZ

    CEZ New Member

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    I think it's more fun to test it real life right now:)