A most likely terrible idea, could use some tips.

Discussion in 'New project ideas' started by AttilaTheFun, Sep 17, 2013.

  1. AttilaTheFun

    AttilaTheFun New Member

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    Well hey there!

    Sooo I was sitting on a train getting home from a small vacation with my Girlfriend. I was kinda bored, just staring out of my head, and when I saw the armrest of the seat (its... umm "foldable"? you could move it up so its not in the way) a random idea just popped into my mind.

    I'm quite sure has been done already lots of times but I thought it could be a funny little toy soooo.

    [​IMG]

    Here's a picture showing the rough design (i started making it in blender but... i just got inpatient:D)that shows the bow not draw and drawn. The grey line of course is the string, the orange-ish is the rubber band. Could this work properly as a bow?

    I'm not sure about the dimensions yet but I'm really not the mathematics type, i'll just build it and play around with the bandset if the design seems eligible.

    Thank you very much guys!
    Attila
     
  2. Withak

    Withak aka Whitehawk!

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    Interesting design. Looks like something that would be right up Joerg's alley. Seems to me (with my limited experience) to be somewhat a variation on the idea of the compound bow. I'd like to see what you do with this. I'm afraid I can't really help with the design/engineering, but I can certainly offer some encouragement to do it!
     
    Last edited: Sep 17, 2013

  3. Ghosth

    Ghosth Over the hill but still swinging!

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    In theory, potentially yes it could work. But remember, every piece, every joint, you add costs you efficiency, becomes a potential spot for failure.

    Shorten the string, remove the 2 extra arms and it will for sure work.

    Keep it simple = keep it effective. Every point of added complexity becomes a point for potential failure. That being said it "looks" interesting, and original.

    I'm far from an expert, but the most effective designs I've seen so far all seemed to have simple forks but extended handles for long draws, and accuracy. Like what Jorge was shooting 9 inch nails out of.
    However I'm also not wanting to "rain" on your parade either.

    Best of luck!
     
  4. Jeremy

    Jeremy Senior member who totally rocks a pink Scout! Pink

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    It looks interesting and promising. I hope the project comes to fruition.
     
  5. Brazilviking

    Brazilviking Thread Hijacker

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    This is ingenious and has lots of potential! It's the same principle that makes that "raptor" bow works! Seems that you had a brainstorm, man!
    I've saved your picture, and probably in the future i shall take advantage from your great idea!!!!!
     
  6. AttilaTheFun

    AttilaTheFun New Member

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    Wow!

    Thanks everyone for the answers, the encouragement and constructive criticism :D

    etrain / Jeremy: If everything goes well I'll post pictures and a video in some weeks.

    Ghost: I know complexity=/= efficiency in this case, yet I think I'll keep the design. This is one of my weakspots, I love complex things, Rube Goldberg machines and things like that. Yet Thank you for your advice!

    BV: Brainstorm? Yeeeaah...well, it's not my first:D I'm still working on some basic design for a slingbow that has a barrel and you load it like a musket and it copies the musket's actual trigger mechanism (Simple mechanics instead of gunpowder of course) and a small a forearm mounted slingxbow that uses syringes for trigger mechanism (first in hand, second built in in the slingxbow, once first is pushed, second one pushes it's piston out releasing the lock mechanism) So I'm kinda overwhelmed sometimes with ideas and i don't really have the time to do them. Problem with my case is I live in a flat, I do not have the space, the materials and the neighbors wouldn't like the sound either:D I can only work on my projects when I'm at my Girlfriend's parent's place (gahh i need for find a shorter definition to that:D) and that like every second weekend (that's why i cant make this project like RIGHT NOW:D)

    I'd be honored if you used my idea to build something. I'd love to see the design made with some crazy medical braces (I don't know the term for it, I mean the stuff You used to make some of your slingshots :D).
    Especially since even if i make it, it won't be the strongest one. I'm a terrible cheapskate, (My payment isn't that bad in Hunagrian standards but it'd be laughable compared to others BUT theraband cost the same even here in Hungary (actually a bit more) compared to the US for example and no free shipping in Ebay to here) I tend to keep every dime I can as we are saving up for our own house. I only have TBB but Ill see if using a lot of that helps :D

    So thank you guys! If everything goes right 2 weeks and I'll have pics, vids and report on this matter :)
     
    Last edited: Sep 17, 2013
  7. Baller-Bub

    Baller-Bub New Member

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    Hey Attila
    As you draw it, it looks nice, but doesn´t make much sense.
    But if you attach the rubber half way to the levers, archimedes said you gain speed from power!
    be sure to take lightweight and stable levers, and make sure the hinges
    go sneak, then you MAY gain a plus of aproxx. 30-40% of the rubbers speed!
    Losses should be included in my estimation.
    Have fun, build, it show it!

    PS.: I have the same time/space issues... And if i only come up with it, i´ll do a compund slingy, but with Cams like
    a compound bow.
     
    Last edited: Sep 17, 2013
  8. dolomite

    dolomite Banned

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    it's called the Raptor, already been done. shoots arrows and 12mm steel, pricey though.
     
  9. BeMahoney

    BeMahoney Builder of things

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    started htis post three hours ago.. work..

    Hi everyone,

    I was "compounding" around, too.

    you might also have an opinion to this:

    https://www.theslingshotforum.com/f7/guenstiger-latex-nachschub-30936/index3.html

    the point is the use of leverages..

    concerning yours:
    as well as my suggestions, you will have more mass to
    accelerate (extra arms); extra speed is gained by that "flip"
    when the string straightens (but only if the ball is still in
    the pouch at that moment...)

    greetings,

    Be
     
  10. Brazilviking

    Brazilviking Thread Hijacker

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    Hey, Be! Stop hidding you nice funky stuff on that "scheleuder deustche" forum! I never check those posts..... Can't understand anything! Using a traslator program results in "I shot the corn on the cockatiel and the villagers ran away"
    That seems very scientific and well researched!
     
  11. BeMahoney

    BeMahoney Builder of things

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    begging pardon

    Hi B.V. you got me!:

    Guilty of having let myself go in my mothers
    tongue (although part had been translated.. )

    Dunno-Y, just happened :) and it´s not that well researched as it
    might seem, its just little sketches..

    That one big question is: how far will increased mass (of leverages)
    compensate the increasing speed of that string?

    Plus: I will have professional support by a firm building high-end,
    high-tech automotive parts (Maserati, Lambo, Porsche, Benz..)
    Because of that and because of those aluminum-barrels lounging around
    here, I cant avoid to approach that topic mentally..

    Greetings to Brazil,

    Be







     
  12. AttilaTheFun

    AttilaTheFun New Member

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    Ah well... Hey there!

    Sooo a bit of update about the sour news :D
    We're spending the weekend with my Girlfriend at her parent's place and i saw some wood i thougth could work as good material for this project with a weaker bandset.

    So I started to work, made some cardboard cuts of the design, drew it on the boards and cut them off. Since I had no rasp (well I bet I had about 10-20 rasps but my Girlfriend's Father keeps his tool shed so messy I looked for a rasp for more than an hour and gave up) I used an angle grinder then some sanding paper to work out the fines shapes of the wood. After that i made the connections between the base and the extra arms it worked quite well. I played around with the tube attachment for a while (Oooh guys I forgot to mention just a few days ago I found a crappy chinese slingshot lying on the ground while walking the dog XD the tubes are a bit crappy but I though it'd work well for this project) then came up with a method with hook screws that seemed nice and worked well. Just when I was trying if the attachment was strong enough ... crack... one of the extra arms broke... and I think my heart as well. The wood was clearly too weak to handle the mechanic stress for long. I took a deep breath, scavanged the screws, the metal bits I used for connection and other things that might be useful and calmly took the rest of the wood to the chopping block and murdered it with every bit of might I had :D

    Sooo part of me is happy it happend before I tried to actually shoot it because it was clearly not strong enough but part of me wanted try it out anyways even if I get hurt a bit :S

    I'm disappointed only because I spent a whole day with it (even though it would've been 3 hours or less if I had the tools at hand) and it broke on me. I took some pictures while it was in progress and im sad I Didnt take one when it had the tubes and the string... even if it was crappy IT LOOKED SO COOL :D

    After i calmed down i started to hack together a VERY primitive crossbow-ish stuff but it was almost dark already and i was tired so i put it away and i'll continue working on it some other time.

    For this project... I dont know... we have no boards that look strong enough and I'm afraid to buy anything because I'm not sure if it would work.
     
  13. Brazilviking

    Brazilviking Thread Hijacker

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    From all the words, I could only keep one thought in my mind....YOU FOUND A SLINGSHOT ON THJE GROUND???
     
  14. BeMahoney

    BeMahoney Builder of things

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  15. AttilaTheFun

    AttilaTheFun New Member

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    I KNOW RIGHT?! :D:D


    We were just walking when i saw something, it was already kinda dark so at first i just had a thougth "Oh God... too much slingshotting, I already see slingshots everywhere" Then BAM i realized it was actually a slingshot.

    I think its a pretty cheap one. The tubes are... not too weak but they're not fast (my 2x2 TBB 20X2cm bandset is much easier to draw yet feels stronger) The plastic frame is broken at the bottom due to the usage of arm brace. I took a picture and I'll upload it when i get home.

    My girlfriend was watching me for a while then just said "Ati, I'm happy for you and your slingshots but if you find slingshots on the ground just because you love them so much, please start loving diamonds and gold and piles of money!"

    Yes BE... Signs:D Now the only thing i need to find is a huge roll of TBG :D
     
  16. Ghosth

    Ghosth Over the hill but still swinging!

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    Instead of a slingshot crossbow, where either the lock end or the forks end has to slide on a frame.

    Consider instead a basic slingshot rifle being a lenth of pipe or wood with fixed forks on the far end. Your end can be plain, stocked, or have just enough of a bend to rest the heal of your hand on when you have it drawn. No moving parts, simple, it gives you very nice accuracy and power. Its also very quick and easy to make, experiment with.

    Like this one

    [ame]http://www.youtube.com/watch?v=rbfNyMNi20U[/ame]

    Mine is made out of PVC vs Aluminum tubing with a short curved piece of 3/4 PVC conduit as the forks. But otherwise looks like the one in the video. It shoots like gangbusters, highly accurate and powerful. When I went to Walmart looking for thera band all I could find was green heavy duty not gold. It has single bands 10" long about an inch wide leaving probably 9" actual. Mine is also a bit shorter at 3 foot draw length vs 4.
     
    Last edited: Sep 22, 2013
  17. Slagskimmer Mike

    Slagskimmer Mike thinks TBG smells better than roses

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    @BV---+1
    I shot the corn on the cockatiel and the villagers ran away......ROTFL.

    Pretty graphics there Be, I would have missed them too.


    I like the design, it does remind me of the Raptor.
    I think building it will open up a multitude of new ideas, so you should go for it.
    Everything I make is really a prototype--its never done before I get ideas I like better.
     
  18. AttilaTheFun

    AttilaTheFun New Member

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    Thank you, that is an interesting design and I will most likely build one sooner or later but for now:
    I don't know I always liked things that's not perfect, that unusual, things where functionality is not the first priority. If a good shot was all I wanted, I would have welded together some pipes and made a design similar to what you have shown me or I would use simply a slingshot. But this means much more to me, getting an idea making it, experimenting, getting experience. The whole process itself means so much fun and even though it was flawed and later broke, drawing that "bow" was a very good feeling, seeing the parts move and everything. I really don't want to compare myself to great inventors and I do this only for fun instead of perfecting anything but something doing the job fine doesn't mean you cant look for other way (Light bulbs and electric lighting is incredibly complicated compared to lanterns and has much more part where it can fail).
    Anyways I'm not trying to conflict you or anything just trying to express why I do things that is flawed even by design :) Thank you again for that vid!

    Thank you! Yes, after I fought the disappointment I got some enw energy and I'll continue the project next time I can. I'll get some strong Plywood that might to the job :)

    _________________________________________________________________


    Ohh and some pictures. First the slingshot i found :D
    [​IMG]

    And here's a pictures of what i made. Sadly it's half-done and I didn't make one after it had hook-screws, the tubes and the string. (It seems that the metal connection comes in contact with the arms but it had a small plastic pipe so it didn't really and the friction between the wood and the pipe was very small. Please consider i never really worked with wood before so its all strange and new to me I meant this to be a prototype and was more than happy with the result :)
    [​IMG]
     
  19. Arturo Borquez

    Arturo Borquez Administrator

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    well, mmmm in your design there is (almost) no speed multiplication to counterweight the lever efficiency (<<1 maybe equivalent to a very heavy rubber) ... it should work but I believe slower than a normal slingshot for the same pull and draw ... watch out that there is no synchronization mechanism between the levers, could be dangerous if there it is a rubber force unbalance ... the raptor (search Jeorg's videos) comes with all the bells and whistles (multiplication, synchronization ... etc, but very expensive) ...
    Cheers
    Arturo
     
  20. WildBill

    WildBill The Silly Song Guy

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    I agree with Arturo- there's no real multiplication of velocity in the design. It will work, but it won't grant you more force.

    Consider the jawbone of a snake. Snakes have an extra bone in the jaw that allows for greater extension- the quadrate bone:

    http://www.peteducation.com/images/articles/ill_snake_jaw2.jpg

    Using longer actuating arms combined with the 'second snake joint' would give the multiplication you are seeking, though at a price. You would have both a longer draw as well as more fail points in the structure. I can try to draw for you the joint I'm thinking of if you like, but I'm not good at computer stuff so I'll have to do it by hand and scan it. Just let me know.

    -Wild Bill
     
    Last edited: Sep 22, 2013