"Double tappered" bands

Discussion in 'General Slingshot Discussions' started by Arturo Borquez, Aug 29, 2012.

  1. Arturo Borquez

    Arturo Borquez Administrator

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    Hello all, (excuse me the typos, I speak Spanish)<br>I've just subscribed and new to slingshot world. I have seen all Jorg's videos (amusingly inspiring), my name is Arturo from Chile (South America). Few days ago I made my first slingshot, and after several hours of practice (1000 shots or more?) I am hitting 10cm diameter at 10 meters consistingly, my background is archery and I have a crossbow. My slingshot is awful ugly, at the beginning bands lasted no more than 50 shots before tearing. Today I am very happy with this bands (500+ shots) and no signs of tearing (only a little bit abrasions at the "low" band, this bands are double TBG equivalent (Cando, 1/6 price TBG) "Double tappered" and gives me a very good feeling at 1 meter draw (39 inches just above my shoulder) and is fast enough or better than my crossbow I believe 250+ fps (I don't have a crony). I am shooting all kinds of ammo (marbles and steel, very light to heavy). The dimensions of this bands are: 16mm at fork to 20mm at 120mm (length from the fork), a straight region of 40mm (20 mm wide) and the back region of 120mm to the pouch which ends 16mm wide, I use two bands per side. Does anybody did something like this?, I will be grateful to hear comments, experiences ...<br><br>Best regards<br>Arturo
     
  2. Meckillim

    Meckillim New Member

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    Hey Arturo. I have made three slingshots so far. two as gifts and one for myself. Unfortunately I broke my own by shooting a much much much too heavy lead ball <img src="http://illiweb.com/fa/i/smiles/icon_cry.gif" alt="Crying or Very sad" longdesc="11"> but they were all rigged with two bands per side TB gold cut to dimensions i obtained using Joergs Calculator. I only wish I had put three per side for more power. Right now I dont have any hard wood to build slingshots from so i just draw up blueprints <img src="http://illiweb.com/fa/i/smiles/icon_smile.gif" alt="Smile" longdesc="2">
     

  3. Arturo Borquez

    Arturo Borquez Administrator

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    Thanks Meckillim for the feedback,<br>I also used Jeorg's calculator at the beginning, and choose a 22mm to 16mm tapper, 24 cm length, 2 per side, but I feel the bands where a little bit hard to pull and not much fast as I expected (same compliant, speed bellow my crossbow I guess) and I was getting a heavy handslap, so I attached to it a wooden "hand protector". Now with the shape of the bands that I've described the slingshot is very quiet and the draw is very smooth, no doubt that it performs better speed and tearing is gone !!!, (and hundred of shoots with very light ammo 8mm marbles, blazingly fast) maybe I can shoot a lot more. That intrigues me, if this "double tappering" shape of the bands is the cause of duration and speed increase ???<br><br>Best regards<br>Arturo
     
  4. Meckillim

    Meckillim New Member

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    Very interesting. You might be on to something big <img src="http://illiweb.com/fa/i/smiles/icon_smile.gif" alt="Smile" longdesc="2"> can i see a picture of the bands? Where did you say you got the bands?
     
  5. Arturo Borquez

    Arturo Borquez Administrator

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    Yes I have the pics, but I never before uploaded data to a site (I am 62 years old, not an internet geek), can you recommend me where I can upload? ... I purchased the band roll (10 meters) at a local fitness store, Cando brand, they claim are 100% TheraBand compatible and the same colour equivalence, but 1/6 the price, at the beginning I was worried about quality (as my first bands lasted less than 100 shots), but now I am almost sure that with this shape there is much less "destructive" strain at the puoch and the same or better advantage of speed of deep tappering ... meanwhile 100 shots more !!!
     
  6. Meckillim

    Meckillim New Member

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    Ok, when you want to upload images go to the bottom of the page where you type your message, then click on the sixth button from the left (above the massage box). Then click browse. (this will open your documents. The picture must be on your computer in the documents) Then click on the picture and click "open" and then click the middle option where it says "copy". After you have done this right click inside the message box and paste the adress you copied. Then press send (along with a message if you want) and youre done! <img src="http://illiweb.com/fa/i/smiles/icon_smile.gif" alt="Smile" longdesc="2">
     
  7. Meckillim

    Meckillim New Member

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    <a href="http://www.servimg.com/image_preview.php?i=10&u=17753487" class="postlink" target="_blank" rel="nofollow"><img src="http://i35.servimg.com/u/f35/17/75/34/87/purple11.jpg" border="0" alt=""></a><br><br>Here is my slingshot before i broke it.<br><br>Also, I forgot, you must click "Host it" after you have clicked "open"
     
  8. Arturo Borquez

    Arturo Borquez Administrator

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    I cannot post images here for 7 days ... maybe this works<br><br>img129.imagevenue.com/img.php?image=283242101_slingshot_122_1042lo.jpg<br>img37.imagevenue.com/img.php?image=283243356_band_122_79lo.jpg
     
  9. Arturo Borquez

    Arturo Borquez Administrator

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    Meckillim,<br>copy paste in your browser an prepend the http stuff, first picx shows the slingshot the ammo and a can soothed with 11mm steel ball, the second picx show the layout of the bands, you can observe the abrasion lines in the bottom band (enhanced the view of them with talcum) ...<br><br>Best regards
     
  10. Arturo Borquez

    Arturo Borquez Administrator

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    Meckillim, thanks<br>Ohh it did work !!! btw it's a pity your broken slingshot was very beautiful ... mine you can see is ugly, but the bands are out of question ... shooting this afternoon till sunset ... I've lose the count, I guess I am reaching 1000 shots !!! and no signs of tearing !!! <br>The picture isn't very explicit about the shape of the bands, so below are the dimensions (not true scale) <br><br>Best regards
     
  11. Meckillim

    Meckillim New Member

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    Haha thank you Arturo. It was beautiful but the handle gave me blisters. Yours looks more comfortable at least <img src="http://illiweb.com/fa/i/smiles/icon_smile.gif" alt="Smile" longdesc="2"> I was wondering where you get your ammo. Theraband and wood was cheap where i bought them but ammo is expensive. I live by the sea so i just collect rocks that are somewhat round. Still they are inaccurate and curve in flight
     
  12. FORTUNENGLORY

    FORTUNENGLORY New Member

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    Great idea with the bands. I was thinking about trying double single tapered bands attaching them in opposite directions on each side of the slingshot. Getting the best of both worlds at each end of the release.
     
  13. Arturo Borquez

    Arturo Borquez Administrator

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    Ha ha it's a zombie handle but fits very comfortable to my hand, well ALL here in Chile is from China, I bought at a local rep shop a box of 100 ball bearings 11mm for about US$ 20, the brand is KML, the marbles are very cheap 1 US$ per 100, sorry the administrator say that a can't post web sites URL's <br>
     
  14. Arturo Borquez

    Arturo Borquez Administrator

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    The concept idea is very simple, maximum strain is transferred to the pouch (which by definition has a small contact area), with tapered bands this effect gets worse as the extra elongation near the pouch makes this area smaller so the shear stress will be greater. I thought that tapering also the fork side (which has a greater contact area) would relief the strain at the pouch (maximum elongation divided by two), moving the "hard" elongation section to the centre of the band, I believe this theory works, and this shape is also lighter than the "traditional" taper (less inertia), that's why the increase of speed ...
     
  15. DaveSteve

    DaveSteve New Member

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    <table width="90%" cellspacing="1" cellpadding="0" border="0" align="center">
    <tr><td><span class="genmed"><b>Arturo Borquez wrote:</b></span></td></tr>
    <tr><td class="quote">The concept idea is very simple, maximum strain is transferred to the pouch (which by definition has a small contact area), with tapered bands this effect gets worse as the extra elongation near the pouch makes this area smaller so the shear stress will be greater. I thought that tapering also the fork side (which has a greater contact area) would relief the strain at the pouch (maximum elongation divided by two), moving the "hard" elongation section to the centre of the band, I believe this theory works, and this shape is also lighter than the "traditional" taper (less inertia), that's why the increase of speed ...</td></tr>
    </table>
    <span class="postbody"><br><br>Interesting thought. I don't have a chrony to test but I'd like to hear Joerg's opinion on this.</span>
     
  16. Arturo Borquez

    Arturo Borquez Administrator

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    Well first signs of tearing (little scratches) near the pouch tie both sides (symmetric wearing, good !!!), I lose the count until yesterday I believe 1000+ shots and this morning 200+ shots, so I will count until the first hole, I am very pleased with this layout ...<br><br>Best regards
     
  17. Arturo Borquez

    Arturo Borquez Administrator

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    One band broken in less than 50 extra shots after first signs of tearing, same a with prior bandsets, so when tearing start bands die comes quickly. I've just made a new bandset but a little bit stronger and 1cm shorter, 24.5cm (bands tied), and did a round of 20 shots. It performs very accurate and consistent (hit 80%), but I will need to slow down, feeling a little pain in my right hand (release).<br>I did some slight changes in the attachment to the pouch, a little bit less pre-stretch and a a little bit less tension when warping the tie especially near the contact with the band. I will see, this is a kind of art, cut and try, the fork end does not develop any problem, if I can get 1000+ shots I am more than satisfied. Next week when I will be allowed to upload pics I'll show the failure of the first set of band with this layout, maybe someone can help to improve my assembly technique.<br><br>One question to the masters of the forum : It is possible to lube the pouch tie (a little drop at the contact between the band and the tie to decrease attrition) ??? if so what kind of lube or brand I can use ???
     
  18. Saderath

    Saderath Senior Member

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    I always use talkum powder just before i attach the pouch.
     
  19. Arturo Borquez

    Arturo Borquez Administrator

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    Many thanks Saderath, I will do that with the next bandset ...