# Alternative pouch design: "dog bones" (i.e. without punched holes)



## Crac

My question is this, "Why are we still punching holes in the pouch?"

Wouldn't a design using an "H" shaped double dog bone be better?

-The elastic would be swept straight back and tied to the "outside" of the dog bone tabs. (Not doubled back through a hole... hence saving HALF the elastic at attachment)

These tabs could be cut with a MUCH larger radius so the stress concentration factor should be much much lower. The load distribution should be better since the leather has nowhere to go (not edge-on loading), the pouch is in pure tension. And this design should also be a little lighter since it can be both shorter in length and narrower in width!


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## B.P.R

Pictures paint a thousand words......


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## pop shot

Do it, test it, report back


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## Quercusuber

Looks intersting...Can you make a sketch of your idea?? 

Cheers ...Q


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## bigron

where are the pictures or video :banghead: :stupidcomp:


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## kobe23

i see your point. i remember some used them on the milbro square solids.


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## Crac

<img>http://s24.postimage.org/5n2gw0djp/Pouchwithtabs.jpg</img>


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## Rayshot

Crac said:


> <img>http://s24.postimage.org/5n2gw0djp/Pouchwithtabs.jpg</img>


Yes, test it and tell us how the whole procedure and functionality of the method works.


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## rockslinger

I've made them like that in years past especially when I couldn't decent leather ie, holes would tear out. They worked fine for :wave: me.

Probably tried most everythimg in 60+ years making slingshots off and on.


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## Viper010

i cut my pouches with 'fish tails' on the end n tie the bands on with a constrictor knot. like you, i had the idea itd save weight on the attachments.
works a treat for me, single bands, doubles or triples alike.
but i do find doubles or triples a bit more of a hassle to tie than singles.

cheers, remco


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## Rayshot

Would you guys be willing to post a photo of one you have tied? Please? I would like to see how you guys are tying them on.


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## DaveSteve

Rayshot said:


> Would you guys be willing to post a photo of one you have tied? Please? I would like to see how you guys are tying them on.


I found one on this forum.

The leather here seems to be looped through the rubber bands and then folded back and tightened.

I guess when you use flatbands or tube you just put leather and elastic together and tie a knot.

http://slingshotforum.com/gallery/image/1799-elktine-linked-fitchifile/


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## Rayshot

DaveSteve said:


> Rayshot said:
> 
> 
> 
> Would you guys be willing to post a photo of one you have tied? Please? I would like to see how you guys are tying them on.
> 
> 
> 
> I found one on this forum.
> 
> The leather here seems to be looped through the rubber bands and then folded back and tightened.
> 
> I guess when you use flatbands or tube you just put leather and elastic together and tie a knot.
> 
> http://slingshotforum.com/gallery/image/1799-elktine-linked-fitchifile/
Click to expand...

Good find. I don't recall seeing that. Though that doesn't mean I didn't, but may mean I didn't notice the attachment method.

I am still interested to see the dogbone pouch method tied to a flatband. In the above link photo, the looped elastic is a reversed, yet with simpler dynamics of the way a latex band and leather pouch with holes works,.


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## Viper010

DaveSteve said:


> Rayshot said:
> 
> 
> 
> Would you guys be willing to post a photo of one you have tied? Please? I would like to see how you guys are tying them on.
> 
> 
> 
> I found one on this forum.
> The leather here seems to be looped through the rubber bands and then folded back and tightened.
> I guess when you use flatbands or tube you just put leather and elastic together and tie a knot.
> http://slingshotforum.com/gallery/image/1799-elktine-linked-fitchifile/
Click to expand...

good find, intresting to see indeed! but this is not how i do it.... i just cut a rectangular patch of leather, usually some 9cm(3 1/2") by 2cm(3/4"), cut some notches out the long sides near the end, wrap the rubber round it lengthwise n tie a constrictor knot. evrything is 'in line' with eachother.

i will try to post pics asap. but since i dont have a computer (im on my iPhail) thats a little difficult (ie ill have to do it at a friends house)


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## rockslinger

Rayshot said:


> Would you guys be willing to post a photo of one you have tied? Please? I would like to see how you guys are tying them on.


This is how I do it.














I've never needed to flare or fishtail the ends.


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## Crac

^ Yeh, that's it.

The elastic on the back and everything straight. First class job.


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## bigron

still no pics


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## mopper

That is a very interesting method with a lot of inherent advantages ... no tools and extra work for holes in the pouch, better stress line dispersion, no doubled up rubber which means less weight which in turn means better speed and less handslaps.

@ rockslinger:

Which side of your pouch is the "ammo" side? I always use the smooth side for holding the ammo (= inside of the pouch) and the rough side for gripping (=outside of the pouch).

I ask because judging from your pics you are either doing it the other way round or you attach the bands to the smooth "inside" of the pouch, which I have heard can cause problems with accuracy. I also imagine the bands would slip more easily on the smooth leather surface ...?


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## Viper010

i do it more or less the same as rockslinger, only i do fishtail the ends to prevent slippage n i use a constrictor knot instead of a rubber tie (even further weight reduction + i find it easier to do)

tnx for posting the pics rockslinger, worth a thousand words!
cheers, remco


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## BrokenPins

This is pretty interesting...


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## Crac

Maybe some 'hard science' will be of some interest to a few people?



















The Orginal extract is from:
Young, W. C. and Budynas, R. G.: Roark's Formulas for Stress and Strain, McGraw-Hill, Seventh Edition 2001.

And the orginal references are:

1. Peterson, R. E.: ''Stress Concentration Factors,'' John Wiley & Sons, 1974.

10. Baratta, F. I.: Comparison of Various Formulae and Experimental Stress-Concentration Factors for Symmetrical U-notched Plates, J. Strain Anal., vol. 7, no. 2, 1972.

5. Flynn, P. D.: Photoelastic Comparison of Stress Concentrations Due to Semicircular Grooves and a Circular Hole in a Tension Bar, ASME J. Appl. Mech., vol. 36, no. 4, December 1969.

25. Heywood, R. B.: ''Designing by Photoelasticity,'' Chapman & Hall, 1952.

And the anyone who does want to crunch a few numbers: The stress concentration factors are around 1.06 for the dog-bone idea, vs 3!!!!! for the hole. Hence the width for me are 8mm vs 23mm...


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## Knotty

Crac, count me among the "few". Thanks for the technical info.


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## Flatband

The cleanest method I ever saw for attaching flatbands to a pouch was used by a 50's slingshot called "The Perfect Grip" slingshot. I have one but it is put away up in the attic. In essence what it consisted of was a regular straight leather pouch with the ends of the rubber strap glued somehow to the leather. It actually looked as if the rubber was fit in between the thin leather pouch. This might be right up your alley Rayshot with you using those laminated pouches. Maybe try to sandwich a band end between two thin strips of leather and glue it up. I tell ya it was a very streamlined attachment! Very clean and neat! Flatband


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## Imperial

i miss the simplicity of slingshots . . . this is too :nerd: elaborate for me . guess i need to google for a book entitled," slingshots for dummies " :banghead: . letters should only be used for spelling, :angry:


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## Rayshot

Flatband said:


> The cleanest method I ever saw for attaching flatbands to a pouch was used by a 50's slingshot called "The Perfect Grip" slingshot. I have one but it is put away up in the attic. In essence what it consisted of was a regular straight leather pouch with the ends of the rubber strap glued somehow to the leather. It actually looked as if the rubber was fit in between the thin leather pouch. This might be right up your alley Rayshot with you using those laminated pouches. Maybe try to sandwich a band end between two thin strips of leather and glue it up. I tell ya it was a very streamlined attachment! Very clean and neat! Flatband


@Gary; Very interesting Gary. Thanks for the heads up. The only thing I would feel there would be a loss of money and a pouch is when the latex fails. I love to use my pouches over and over again. I have some that have gone through easily 10 bandsets. I have so many that it is hard to test any one pouch long enough to have used more than that many band sets on one pouch up to this date.

Re, Dogbone pouch; It has some good aspects to it. True there is no need for a hole but I definitely don't have any more weight with a holed pouch and the dog bone pouch is not shorter or less leather used. And the band extends towards the fingers holding the pouch, negating a pouch length conservation. Width conservation is not any more advantageous with the dog bone cut. Unless referring to right where the tie is.

As for the way I tie my bands, though some may save elastic. The saving on elastic by the attachment method is essentially negligible too.

I thought about this method some time back and I did make a pouch just like the dogbone. I was trying to find a better method than a holed pouch. I tied it up used it and personally found, (note, personally) found the holed pouch far more redeeming. I threw the dog bone one away. That is why I almost didn't remember it. All that being said. I am not knocking any one here. Just stating what I observe and have found.


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## Crac

Rayshot said:


> but I definitely don't have any more weight with a holed pouch...


lol yes "lightening" holes.... and when I stop laughing....


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## Susi

The common sence physics of this dog bone method is super...why didn't we think of this before? Great post, will try this on two SSs I'm making now..leather thickness will be important or maybe to shave down the leather with a razor blade or abrading it thinner with 60 grit sand paper on the tie ends to make it thinner there. I have been trying a "wrist rocket" (tube elastic) plastic fastener copy, made from a plastic masonry anchor with the open end cut down a bit. The anchor is split at the point end...through the split I put the pouch hole...the grooved end of the anchor goes inside my tube elastic band over which is tied with thick nylon sewing thread in a fisherman's knot around the union of the anchor and tube. This is heavy due to the plastic masdonry anchor (again, wrist rocket style) , but is a good way to fasten the tube to the pouch and I don't like it nearly as much as your idea of the fishtail tie posted on this thread using flat bands insteadof surgical tubes.

Flatband's suggestion of a laminated pouch integral with the flatband elastic...great idea.

In addition, since I can't get Theraband elastic and office supply bands are not particularly good, I am forced to use only surgical tubes here in bananaland, if I can get some theraband elastic I'd love to try (but can't) Flatband's suggestion of putting a continuous band laminated between two pieces of thin leather to make a continuous band inside the pouch material itself. Darned if this isn't a slick approach!!! I've simply GOT to start a club here in Ecuador so I can import a huge roll of TB (likely gold) and start making bands with pouches for club members. Using contact cement to bind the leather laminates and elastic together might be the method...if the contact cement solvents don't degrade the latex...which in itself is an organic compound. Trial and error, eh? The stress on the elastic at the pouch will be eliminated or nearly so using Flatband's suggestion. Oh the misgivings of tubes!


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## pop shot

I still don't see how this is better than a holed pouch. Harder to tie accurately and it could 'pocket' and wrap around the ball. But if it works for you, go for it.


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## Gardengroove

Me too. It's quite interesting though. But I leave the pouch making to the pros. Never had a prob with a pouch from Ray. After hard use of like 10 bandsets I don't care if the pouch is breaking then.


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## Crac

The difference between theory and practice is bigger in practice than it was in theory...

All quantified contributions warmly welcomed and greatly appreciated. (Please include reasoning.)

I'm interested in the idea of gluing as in tension only the width and thickness are available, whereas in a lap-joint width times length can be used. While the shear strengths will be lower the available length is MANY MANY times greater than the thickness. For example 10mm length vs 0.636mm thickness = 15.75! even at 10% of the strength the joint is 1.5 times stronger!

For clarity I will add: My initial thought was a thin 8mm wide tab, of length 15mm. Thus minimum weight. (maybe not worth using)

However: A stacked laminate using a mono-band with the pouch glued in the middle is interesting. -I wanted to try something similar and *just* use two pieces of duck tape to reinforce the elastic... But I think this is a bad idea.

I can't help think you might be better making the whole thing out of latex! (Latex band, latex pouch and latex glue) I would be A LOT happier with a single material... But I think this idea is only for world record attempts. (I might try this one)


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## Arturito

Nice idea guys and girls !!! I will test it right now !!! thanks for the topic Crac !!!


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## Arturito

and thank you rockslinger for showing us how to do ... it works great, just tested some shoots !!!


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## mrpaint

Thanks for this post, this is going to help me out immensly! I have been using an awl to hand punch holes in my leather pouches and it doesnt work too good, not to mention its a PITA. Im gunna give this a whirl and ill let you know how successful I am.


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## Arturito

here are some test shoots done with this pouch






feels a little bit different as is it a bit concave, but very easy to get used ...

thanks again rocksliger !!!


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## Tex-Shooter

This is a good method! Ivan and myself did this in the early 90's. Don't know if I have a picture or not, but will look. -- Tex


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## Tex-Shooter

We called this method a plug tie and we tried it on both tubes and flats. Here are two pictures I made for a post in 2010. -- Tex


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## Arturito

Tex-Shooter said:


> This is a good method! Ivan and myself did this in the early 90's. Don't know if I have a picture or not, but will look. -- Tex


Done yet 200+ shoots there are not signs of tearing or abrasion at the tie, I will report how much the bands lasts ... thank you for sharing the pics ...


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## Knotty

Tex-Shooter said:


> We called this method a plug tie and we tried it on both tubes and flats. Here are two pictures I made for a post in 2010. -- Tex


Damn Tex. I was going to experiment with that concept this weekend. Thought it would be such an original idea. Of course, you beat me to it...by a number of years! LOL


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## Arturito

After 200+ shoots, over 500 since using this attachment method appeared the first tear (the little hole at 35-36 mark) in the band, BUT it is not related to the tie to the pouch, summary I am very satisfied with this pouch style ...


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## All Buns Glazing

Now a bit of time is passed, and Arturito is still using it for his butterfly videos, have many others using this with success?

I'm interested in using the plug 'n' tie method outlined by Tex because I'm a tube man, Ski-Ba-Bop-Ba-Dop-Bop.


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## treefork

zee bop


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## DaveSteve

rockslinger said:


> Rayshot said:
> 
> 
> 
> Would you guys be willing to post a photo of one you have tied? Please? I would like to see how you guys are tying them on.
> 
> 
> 
> This is how I do it.
> 
> 
> 
> 
> 
> 
> 
> 100_1033.JPG
> 
> 
> 
> 
> 
> 
> 
> 100_1034.JPG
> 
> I've never needed to flare or fishtail the ends.
Click to expand...

I do mine recently like this with flatbands and single tubes.

A soft leather and a tight constrictor knot works great.

I like it.


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## Crac

I found this way others might be interested:

http://slingshotforum.com/topic/2228-mexican-style-chained-rubber-bands/page-4#entry26111


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## CCHGN

Crac said:


> The difference between theory and practice is bigger in practice than it was in theory...
> 
> All quantified contributions warmly welcomed and greatly appreciated. (Please include reasoning.)
> 
> Ok, how about a slit on each end of a rectangular patch and run the flat band through continous? No tying at all( except at the SS).


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