# Rule of thumb Deminsions



## Albidge (Oct 30, 2013)

I am getting ready to make my first sling shot from laminated wood. Have not made a sling shot since I was a kid using tree branches and inner tubes back around 1968. Are there any rules of thumb for the size of the sling shot irt your hand. How should I determine the length of my tubing. Any help / tips would be greatly appreciated.


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## Metropolicity (Aug 22, 2013)

It really depends on what kind of slingshot you want to make.

I typically start at looking at how wide your grip is, I do this by holding you index finger and thumb In a "C" shape and then measure that. That should be the middle width of the fork. From there you can measure how wide your palm is, that should determine how long the sling could be and if you wanted a pinky hole or not.

Returning to the fork, if shoot TTF like I do, you want the forks to be a little wider than your grip to get the right clearance. Then decide if you want a tube shooter, flat bands or a combo. If you shoot OTT, your forks can be as wide as your grip.

That's how I start with design.


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## Albidge (Oct 30, 2013)

Thank you for the response. I am going to use your tips for my first attempt. Do you have a rule of thumb for the length of your tube or band. Is there really that big a difference between the performance of bands over tubs?


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## Deano 1 (Oct 11, 2013)

Personally I don't think there is a lot of difference in performance between tubes and bands, it's what you prefer and what you can shoot best. I shoot both and all different strengths but I do have my favourites, depending whether I'm shooting paper or meat. I cut all my elastic at 25 cm.


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## jazz (May 15, 2012)

Hi Albidge,

I do not know about rules of thumb related to your question althought there migh be some.

In order to determine my or anybody else's length of bands (sorry I can not speak about tubes, not enough experience), and in my case it is exclusively Thera-Band Gold (TBG), I first determine the length of the draw. As you probably know the length of draw varies with people but also with the same person if she/he uses various draw strategies: somewhere at the chin, corner of the mouth, ear lobe, end of shoulder (as in my case) or even far back like in the butterfly/albatros style.

So, whatever the given lenghth of draw is, you simply divide, say, 4, 4.3, 4.5, 5 tor even more which is a rather large stretch ratio of TBG. I do my cut so that I divide my 96 cm of draw with ratio of 4.3 which gives me 22.3 active band length and then I add some 1.5 cm on both ends for tying to the pouch and to the forks which adds up to some 22 + 3 = 25 cm cut.

I could use stretch ratio of 5 which is even more economic and powerful (96/5=19.2 active length + 3cm = 22cm) but this steretch ratio leads to shorter band life and I can not afford to break TBG so often.

The other thing to consider is what you want to shoot and for what reason. If you shoot 7mm steel or 11mm lead is not the same thing. Their weight is very different so you would need wider bands (or multiple bands) for the latter case if you want decent speed and power.

If you are new to all this then maybe the best thing to do is that you decide on where you want your draw to end, measure that, divide it by any number (stretch ratio) you deem appropriate, cut any tubes to that matter, band the frame and se what you get. Maybe you can shorten the bands/tubes to gain more power or you can add more rubber (wider rubber, stronger tubes) or both.

Sorry if my answer is not very precise but nothing in this sport is; I am sure that if you try you will eventualy come to the lengths and types of rubber best for you.

cheers,

jazz


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## Albidge (Oct 30, 2013)

Jazz and Deano 1: Thanks for your responses. I am going with tubing for my first run since I have access to it. The measurement formula from Jazz is a great. I will use it as my starting point. Appreciate the advice and insight from both of you. Still drawing my prototype before I start cutting wood. Metro Grade provided me the frame measurement formula. When I get done I will let y'all know how it worked out.....Or if I hit anything I shouldn't have


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