# Quick theraband advice needed!



## flare3113 (Dec 3, 2013)

Hi all,

I am developing a slingshot/crossbow machine that is going to fire squash balls for a uni project. I have read a lot about theraband gold, and I just wanted a few things cleared up.

1. If theraband gold has the most resitance per extension, how could theraband band black or any other type be "faster"? If I wanted to fire a squash ball as far as possible, which one should I go for?

2. I don't fully understand the effects of folding or doing multiple layers, is it basically the same as having two bands. E.g, 2 layers of theraband gold will have twice the force of one layer of theraband gold

3. I have read some people using speargun rubber, and other types of rubber instead of the theraband gold. Why would they do this? Is that because they can have more force per extension but are more expensive?

My main aim is to optimise the power/distance I can fire the squash ball. Any help is greatly appreciated!


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## Imperial (Feb 9, 2011)

are squash balls the same as racquetballs ? i have no idea on the size and thickness of them. and are they light weight also ?


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## Sunchierefram (Nov 16, 2013)

Well flatbands are typically faster than tubes. And thinner rubber contracts faster, meaning it'll shoot faster. So as TBB is thinner than TBG, several layers of TBB that's the same thickness as 1 sheet of TBG would shoot faster than the 1sheet of TBG. On the downside, they won't last as long.


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## Bajaja (May 13, 2011)

But TBBlue or TBBlack are definitely worth the speed!


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## HarryBee (Jun 29, 2013)

flare3113 said:


> Hi all,
> 
> I am developing a slingshot/crossbow machine that is going to fire squash balls for a uni project. I have read a lot about theraband gold, and I just wanted a few things cleared up.
> 
> ...


Speargun rubber will be slower ( because of its thickness ) , but it can throw a heavier weight than, say, single TBG. But the single TBG ( because of its relative 'slimness' ) retracts faster - as long as its only throwing a much lighter weight. If you get three or four single TBG strands, now you,ve got the speed AND the power 
Think of it this way. If you want to throw a baseball fast - get a baseball pitcher ( TBG ) If you want to throw a 16lb iron shot - get a shot putter ( speargun rubber ) ! Lol.
Some people use very heavy rubber in the ( mistaken ) belief that if rubber is very hard to pull it will shoot any ammo at the fastest speeds. one learns otherwise on this forum.


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## myusername (Oct 5, 2013)

thinner rubber contracts faster, so multiple layers will shoot lighter ammo faster. if the ammo is heavy it doesn't matter as much.


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## ruthiexxxx (Sep 15, 2012)

I don't recall squash balls being very heavy so I'd be inclined to try Theraband Gold...maybe 25mm doubles. Presumably if it's a machine and not hand held you can have a pretty good length to play with. I think heavy tubes would be unnecessary unless you want the option of shooting heavier ammo as well.


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## Aussie Allan In Thailand (Jan 28, 2013)

Well I have on a gift Slingshot very wide Golds Gym Blue band set up.

This is two pieces laid one on top of the other; then carefully folded to make a single band each side.

I have been led to believe this material is equivalent to Theraband Black in thickness.
So a comparrision can be made.

My usual set up is either doubled .04 latex, or triple TBG: which drawn to my usual 550% plus a bit for the TBG for the same ballistics as the latex.

This is very difficult for most to draw very much at all.

I am fortunate by my carreer, and some very hard work, to be quite strong for my wirey/slight stature.

Now the Golds Gym Blue bands actually are quite noticeably much easier to draw.

Drawing them to a bit over 600%; gives me identical ballistics as the heavier to draw band sets.

Life expectancy according to what both myself, and yourself have been told, should be much shorter.

BUT this is not my experience.

Here in the tropics of Thailand, where bands generally tend to be damaged over time a bit faster than cooler climates.

The gift slingshot bands have held up to a lot of use, over now I think almost 18 months.
Where my other band sets have pretty much all had to be replaced, given I practice quite a lot.

These show no damage at all.
To a point that I am thinking over time to replace my other band sets with Theraband black.

For interest sake only I normally shoot heavier than many ammo.
And these bands have no trouble shooting fast enough to place 20 gram lead ammo/shot, dead center of the forks, out to just under 12 meters.

I trust my experience is of some assistance; but I warn this is my own personal experience, and it is likely true what the others say regarding band life.

Why I am getting my results here (?)....

I can only guess at a reasonable answer, being I do keep all my slingshots usually in air conditioned comfort when not practicing, or carrying them as I do daily.

A photograph of this slingshot, and several others I own, is at my facebook gallery. 
At http://www.facebook.com/photo's

From memory the slingshot with the band set up I am speaking of, is the natural at the top left.

Cheers Allan Leigh in Thailand


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## Aussie Allan In Thailand (Jan 28, 2013)

Sorry, midway through putting the facebook address up; things mucked up.

Anyway if interested the full web address is, provided I get it correct:

http://www.facebook.com/Allan.Leigh.9?ref=tn_tnmn

Cheers Allan


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## ash (Apr 23, 2013)

flare3113 said:


> My main aim is to optimise the power/distance I can fire the squash ball. Any help is greatly appreciated!


Are there any restrictions on the amount of rubber, how you arrange it, draw length, temperature, manner of loading/drawing etc?

You could quite easily roll up two whole 5-yard lengths of TBB and make a monster catapult if there are no particular restrictions. Or arrange multiplying mechanisms to turn thrust into even more speed. Loads of ways.

Where are you? Australia?


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## flare3113 (Dec 3, 2013)

ash said:


> flare3113 said:
> 
> 
> > My main aim is to optimise the power/distance I can fire the squash ball. Any help is greatly appreciated!
> ...


No restrictions. The machine I am creating has to fit within a 0.5m cube, but with regards to elastic I can use however much I want as long as I dont go over my price budget of £50. The machine cannot use hydraulics or neumatics, so mine is basically a bow/ballistae looking thing, which will use elastic to fire rather than torsion ropes on the firing arms.

A monster catapult is pretty much what I am after. What mechanisms come to mind when "turning thrust into speed"? so far i tried to maximise how far the elastic can be drawn back, and how small I can make the length to start with (so maximum extension). I am already using a winch to pull back the firing cup which will house the squash ball.

So the general consensus is use as thin a rubber as you can (TBBlack or Blue), as many multiple layers as you can, and as much extension as you can?

Does anyone know at what extension on of the therabands snap at?

Thankyou all for the responses, they have all been very useful!!

P.S. how do you work out draw force. I have seen people saying "I have used multiple layers of TBblue and this is the same drawforce as TBG but I cant work out how that is possible?


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## ash (Apr 23, 2013)

I only have time for a quick reply, but the mechanism I think you could consider is a multiplying pulley and cable system as used by construction cranes. You see those cranes over construction sites where the hook tackle is suspended by say, six cables. It's actually just one cable wrapped around a series of free wheeling pulleys at each end. One end of the cable is fixed on the boom and the other is pulled by the winch. It gives a 6:1 ratio. I've seen it used in reverse to launch base jumpers as a vertical catapult by using a heavy weight dropping slowly over a short distance. The free end of the cable accelerates at six G. The moving inertial is potentially a lot less than a pair of swing arms.

Can the arms, cables or pouch travel outside the cube in firing?

Have you considered using impact on the rubber ball to increase the energy transfer?


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