# Theraband formulas



## flippinout (Jul 16, 2010)

I have been using tband gold and like it alot. But i have noticed that a lot of folks are using the black, blue, and green in rather large widths folded over. I just got some blue and black from a friend who is a physical therapist and it feels a lot different than the gold. My question is this:

For the black, blue, or green- what widths and length are you using for traditional draw length vs. butter fly?

Does anyone have formulas for the differing bands? What 'power' are you getting out of each formula and what ammo shoots best.

I would simply experiment till i found the right combo, but i have very little material or time to spend.

Any help or pointers in the right direction would be great.

Thanks


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## whipcrackdeadbunny (May 22, 2010)

Look at ZDP's band charts, that should help. And pick a style and intention (hunting or targeting) and that should help you specialise.


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## flippinout (Jul 16, 2010)

I may not have been clear with what i am asking.

I am looking for the cut/taper of each colored band that folks are using. ie. black theraband, folded, 1.5" x .75"x 10"-- as an example.

What tapers work best for the various colored bands in a folded over configuration.

It matters not whether for hunting or target at this time- i just want to be able to experiment with the blue, black, and green i have without lots of trial and error.

So, does anyone have a formula or pattern they use for the above described bands? If so, what ammo and style shooting does your specific formula/pattern work best for?

Thanks again


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## Deimos (Dec 24, 2009)

I use silver thereband , 3cm to 2 cm tapered over 23cm total lenght.
Perfect target bands for up to 10 meters


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## Frodo (Dec 19, 2009)

I use TB black 30/3-2 but when it's cold i use 30/4-2


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## flippinout (Jul 16, 2010)

Thank you.

Anyone else have a favorite cut?

Butterfly?

Heavy ammo vs. target?


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## Brooklyn00003 (Feb 28, 2010)

I have tried butterfly with thera band gold 30 cm -1.6cm to 0.6cm. still great power !!! 
i used 9.5mm steal


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## whipcrackdeadbunny (May 22, 2010)

I use a double 2 cm straight cut, works just fine up to about 50 mtrs; it might go further, I haven't tested. Silver band or gold.


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## JoergS (Dec 17, 2009)

Use your favorite Thera Gold as a starting point.

For the other Thera types, use this multiplicators:

Yellow = Gold * 7
Red = Gold * 6
Green = Gold * 4
Blue = Gold * 3
Black = Gold * 2,5
Silver = Gold * 1,5

I like Gold in 5,6 cm x 3,6 cm x 23 cm (cut size, effective size 20 cm). This way I get six full strips from a single 23 cm sheet.

I usually cut two strips of 2,8 cm x 1,8 cm per side to get to that dimension, because it does look more neat than folded bands.

So my preferred band in Green would be

Fork side: 5,6 cm * 4 = 22,4 cm (= 2 strips of 11,2 cm)

Pouch side: 3,6 cm * 4 = 14,4 cm (= 2 strips of 7,2 cm)

So I would cut two bands per side, 11,2 cm x 7,2 cm. Band length stays, of course, at 23 cm.

Same strength! Shoots faster, rips earlier, looks less neat.

Whipcrackdeadbunny would use 8 cm straight (2 cm x 4) in green.

Jörg


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## danny358 (Oct 3, 2010)

i have recently been using thera silver cut 36cm long and 3cm to 2cm single layer for butterfly style.drawing out to about 147cm and using .44 lead this seems to have plenty of power for me.i would be interested if anyone has tested similar band and ammo to mine on a chronograph.just see what kind of speeds and ft/lb these band are giving.for normal style i was using fish hunter bands and found these good to.but at the moment im well into butterfly style.


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## flippinout (Jul 16, 2010)

Excellent feedback and a special thank you to Jorg. I will start working with the material this weekend and report back.


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## landus94 (Jan 17, 2011)

Today I decided to improve power in my slingshot so I changed the bands. There were 23cm x 2cm x 1.2cm Gold and I instaled 23 x 2.8cm x 2.8cm Gold. I thought that the power will be increased at least two times. But with new bands the slingshot is only a little bit more powerful and I can't draw the bands as far as using old bands. Now I see, that the geometry of bands is not accidental and it's very important. Thanks to this thread I know that the ratio of width by pouch and fork should be 2:3. Well, at least I know what to don't do in the future







As we all know: If you don't make mistakes you don't make anything.

Greetings and thank again for this thread









EDIT: I've made new bandset - 23cm x 3.8 x 2.5cm and I think it's ok. I had one problem: when I choose the typical way of attachment bands to the pouch (using Band strips) I couldn't draw out the puch even to my face, so I changed the metod of attachment to Type-Z Pouch Attachment by ZDP-189, so the effective length of bands was increased and I could draw out bands farther and the power and speed were improved.


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## ZDP-189 (Mar 14, 2010)

landus94 said:


> Today I decided to improve power in my slingshot so I changed the bands. There were 23cm x 2cm x 1.2cm Gold and I instaled 23 x 2.8cm x 2.8cm Gold. I thought that the power will be increased at least two times. But with new bands the slingshot is only a little bit more powerful and I can't draw the bands as far as using old bands. Now I see, that the geometry of bands is not accidental and it's very important. Thanks to this thread I know that the ratio of width by pouch and fork should be 2:3. Well, at least I know what to don't do in the future
> 
> 
> 
> ...


You can make a bandset bigger harder to draw and slower. OTOH, you can make it half the draw weight and faster. How is down to physics. The answers you seek are in my blog (link).


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## landus94 (Jan 17, 2011)

Uuu, I see lenghty articles about physics and ballistics. Really interesting and useful. Thank you for helping me. Now I see that slingshoting is not as easy as I thought









Good bye, thank you again and greetings from Poland!


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## Qucifer (Dec 27, 2010)

My favorite band set is 4 strips (2 per side) theraband black, 3cm x 2cm x 21cm. Light draw, very fast, and lasts a while, around 300 shots for me shooting 3/8" steel balls.

Q


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## josephlys (May 4, 2010)

How fast are you shooting those 3/8 steel with your set up?


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## Qucifer (Dec 27, 2010)

I cant say for sure since i dont own a chrony, but i would compare it to switching from aluminum to carbon arrows on my bow. I have not been able to match the efficiency of this setup using theragold.

Q


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## josephlys (May 4, 2010)

Thats a pretty good improvement in speed.


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## ZDP-189 (Mar 14, 2010)

landus94 said:


> Uuu, I see lenghty articles about physics and ballistics. Really interesting and useful. Thank you for helping me. Now I see that slingshoting is not as easy as I thought
> 
> 
> 
> ...


Landus94, I am glad you like my blog. I have a tendency to give the impression that lots of detailed research is essential. That's not the case. Slingshots are one of the simplest of target shooting sports and generations of school kids have shot successfully with no more that what's found in the home and garden. You can get a lot out of the sport with pure trial and error.

The blog does have its uses, though. When I got back into slingshots, I found the learning curve slow. I lacked the exprience to improve and I couldn't find hardly any of the answers to the questions I had. Indeed, it seemed like a lot of expert opinions were diametrically opposed. Debate raged between tube zealots and flatband fanatics, not to mention the chain gang. Worse still, different people had very different results with what appeared to be the same bandsets. So I started running my own tests and applied what I remembered of high school physics and what little literature was applicable. My shop jotter swelled and PC swelled with data, ideas and sketches. Some ideas were certain to be erroneous, misunderstandings or innovative dead ends. Others answered often asked fundamental questions. Still others were so obscure as to lack merit in the forum proper. But no person should work in a bubble and so I published it in a blog to throw it open to the talent and experience of the forum. I've enjoyed vigorous, informed debate, often going down in a furnace blast of flames







so take none of my writings as gospel. I am a long way off a comprehensive definitive understanding and therein is the joy of learning.

That said, there's enough in there to raise a newcomer to someone who is moderately knowledgable, to challenge the expert to rethink some aspect, or inspire creative juices when the well runs temporarily dry and stagnant.

Above all, I wish to foster a deliberate approach to slingshot and bandset design. When one comes to understand the science involved even conflicting experiences related on the forums start to make sense. Eventually one gets to the point where one can plan to get a certain set of characteristics and shooting specifications and design the bandset to deliver that. One will know where to where to compromise and the implications of that compromise.Take Qucifer's experience with Theraband Black for example. Black is about half the thickness of Gold and requires about twice the width to give the same draw weight. However, unladened it snaps back a bit faster so when shooting light loads, it can shoot faster, but the advantage diminishes with heavier shot. Also, bandlife typically drops 90% or more, especially tearing of bands at the pouch. So is Black noticeably faster than Gold? _It depends._ It depends on cut, draw and shot. If you reduce the taper to boost the duty life, or use a mismatched combination of variables, you could easily find Black under-performing Gold. The only way to predict this accurately is by understanding the underlying physics.

Likewise, the physics can tell you how to get more out of an existing bandset. Knowing that thin bands are best suited to light shot, you can focus on lightening the pouch and increasing taper. Knowing that a taper will further reduce the duty life, will give you some clues to how you need to innovate to improve this weak point. If nothing else it will avoid the disappointment of cuttingbands. following a recommended band formula only to find it doesn't work for you because of something not considered like one's arms being a different length to the designer's.

I wish I could close off the blog and compile it as one big tome, but it is far from complete. There are variables like temperature effects, effect of taper and velocity curves for different band thicknesses yet to be tested and published. If there is something important that I have missed, please drop me a PM. Likewise, if you wish to add any idea or throw a log on my pyre, please jump in with a blog comment.


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## landus94 (Jan 17, 2011)

I see you are really addicted to slingshot







Your job is really needed. So as I see, knowledge and all of the teoretical stuff is important but experimenting is important too! I won't stop searching the best bandset for me. I guess satisfaction of reaching the target after few disasters is amazing.

Thanks for everything. I'll think about what I'd like to see on your blog. Greetings!


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## josephlys (May 4, 2010)

ZDP you have a great blog, very very helpful. Also its an enjoying read. Thank you for the hard work and time involved, much appreciated


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