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Thera Band and Tube Resistance & Elongation Chart


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#21 Formidonis Noctu

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Posted 03 May 2011 - 03:58 PM

Ive come to the right forum, this along with so many other posts and articles here have been of tremendous help.
Thank you everyone

#22 Hugh Neverknow

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Posted 08 June 2011 - 01:26 PM

Would I be right or wrong to think that the amount of force required to stretch a length of latex is not a measure of the speed it sends a projectile?

For instance, would a set of bands made of green Theraband, that requires the same force to stretch as a set made of gold theraband (the width of the gold cut to match the force of the green) send a projectile of the same weight at the same velocity. I think but have no evidence yet that the red would be more powerful. And for the same reason that flat is better than tube or solid, the thinner the profile the quicker it can dissipate heat and return to its un-stretched form.

The ultimate aim is to have the highest velocity for the lowest stretching force. I realize other factors come into play such as durability, pouch size, %age of stretch and no doubt a lot of others. But all other factors being equal I think the thinner the band the better

I now await to be told I am wrong and why, while I wait for my chrony to arrive so i can settle this for myself. It is almost like science!

#23 Hit and run

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Posted 11 June 2011 - 02:27 AM

Would I be right or wrong to think that the amount of force required to stretch a length of latex is not a measure of the speed it sends a projectile?

For instance, would a set of bands made of green Theraband, that requires the same force to stretch as a set made of gold theraband (the width of the gold cut to match the force of the green) send a projectile of the same weight at the same velocity. I think but have no evidence yet that the red would be more powerful. And for the same reason that flat is better than tube or solid, the thinner the profile the quicker it can dissipate heat and return to its un-stretched form.

The ultimate aim is to have the highest velocity for the lowest stretching force. I realize other factors come into play such as durability, pouch size, %age of stretch and no doubt a lot of others. But all other factors being equal I think the thinner the band the better

I now await to be told I am wrong and why, while I wait for my chrony to arrive so i can settle this for myself. It is almost like science!


Generally, for two bands with the same mass the one with the highest surface area will contract the fastest. (http://www.melchiorm...info_power.html subsection band shape)
The big disadvantage of the thinner bands is that you need a broader band to propel the same mass, (Green vs. Gold around 2.5x the width) and they break faster.

#24 Hugh Neverknow

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Posted 16 June 2011 - 11:09 AM

That makes sense - I was trying to think of why the thinner band would be faster but surface area would be the reason for the transfer of heat?

Of course the wear factor, wind resistance, general practicality will be issues but this was bugging me thank you for your clarification

Would I be right or wrong to think that the amount of force required to stretch a length of latex is not a measure of the speed it sends a projectile?

For instance, would a set of bands made of green Theraband, that requires the same force to stretch as a set made of gold theraband (the width of the gold cut to match the force of the green) send a projectile of the same weight at the same velocity. I think but have no evidence yet that the red would be more powerful. And for the same reason that flat is better than tube or solid, the thinner the profile the quicker it can dissipate heat and return to its un-stretched form.

The ultimate aim is to have the highest velocity for the lowest stretching force. I realize other factors come into play such as durability, pouch size, %age of stretch and no doubt a lot of others. But all other factors being equal I think the thinner the band the better

I now await to be told I am wrong and why, while I wait for my chrony to arrive so i can settle this for myself. It is almost like science!


Generally, for two bands with the same mass the one with the highest surface area will contract the fastest. (http://www.melchiorm...info_power.html subsection band shape)
The big disadvantage of the thinner bands is that you need a broader band to propel the same mass, (Green vs. Gold around 2.5x the width) and they break faster.



#25 slingshotwizard

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Posted 01 November 2011 - 11:54 AM

Thanks i was having trouble gauging the strength of my bands

#26 Warhammer1

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Posted 07 March 2012 - 11:37 PM

I have speargun tubing 1/4 inside diameter, 1/8 wall thickness. This stuff is sic. I am pulling my arms out of their sockets. NO idea what pull it is, but color is red if that makes a diff. I think its about 50lbs at 300% or something like that.

#27 breakerboy2000

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Posted 15 March 2012 - 08:04 PM

same, I use 9mm black spear gun rubber tubing that just slides over my sling frame, its very strong, I was wondering if anyone has used this aswell and could tell me how it compares with theraband? and other flat bands? I am shooting 11mm lead balls with it and they are great.

#28 RogueWaveHorizon

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Posted 12 November 2012 - 01:35 PM

Thanks that was great.

#29 Guest_OldSpookASA_*

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Posted 13 November 2012 - 05:12 PM


I presume the elongation refers to full 6" width by 12" elongated to 24" lengthwise, but maybe it refers to full length.


From this document: http://www.thera-ban...tion_Manual.pdf

It suggests that the measurement is a 2 foot full width section stretched to 4 feet for 100% and stretched to 6 feet for 200% elongation. One problem with this notation is that it is not correct. The section is 100% it's length to start with. When it is stretched to 4 feet it is at 200% elongation but that is a moot point.

I'm interested in this information and would really appreciate any data anyone can provide about measurements made by users of this forum for elongations greater than those documented. I am working on a spread sheet. I intend for it to be able to estimate projectile velocity given the various parameters of draw length, band design, band material, projectile weight. It will support Clay, Glass, Steel, Brass, and Lead spherical projectiles. The idea is to give the band designers a true spread sheet which will let them play with various scenarios.

So if you have a spare section of full width Theraband two feet long of any color. Simpy attach a string to each end and pick up various weights off the floor. Document the length to which that bit of band stretched when each weight was off the floor. I'll do the math and share the results here when I have enough data to make reading it worth you while. For this to be valid, you need two feet of band between the knots on your strings.

Thanks

#30 Guest_OldSpookASA_*

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Posted 13 November 2012 - 05:22 PM

I was looking at the relationship between thickness and the amount of traction force required for elongation. I expected to see a nice relationship with yellow at one extreme, gold at the other and the others lying proportionally along the curve.

That's not what I found.

Yellow: 967 lbs/inch thickness @250% elongation
Red: 875 lbs/inch thickness @250% elongation
Green: 960 lbs/inch thickness @250% elongation
Blue: 1,108 lbs/inch thickness @250% elongation
Black: 1,173 lbs/inch thickness @250% elongation
Silver: 1,150 lbs/inch thickness @250% elongation
Gold: 1,604 lbs/inch thickness @250% elongation

Source: Force numbers from Aaron's table; thickness from Thera-band.

It raises the possibility that either the inputs are wrong or Thera-band are using different compounds for different colours.


I think the data in the charts is such that rounding errors could cause this kind of skew. The information we have is only accurate to two decimal places in inches. We don't know if the actual measurements shown in the charts here:
http://www.thera-ban...tion_Manual.pdf
were measured in Kg or Pounds as there are two charts presented one accurate to tenths of a pound and the other to tenths of a Kg. That data is just not accurate enough to extrapolate to four or five digits.

#31 Guest_OldSpookASA_*

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Posted 16 November 2012 - 04:55 PM

Ho! Ho! I found some data for tubing: http://ptjournal.apt...6a-f37de1d0ebc4

#32 hautamak

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Posted 22 June 2013 - 04:52 PM

I went shopping for thera-band at Amazon. There was listed there bands and tubes. In all these colors listed. And they were also in either latex rubber or non-latex rubber. Do the two, i.e., latex vs non-latex pull with the same resistence ?
Thank you very much for these charts by the way.


I have some cheap non latex stuff and it elongates to 200% and then stops, crappy stuff, but I could be wrong...



#33 hautamak

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Posted 22 June 2013 - 04:55 PM

same, I use 9mm black spear gun rubber tubing that just slides over my sling frame, its very strong, I was wondering if anyone has used this aswell and could tell me how it compares with theraband? and other flat bands? I am shooting 11mm lead balls with it and they are great.

why my speargun have 18mm rubbers ? :D  my bungee have 9mm band, but I don't have it so much for trying it and 18mm is way too strong (over 80kg pullweight)



#34 Jolli4688

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Posted 10 September 2013 - 04:59 AM

Ok..... using the above Chart

 

1. I plan on using Theraband blue flats

2. Having a approx draw length of 28" (fist to chin)

 

for 11.1lb of pull i want a effect band length of 7" from fork to pouch right? =/

 

This would only be a single band set up too wont it? would multiple bands double the effects or only partially increase the draw weight?



#35 Arturito

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Posted 11 September 2013 - 08:27 AM

Unfortunately these charts are plotted to 250%, does someone has measured TBG to 500% elongation ?, would be useful to retrofit my band simulator ...

 

Cheers

Arturo



#36 zwillie

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Posted 25 September 2013 - 02:38 PM

Hi Arturo,

you know that I prefere Megarubber instead of Danking or Thera here is a chart for those bands up to 400%.

 

http://www.emc-vega....hnik/Megarubber

 

 

Cheers

Zwillie


Edited by zwillie, 25 September 2013 - 02:39 PM.


#37 kwinpr

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Posted 25 September 2014 - 03:00 PM

This thread answers a lot of the TB questions I had!



#38 RedloeseBob

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Posted 14 August 2015 - 04:17 AM

Would I be right or wrong to think that the amount of force required to stretch a length of latex is not a measure of the speed it sends a projectile?

For instance, would a set of bands made of green Theraband, that requires the same force to stretch as a set made of gold theraband (the width of the gold cut to match the force of the green) send a projectile of the same weight at the same velocity. I think but have no evidence yet that the red would be more powerful. And for the same reason that flat is better than tube or solid, the thinner the profile the quicker it can dissipate heat and return to its un-stretched form.

The ultimate aim is to have the highest velocity for the lowest stretching force. I realize other factors come into play such as durability, pouch size, %age of stretch and no doubt a lot of others. But all other factors being equal I think the thinner the band the better

I now await to be told I am wrong and why, while I wait for my chrony to arrive so i can settle this for myself. It is almost like science!

Your acctually right, just because you got a hard draw doesnt mean that you will get equal power.

 

Generally it depends on how thin the rubber are and how long your draw is and also how quick you shoot.

 

If you hold the rubber stretched enough time it will cool down the heat and decrease the power of your shot.

 

So the key for power without tapering your band is to shoot with full butterfly stance with thin rubber and to shoot active whichs means you shoot instant after you just pulled out the rubber. 

 

And also the weight of the projectile is a great factor so if you want to come up to 100+ joules you probably have to have enough drawweight to handle the weight of a 20mm steel (+) so the rubber can retract with it's originally speed and give you that speed that you need.



#39 Darin Kel J

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Posted 12 November 2015 - 01:09 AM

Here are some specs that they offer:
Tubes
Tan .062 ID x .031 wall
Yellow .200 ID x .045 wall
Red .200 ID x .057 wall
Green .200 ID x .069 wall
Blue .200 ID x .085 wall
Black .200 ID x .098 wall
Silver .200 ID x .125 wall

Bands
Tan/Extra Thin
Yellow/Thin
Red/Medium
Green/Heavy
Blue/Extra Heavy
Black/Spcl Heavy
Silver /Spr Heavy
Gold/Max

I've never seen blue, silver or gold. Where do you get thees? I've seen different sized black bands, but not the blue, silver or gold



#40 Darin Kel J

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Posted 12 November 2015 - 01:30 AM

same, I use 9mm black spear gun rubber tubing that just slides over my sling frame, its very strong, I was wondering if anyone has used this aswell and could tell me how it compares with theraband? and other flat bands? I am shooting 11mm lead balls with it and they are great.

I just bought some 2 weeks ago just to see how they were because it's had where I am to find a lot of choices of bands though the Trumarks are good but I don't always see those in the stores so I wanted to make my own.  I haven't used them yet though. So they are good?






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