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Discussion Starter · #1 ·
I would use Kintex Silver - very fast fitness rubber bands.
It propels 8mm steel well over 130m/s with some tapering.

I suppose that I will just have to adapt to the weight of 12mm steel
and use about 3,2x the bands for the 8mm steel setup and I should achieve the same velocities, right?
(7,1g vs 2,2g)

Yes... the draw weight will be hefty. But I'm training my bizeps and finger grip. So in spring I should be able to hit something with it, at least at shorter range.

For pure destruction fun... 馃檲
 

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I hope you succeed - but you have your work cut out for you.

I have a couple of "Dreadnought" starships - they're banded with a full strip of Theraband Gold (-20mm).
The draw is 1220mm, of which 914mm is the active draw length (when the bands are actually stretching).
At full draw the draw weight is over 25KG
I experimented with different weights of projectile, the heavier the projectile the higher the energy.
It shoots 25.4mm steel balls, these weigh 58g (895gn) and travel at 41m/s for a "muzzle energy" of 35.96 ftlbs.
It takes a lot of effort to shoot it.

Please keep us informed - maybe those Kintex bands are fundamentally different to TBG.
 

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If you haven't already go to the Power Rangers Forum for ideas on how to get big power.

 

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I would use Kintex Silver - very fast fitness rubber bands.
It propels 8mm steel well over 130m/s with some tapering.

I suppose that I will just have to adapt to the weight of 12mm steel
and use about 3,2x the bands for the 8mm steel setup and I should achieve the same velocities, right?
(7,1g vs 2,2g)

Yes... the draw weight will be hefty. But I'm training my bizeps and finger grip. So in spring I should be able to hit something with it, at least at shorter range.

For pure destruction fun... 馃檲
This will be interesting. stay safe while shooting this bad boy.
 

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Discussion Starter · #7 · (Edited)
I hope you succeed - but you have your work cut out for you.

I have a couple of "Dreadnought" starships - they're banded with a full strip of Theraband Gold (-20mm).
The draw is 1220mm, of which 914mm is the active draw length (when the bands are actually stretching).
At full draw the draw weight is over 25KG
I experimented with different weights of projectile, the heavier the projectile the higher the energy.
It shoots 25.4mm steel balls, these weigh 58g (895gn) and travel at 41m/s for a "muzzle energy" of 35.96 ftlbs.
It takes a lot of effort to shoot it.

Please keep us informed - maybe those Kintex bands are fundamentally different to TBG.

If one wants higher speeds, it seems one needs other rubber. theraband gold isn't the fastest.
this was done 10 years back with blue theraband (thinner is better):


and modern slingshot rubber is super fast:


So in simple understanding, if I take those fast bands 7,1g / 2,2g = 3,22x, I should get about the same velocity.

If I make the bands with same taper ratio, as for 8mm with 130m/s just a little wider, with 3 layers I should be there.
Only problem is, that I atm haven't got a chrony.
And probably I won't take the very cheap China Chrony but rather from Caldwell. Next year I could chrony and keep you updated.

But I still will share some impressions of heavy impacts till the chroy is ready for use... (y)
 

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Discussion Starter · #10 · (Edited)
I did use the golden for 8mm. It's ok for having fun, but its not super speedy.
In Full Butterfly cut to 30-20 it was the fastest, of the taperings I tested.
currently I use 30-18. this is a bit more comfortable to aim. - I'm no Hulk yet.
it's just too thick for going really fast (I think its not faster than 360fps).
(I can guesstimate the velocities roughly because I have airguns for comparison. the weak co2 pistols are in that range).

Silver should be a lot faster - about 20-25m/s or so.
thats what I saw in tests on youtube and on an other page.
Of course I need more rubber area to get the same draw weight,
but this should bring me to the magical 430fps.
 

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Discussion Starter · #13 · (Edited)
130 m/s with 12mm steel should be within reach if you can stretch your full butterfly draw length to about 3.5 meters.
you mean with a single band?
If I'm not totally wrong, it's just a matter of pulling force, thin rubber and draw length. if the pull weight is ~3x with the same fast bands as for a 8mm 130m/s bandset (triple layers=3x pulling force) I don't see why the rubber shouldn't be able to contract just as fast as the single 8mm bandset would do.

If I would take a thicker band, I could agree with you, since thicker rubber would be slower.
To my understanding, there is no reason why the same rubber shouldn't be able to perform the same with the same weight/pull force ratio. but maybe I'm missing something.
 

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you mean with a single band?
it's just a matter of pulling force, thin rubber and draw length. if the pull weight is ~3x with the same fast bands as for a 8mm 130m/s bandset (triple layers=3x pulling force) I don't see why the rubber shouldn't be able to contract just as fast as the single 8mm bandset would do.
You have the pulling force for singles & doubles, and doubles will increase the speeds considerably. But triples might add 20 or 30 fps because they're 3x harder to draw... It's just not worth pulling a tendon to try and pull triples. Watch the doubles in my first set in the video. They easily pull over 400fps, but they were normal draw to my ear. Still... a hard pull, but doable.

 

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Discussion Starter · #15 ·
If the weight of the 12mm is 3,2x of the 8mm,
I would at least need triples of the 8mm bandset. (to get to the same draw weight).
In reality doubles could be in the near, I will compare then.
 

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you mean with a single band?
If I'm not totally wrong, it's just a matter of pulling force, thin rubber and draw length. if the pull weight is ~3x with the same fast bands as for a 8mm 130m/s bandset (triple layers=3x pulling force) I don't see why the rubber shouldn't be able to contract just as fast as the single 8mm bandset would do.

If I would take a thicker band, I could agree with you, since thicker rubber would be slower.
To my understanding, there is no reason why the same rubber shouldn't be able to perform the same with the same weight/pull force ratio. but maybe I'm missing something.

Retraction rate is what limits speed. And for this thinner latex is faster. This is the reason double bands are faster than singles, i.e. double 0.4 will be a bit faster than a single 0.8 thick band.

The heavy ammo you are trying to move compounds the problem. Thinner bands don't have the power to accelerate heavy ammo (obviously). The way around this is to extend draw lengths- this is the magic of butterfly and starships. The longer draw lengths give the ammo more time to push on the ball. While the thin bands have a hard time moving the heavy ammo, give them enough time to push on the ball and they will eventually get it up to speed.

Thus my joking post about expanding your butterfly draw to ~3.5 meters to get 12mm steel up over 130 m/s. If one could really draw that far, the thinner elastics with their faster retraction rates would steal the show and dominate.
 

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Discussion Starter · #17 · (Edited)
Retraction rate is what limits speed. And for this thinner latex is faster. This is the reason double bands are faster than singles, i.e. double 0.4 will be a bit faster than a single 0.8 thick band.

The heavy ammo you are trying to move compounds the problem. Thinner bands don't have the power to accelerate heavy ammo (obviously). The way around this is to extend draw lengths- this is the magic of butterfly and starships. The longer draw lengths give the ammo more time to push on the ball. While the thin bands have a hard time moving the heavy ammo, give them enough time to push on the ball and they will eventually get it up to speed.

Thus my joking post about expanding your butterfly draw to ~3.5 meters to get 12mm steel up over 130 m/s. If one could really draw that far, the thinner elastics with their faster retraction rates would steal the show and dominate.
but thats why I use 3x the same (fast) bands. so I have 3x pulling force(!) of a single 8mm band.
I could have the same pulling force with a much thicker single (12mm) band what would limit the retraction rate.

example:

1 thick band with 15kg pulling force but max. retraction rate is only 110m/s. (bad)

3x thin bands with 5kg pulling force each and 130m/s max. retraction rate. = 15kg pulling force. (good bandset)

only drawback is that the thinner bands won't last as long and are more expensive. but will be well worth the expense since the energy increase is 30%

If I would use a thin single, fast bandset but with less pulling weight, your point would be true, for sure.
and that's why i will go for thin, fast triples.

Like this guy:

If I'm still not getting 430fps, I have to use wider band cuts or an extra layer of band (4x 8mm band).
Or... simply try different latex.
 

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but thats why I use 3x the same (fast) bands. so I have 3x pulling force(!) of a single 8mm band.
I could have the same pulling force with a much thicker single (12mm) band what would limit the retraction rate.

example:

1 thick band with 15kg pulling force but max. retraction rate is only 110m/s. (bad)

3x thin bands with 5kg pulling force each and 130m/s max. retraction rate. = 15kg pulling force. (good bandset)

only drawback is that the thinner bands won't last as long and are more expensive. but will be well worth the expense since the energy increase is 30%

If I would use a thin single, fast bandset but with less pulling weight, your point would be true, for sure.
and that's why i will go for thin, fast triples.

Like this guy:

If I'm still not getting 430fps, I have to use wider band cuts or an extra layer of band (4x 8mm band).
Or... simply try different latex.
That is an old video, he has a whole set, look thru his channel. For the first triple band set that you make, add an extra 30% on your band length. It's a hard pull for anyone. This way you can judge how much that you will be able to shorten it at full draw and not waste a band set because you can't pull it back completely. It's not the weight of the bands that makes it tough, it's trying to hold onto the pouch with a couple of fingers that's the weak point.
 
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