# Figure 8's



## Wooky (Aug 13, 2013)

Hello everyone, I was wondering, are any of you still shooting the Figure 8's? I have always used board cuts for my slings, just something about wood, however recently my wants have changed. I have ordered a few of these figure 8's to see what I can come up with for a set up.

If you guys dont mind please post your band/tube setup for figure 8's, personally I was hoping to be able to 3/8" steel out it.

Thanks in advance!!

Wook


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## Resigned User (Jul 4, 2015)

Here is mine
I follow suggestions of Lunasling and the video of Eric


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## Wooky (Aug 13, 2013)

Nice setup!! Thanks for the info., Widget!! I ran a search on Google and really only found a handful of ways of attaching bands/tubes these figure 8's? So far what I have seen folks using bands I am not a fan, tubes should be fairly simple.


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## JTslinger (Jan 26, 2015)

I have a Tab&Tap from from Eric at Metrograde Goods, currently banded with tubes for shooting BBs. It can easily handle larger tubes for 3/8" steel.


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## Resigned User (Jul 4, 2015)

Here a closer look


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## Byudzai (Aug 31, 2013)




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## JTslinger (Jan 26, 2015)

Byudzai's figure 8 frames shoot very well. Love that tune attachment method as well.


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## Wooky (Aug 13, 2013)

Thanks fellas for the info,. although that last tube setup looks a bit weak as the holes are close together as well as the tube slots? Maybe for a BB shooter it be alright....


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## Byudzai (Aug 31, 2013)

Wooky said:


> Thanks fellas for the info,. although that last tube setup looks a bit weak as the holes are close together as well as the tube slots? Maybe for a BB shooter it be alright....


if you have a 200lb pull on your tubes you might start to worry. until then the 1/2" aluminum is plenty strong around the holes.


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## Viper010 (Apr 21, 2012)

A bit weak? What size steel are you planning to launch, exactly? 3/8" or 3" 1/8?¿?


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## Wooky (Aug 13, 2013)

Viper010 said:


> A bit weak? What size steel are you planning to launch, exactly? 3/8" or 3" 1/8?¿?


I am not exacty sure where you see the 1/2" of aluminum? From what I can see, that figure 8 looks like its about .375" or a touch over in dia.. It looks like you have at least 2 - 1/8" - 3/16" holes inline with each other, per side, as well as on end of the holes has a slot cut into it. So according to what I see this is what I come up with: If the figure 8 is lets say .375" in dia. and the holes you have placed are .125" in dia that leaves you with about .250" material left for "strength" now thats an over all dimension so you will have to divide that by two and that will leave you with .125" around those hole areas. @viper010 Not trying to upset anyone, just my observation, if you can explain something I dont see, please feel free to comment, I would love to hear.


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## Viper010 (Apr 21, 2012)

#DISCLAIMER#
I'm not an engineer. What I stated here, is merely my uneducated guess. If somebody who actually knows what they're talking about could correct me if I'm wrong, PLEASE DO!

Lol well...Like I said... I'm not a structural engineer, so I don't know if what I'm about to write up counts as an explanation per sé... It's more of an "uneducated educated guesstimate". But let me give it a whirl...

If I recall right, from what little my brother and my highschool physics teacher explained to me about climbing equipment and shock loads.

In its original form, with the proper lines attached, I think my brother told me that these 8s, and all his other carabiners and stuff are rated to take 500kg (+-1100lbs) from a 10mtr (33ft) drop. I'm not quite positive I got my numbers right, but I think he said something about 10.000kg (22.000lbs) shockload...

At any rate, IF you have the real deal, a piece of genuine certified climbing gear and not just a lump of aluminum in the shape of.... These things are so strong, it's ridiculous. On that slingshot byudzai made, you could tie a bandset worthy of Joerg Sprave lashed ott without any worry at all.

There just is NO WAY you could ever bend or otherwise damage that thing with tubes that actually fit through the holes.

@Wooky... I value my eyesight and front teeth just as much as the next man, so I understand your worry. I just don't feel as worried as you do about this particular slingshot.

@metro n Byudzai... Did you get a spec sheet n test report with those figure 8s? I'd love to see the accurate weight load and shock load numbers.


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## Wooky (Aug 13, 2013)

I appreciate your (view/explanation) Viper010 and yes I have the real deal as far as descenders go, this particular one is 25KN.

From what I understand tying flat bands on this figure 8 would be an unfair example, for one, you would be tying the flat bands on a solid piece of .375", agreed that even the bands that Mr. Sprave uses it would hold!

Now let's talk about the shear strength of said .375" rod after taking away .125" and then cutting a slot half way thru the hole? Since the stock is .375 and round, I have already wrote what material would be left, .125" per side. Now that we know that don't forget that it is round so this means that not only do you have .125" per side of material left now count the radious and subtract from the initial .375".

Once the piece has been modified all those shear strength/shock loads go out the window as you have taken material away from its original shape.

I think the tube setup above would be fine with a BB shooting setup.

So far, the safest and nicest setup I have seen is the one that Metro Grade made using gypsy tabs. At least for me and at least for anything heavier than 3/8 steel.


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## Chuck Daehler (Mar 17, 2015)

Wookie, nice idea!!! I've not seen this on a figure 8 before. Sure is a nice way to sort of extend the fork a bit to give the flat bands and pouch a little more breathing room to flow through.

and Byud, Congrats on SSOTM too. Keep 'em comin'.


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## Viper010 (Apr 21, 2012)

Hmmmmm... Do these things come in different ratings? I distinctly remember my brother mentioning a 10.000kg Max shockload (100KN)

Or was it, that in order to receive certification for 25KN, it needs to be tested at 100KN (300% redundancy)? Now I'm a bit confuzzled I must admit.... 
Would love it if an actual structural engineer could chime in with some explanations in layman's terms....

I do agree that all shockload ratings and calculations go out the window as soon as you start changing the shape, and especially when removing material. (this means, that if you have sawed half way through something, it's not necessarily half as strong as before you started sawing anymore but could be much much weaker)

Still, in my LAYMAN'S OPINION, I think it would be impossible to bend or otherwise damage Byudzais drilled and cut figure8 by attaching tubes that you can actually get squeezed through the drilled holes. I bet you can band that sucker up, stretch the tubes till they break, do that 10.000 times and still notice no deformation of the frame what so ever.

However, banding it up with the heaviest tubes it can take, and then getting a fork hit from a heavy steel or lead ball.... Different story entirely! I'm pretty sure that would bend the tip, which you MIGHT be able to safely bend back ONCE. Operative words being MIGHT JUST and ONLY ONCE. But do that repeatedly, and I guarantee you that it WILL BREAK AT SOME POINT!

So yeah... I think it's a perfectly safe design, safe to use with any tubes you can fit to it. But if you take a heavy fork hit, better to discard it and make a new one.

Again, merely my personal uneducated opinion.


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## Metropolicity (Aug 22, 2013)

Even poor alloyed aluminum will take a lot of PSI before it bends or fatigues, a thin 3mm, 1/8 section can easily hold 20-25 lbs. The cross section of the Fig 9's is nearly 13mm and these are usually die formed which means the aluminum is compressed further (binding the particles and crystal structure closer for a denser alloy).

The cheaper versions are die formed, rarely will you find a CNC cut one (if you do, you aren't paying $15 for one).


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## Wooky (Aug 13, 2013)

Thats an acceptable answer, thanks for the info., Metropolicity!!

20-25lbs sounds a lot different than.....the large figures posted above. The numbers Metropolicity posted makes sense, I feel a lil better about what direction to go.


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## Byudzai (Aug 31, 2013)

Now I'm curious to try the experiment. I think I'll make one of these, clamp it to a beam, run paracord through the holes, and suspend my 200lbs from it. If that holds, I'll try to snap the tips off by bouncing on it. In my imagination it'll hold just fine, but if not then... it'll be better not to use 200lb elastics after all ;-)


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## Metropolicity (Aug 22, 2013)

Byudzai said:


> Now I'm curious to try the experiment. I think I'll make one of these, clamp it to a beam, run paracord through the holes, and suspend my 200lbs from it. If that holds, I'll try to snap the tips off by bouncing on it. In my imagination it'll hold just fine, but if not then... it'll be better not to use 200lb elastics after all ;-)


That's one heck of a hand slap


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## Wooky (Aug 13, 2013)

Byudzai said:


> Now I'm curious to try the experiment. I think I'll make one of these, clamp it to a beam, run paracord through the holes, and suspend my 200lbs from it. If that holds, I'll try to snap the tips off by bouncing on it. In my imagination it'll hold just fine, but if not then... it'll be better not to use 200lb elastics after all ;-)


@Byudzai, love the sarcasim!! I cant wait to hear the outcome!! I am sure you will post if you are right. Must have been a sensitive subject? Over a safety question?


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## Byudzai (Aug 31, 2013)

Wooky said:


> @Byudzai, love the sarcasim!! I cant wait to hear the outcome!! I am sure you will post if you are right. Must have been a sensitive subject? Over a safety question?


I guess man. It's kinda like dissing the design of a car seatbelt bc it couldn't keep a space shuttle from launching. Those tips will hold the toughest tubes with the longest draw you can throw at them -- BUT I do acknowledge that I'm just talking until I can prove it. So I unsarcastically invite the motivation to test them out.


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## Wooky (Aug 13, 2013)

Byudzai said:


> Wooky said:
> 
> 
> > @Byudzai, love the sarcasim!! I cant wait to hear the outcome!! I am sure you will post if you are right. Must have been a sensitive subject? Over a safety question?
> ...


Actually, I would also disagree with the seat belt example: seat belts have been tested and as long as they havent been "modified", no need to for any further testing. Unless, you want to cut 3/4 of the way thru the seat belt and see if it will still hold at high speed? Or shall I just take your word for it?

I guess there are a few of you that just expect people to take your word for it? Why is that? This was merley a safety question, I would like to keep my eyes as well as any other facial extremities as they are. Is this not a forum that folks can ask questions and receive answer without any sarcasm or holier than thou attitude? And nothing to back up the answer, just your word. That may be fine for some.....


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