# Speargun rubber arrived - medieval crossbow rocks!



## JoergS

Ordered some speargun rubber.

Got 16, 18 and 20 mm thickness, a meter each.

The stuff is beastly! I decided to test the "weakest" one first. 6,5mm walls, compared to 3mm walls on the already tough Thera Tube silver. Here you see TB black, silver and the 16mm speargun rubber in comparison.


















Did a bandset for the medieval crossbow. The center hole is too small and the rubber is too tough for the knot in hole method, so I attached the rubber to the outside. Works fine.


















Draw weight of this exceeds the 40 kg my scales can measure. I estimate it at 45 kg (about 100 lbs).

I reinforced the nut and tickler with steel because I did not trust the wood on wood method for this off the scale power. It holds fine.

It is surprisingly easy to cock the crossbow, the stirrup method rocks. Ancient weapon makers clearly knew their stuff.

It shoots absolutely frighteningly fast. My most powerful sling-x-bow for sure.

But there is room for improvement - see the 18 and 20 mm beasts in comparison... stay tuned.










Jörg


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## NaturalFork

How the heck does that leather not break with that large hole in the center?


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## NightKnight

i cannot wait to see what kind of numbers you get out of it with the different rubbers!


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## Bill Hays

It should be interesting to see what you can get with that.
I know that stuff will propel an arrow under water really well... it just seems logical that it'll shoot something pretty heavy very fast in the open air.


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## JoergS

NaturalFork said:


> How the heck does that leather not break with that large hole in the center?


I was very lucky with that leather. It is fairly thin yet virtually unbreakable, I NEVER had a pouch made from it ripping.

The ten millimeter center hole is important, otherwise the pouch may slipp off the bullet.


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## huey224

nice work joerg!
yeah, speargun rubber is very tough im sure it will last quite long!


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## Nico

How fast does the speargun tube shoot those 19 mm lead balls Joerg?


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## Lizard_King

So where is a video ,, Wanna see it shot with a new power bands ..
Maybe some destraction video with that crossbow ?


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## strikewzen

hahhaha i am your biggest fan watched every one of your vids many times over

cannot get enough now have to log onto slingshot forum to see the prototypes lol

seriously be careful man sometimes you're like a stuntman with the machetes and circular sawblades


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## JoergS

Yes, sometimes I feel like the Evel Knievel of slingshots.


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## PandaMan

JoergS said:


> Yes, sometimes I feel like the Evel Knievel of slingshots.


That's because you are! Look at that rubber, man!
Only difference is, you haven't broken any bones with your slingshots!


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## kobe23

Joerg is trying to make this weapon into the army, or maybe Afghanistan, the anti-car-bomb weapon =D


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## JoergS

It throws the 22mm (.87") lead ball (64,2 gramms = 1027 gr) at 46 m/s, 150 fps. Not bad for a 70 cm (27") draw. It will be interesting to see how the thicker bands perform.


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## A+ Slingshots

That is exciting!!! Very cool!!!!


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## mckee

i got no chance of drawing that lol are u doing a vid?


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## JoergS

Here is a little video that shows the weapon rigged up with the new speargun stuff.


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## mckee

good vid joerg


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## Dayhiker

That's a baaaad boy!


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## xtj7

At least you don't have to hide that from children. Everyone capable of actually drawing that beast is old enough to handle it anyways









By the way: did you get my private message on Youtube?


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## Beanflip

Bravo Joerg. Now that is entertainment!


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## JoergS

Have made a bandset with the strongest 20 mm rubber today. I did use paracord even for the constriction knot, not the thin 20 kg string I normally employ, and tightened the knots in the vise, with one leg against the bench and the other string end wrapped around a pole so I could pull with both hands.

I also used doubled up leather for the pouch.

Draw weight is 90 kg (198 lbs). I can still cock the weapon! The stirrup method is just the best.

Here you can see some pics, in comparison with the "flimsy" Thera Band Black and the "mediocre" 16 mm spear gun rubber.

Band weights (total with pouch):

TB black 25 gramm (400 gr)
16 mm speargun 65 gramm (1040 gr)
20 mm speargun 102 gramm (1632 gr)





































Will do some shooting later on!

Jörg


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## JoergS

OK, too much. Reinforcement is needed.










Broke when I had it pulled out completely, hit me in the right side of my torso... but nothing serious.

I am clearly leavin the toy zone here.

Jörg


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## Tobse

oh ****! i think about this problem as i see this big Rubbertubes!
I´m happy, it looks to me you still alive!


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## JoergS

Bruised, battered and a bit frustrated, but alive and kicking!


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## Rapier

PandaMan said:


> Yes, sometimes I feel like the Evel Knievel of slingshots.


That's because you are! Look at that rubber, man!
Only difference is, you haven't broken any bones with your slingshots!








[/quote]

YET!


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## Rapier

Wow Joerg. That beats the medieval boys hands down. I'm betting they'd crap their daks!


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## JoergS

Everything is repaired, with reinforced parts. But for now, the 20 mm tubes get a rest.


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## NoSugarRob

your a proper nutter Mr J


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## NightKnight

Sorry you got hurt, but glad you found a structural deficiency before it hit you in the face or something!


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## bikermikearchery

I realy want to see the big stuff in action.


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## JoergS

I am still struggling with the band attachment.

The thick tubes have so much draw force that the conventional methods all fail. Knot in tube slips out. Constriction knot does not help. I am now trying a double constriction knot loop with additional rubber band attachment. This may or may not work.

Next problem is the nut, which is steel reinforced, but still it is mostly wood. I may have to replace both nut and tickler with massive steel parts.

A 200 lbs balester (ball shooting crossbow) is worth the effort, though. This will be a mighty weapon only strong men can draw out and load.


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## PandaMan

This will be awesome!


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## bootneck

I think a destruction vid is needed on the 20 mm stuff, can you get sheep and pigs heads were you are? or cows heads? since there not flexable i bet it'l make a better video than trying to shoot through thick pig skin, and we know it will go through meat fine so how about a head?


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## colt

this is really interesting to me. you are coming up on some really good power! very cool


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## bikermikearchery

. This is the most intriguing crossbow designs yet. I hope you will do some more shooting videos with this design. I am interested in how the short draw with pre-stressed bands compares to the longer draw bands on your other designs


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## Simon Van den Broeck

can you shoot arrows with this one you think ? can i have some help at that i want to make on of these to the stock is allready finished


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## PebbleShooter

Have you thought about using hose clamps, heavy duty zip ties or something like that?

Only problem i see there is it cutting into the rubber with use which you don't want.


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## Simon Van den Broeck

JoergS said:


> I am still struggling with the band attachment.
> 
> The thick tubes have so much draw force that the conventional methods all fail. Knot in tube slips out. Constriction knot does not help. I am now trying a double constriction knot loop with additional rubber band attachment. This may or may not work.
> 
> Next problem is the nut, which is steel reinforced, but still it is mostly wood. I may have to replace both nut and tickler with massive steel parts.
> 
> A 200 lbs balester (ball shooting crossbow) is worth the effort, though. This will be a mighty weapon only strong men can draw out and load.


hye joerg , i wazs wondering if it is so hard to cock maybe you can use a goatsfoot?


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## cheese

x







+







+







^2-







=me!


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## mattardel

That is absolutely frightening! I LOVE IT!


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## lightleak

Wow, very impressive. I guess its time to move ahead and instead of the safety goggles get a nice full face helmet..

Was thinking about something like this:










Best regards!









l.


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## 4950cycle

I doubt he is still doing this stuff. He is probably so busy making those Rambone slingshots. They are selling out as fast as they can send them here in the states.


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