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BigShot Slingshot

Unread postPosted: Mon Aug 17, 2009 2:08 pm
Author: boyntonstu
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Some details:

The temporary trigger is a pair of pliers ground to fit a marble in the pouch.

I had to a length just to full draw a pair of silver Thera Band rubbers.

I made the pulleys out of static caster wheels held and spinning against a bench grinder wheel.

A triangle that flips down to hold the right angle is definitely needed.

Perhaps another automatic hold-back.

I may have to go to a multi-pulley system to draw this giant.

I added a few photos to show some details.

The pulley draw really helps and I can tie it off to prevent swing up.



BoyntonStu

Unread postPosted: Mon Aug 17, 2009 2:10 pm
Author: spudtyrrant
a little overboard on the string, but you made it work apparently.
so.....hows performance.

Unread postPosted: Mon Aug 17, 2009 2:17 pm
Author: Gippeto
I have to ask "Why" did you build it like this??

You have additional losses due to friction, I can't see performance being as good as a "standard" type slingshot.

What is it you're trying to achieve with this design? :?

Unread postPosted: Mon Aug 17, 2009 2:20 pm
Author: boyntonstu
spudtyrrant wrote:a little overboard on the string, but you made it work apparently.
so.....hows performance.


The string is the perfect length except for trim.

Notice the pouch is at the end of the shot.

You start with the pouch held in the pliers and the board vertical.

You draw by pulling it own 90*.

Performance?

You would not want to stand in front of it.

BoyntonStu

Unread postPosted: Mon Aug 17, 2009 2:23 pm
Author: boyntonstu
Gippeto wrote:I have to ask "Why" did you build it like this??

You have additional losses due to friction, I can't see performance being as good as a "standard" type slingshot.

What is it you're trying to achieve with this design? :?


Try drawing a pair of Thera Band Silver 300%.

I bet that you could not do it.

(Joerg can't either)

Now imagine 5 pair of silver bands.

This design has the potential to be more powerful than any compound bow made today.

BoyntonStu

Unread postPosted: Mon Aug 17, 2009 2:27 pm
Author: Moonbogg
How do you hold that thing? Do you stab yourself in the groin with that pole?

Unread postPosted: Mon Aug 17, 2009 2:53 pm
Author: twizi
wow that a big one it a little weird tho
ps next time edit some people get mad at it

Unread postPosted: Mon Aug 17, 2009 3:25 pm
Author: MRR
Stu you should have written that the "strange" design is part of the cocking system. Didn't got it at first.

The upper part is mounted with a hinge....

Unread postPosted: Mon Aug 17, 2009 4:10 pm
Author: boyntonstu
MRR wrote:Stu you should have written that the "strange" design is part of the cocking system. Didn't got it at first.

The upper part is mounted with a hinge....


"A triangle that flips down to hold the right angle is definitely needed. "

Sorry, I thought that the need for a triangle explained the cocking mechanism.

( The strap hinge pivot pin is clear in the photo).

It is a brute of a strange slingshot.

AFAIK No one has ever done a slingshot this way.

I think that it is logical to have a built in mono pod for steady holding and aiming.



BoyntonStu

Unread postPosted: Mon Aug 17, 2009 4:35 pm
Author: JoergS
From now on, I'll be real friendly to people with crutches and walking sticks! :) :)

Unread postPosted: Mon Aug 17, 2009 7:46 pm
Author: boyntonstu
I added 3 photos to the first post and a few comments.

The single pulley hoist made it much easier to draw and the tied off rope becomes the anti swing up locking mechanism.

BoyntonStu

Unread postPosted: Mon Aug 17, 2009 9:14 pm
Author: King_TaTer
That's a pretty interesting way to make a sling shot. It's huge but I'm sure it works well. Even more energy could be stored by cocking the arm over 90°. however that would require some serious leverage, lengthening of the strings and different hinge design. Good luck with this slingshot.

I'm pretty sure I've seen crossbows that use this technique but can't seem to find a link at the moment.

Unread postPosted: Mon Aug 17, 2009 9:34 pm
Author: boyntonstu
King_TaTer wrote:That's a pretty interesting way to make a sling shot. It's huge but I'm sure it works well. Even more energy could be stored by cocking the arm over 90°. however that would require some serious leverage, lengthening of the strings and different hinge design. Good luck with this slingshot.

I'm pretty sure I've seen crossbows that use this technique but can't seem to find a link at the moment.


At 90* the vertical becomes a mono pod (fence post) that keeps everything steady for aiming.

No weight for you to support.

I can add as many rubber bands as needed.

I would like to see the similar cocking crossbows.

BoyntonStu

Unread postPosted: Tue Aug 18, 2009 3:31 pm
Author: boyntonstu

Unread postPosted: Tue Aug 18, 2009 3:35 pm
Author: Hubb
[youtube]http://www.youtube.com/watch?v=_CeLFIZXQaQ[/youtube]

First shots.


I fixed it for ya. :wink:

BTW, I think the entire design is wonderful. Very nice. But I do have one question: Why would you want to shoot it at a target that sits that close to the vehicles? It looks like it is just begging to tear some paint.....