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The Slingshot Channel Thread

All non-spudgun related discussion goes here such as projects, theories, serious questions, etc. All "off-topic" posts (aka useless posting, determined by moderators) will be removed.
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Unread postAuthor: MRR » Tue Jun 08, 2010 12:46 pm

Couldn't this be a possible solution ... Adding a hinge in the middle and using a lever?

Image
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Unread postAuthor: boyntonstu » Tue Jun 08, 2010 1:28 pm

MRR wrote:Couldn't this be a possible solution ... Adding a hinge in the middle and using a lever?

Image


Good idea.

However it needs a better trigger that can safely hold back a strong rubber.

The way I see it is to place the projectile in the pouch and place the pouch into a trigger/holder.


Big Shot Slingshot
[youtube]http://www.youtube.com/watch?v=_CeLFIZXQaQ[/youtube]


Once safely in place, the next step is to stretch the rubber.

The bar spreader would be one way of doing it.

The projectile is triggered as you pull it and the mechanism along a ratcheted rail.

A slip would safely brake like an elevator whose cable snapped.

My elevator:

[youtube]http://www.youtube.com/watch?v=_hom61NxuaE[/youtube]



My $0.02
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Unread postAuthor: JoergS » Wed Jun 09, 2010 2:21 am

The hinge idea would in fact be dangerous. The pouch could slip out of the locking bars.

I think to make this powerful, two things are needed:

- The trigger rmechanism is fine, just needs to be made out of thicker steel. 12 mm stainless will do.

- The ratchet idea would work, I would simply have the fork sliding along the "barrel". The sliding fork would have a handle underneath it (like a two-grip machine gun). The fork would have a locking position at minimal and maximal extension. To load, the rubber would be very slightly stretched, so the ball does not fall out of the pouch. To shoot, you would slide the fork forwards, lock it in max position and then fire.

I would use a tube with a rectangular profile as the barrel, and a thicker rec tube for the sliding fork.


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Unread postAuthor: boyntonstu » Wed Jun 09, 2010 7:11 am

JoergS wrote:The hinge idea would in fact be dangerous. The pouch could slip out of the locking bars.

I think to make this powerful, two things are needed:

- The trigger rmechanism is fine, just needs to be made out of thicker steel. 12 mm stainless will do.

- The ratchet idea would work, I would simply have the fork sliding along the "barrel". The sliding fork would have a handle underneath it (like a two-grip machine gun). The fork would have a locking position at minimal and maximal extension. To load, the rubber would be very slightly stretched, so the ball does not fall out of the pouch. To shoot, you would slide the fork forwards, lock it in max position and then fire.

I would use a tube with a rectangular profile as the barrel, and a thicker rec tube for the sliding fork.


Image



I believe that a fixed fork with the rubber coming from underneath and a sliding/ratcheting trigger is the way to go.

The projectile is comfy in its pouch and trigger with a locked safety on.

The rubber is limp.

You slide the pouch/trigger as far back as you can pull without strain.

You ratchet the rest of the draw.

Undo the safety, and fire.

BoyntonStu

(I am tempted to try it using one of my spreader bars.)
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Unread postAuthor: MRR » Wed Jun 09, 2010 12:45 pm

JoergS wrote:The hinge idea would in fact be dangerous. The pouch could slip out of the locking bars.


I thought about that as well but you could prevent that by adding two knobs onto the locking bars. Anyways, it was just an idea.

I'm certain you'll find an elegant way to solve the problem.
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Unread postAuthor: boyntonstu » Wed Jun 09, 2010 1:07 pm

MRR wrote:
JoergS wrote:The hinge idea would in fact be dangerous. The pouch could slip out of the locking bars.


I thought about that as well but you could prevent that by adding two knobs onto the locking bars. Anyways, it was just an idea.

I'm certain you'll find an elegant way to solve the problem.


I thought about drawing a 50 pound Theraband slingshot pistol/rifle and now I am convinced that ratcheting is not necessary.

All one needs is a locked projectile and a spreader bar anti-slideback rail.

With a foot rest and a two hand power lift, even 100 pounds would be easy.

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Unread postAuthor: JoergS » Thu Jun 10, 2010 2:43 am

Stu, the rollers would only shorten the barrel by 1/5th if you want the rubber limp in the pouch. Hardly worth the efforts and the additional wear (chafing).

I don't think it matters at all if the trigger/lock part moves or the fork part. But the fork part is lighter, so my preference would be to move that one.

And I think a little tension in uncocked condition is necessary, otherwise the ball may slip out of the pouch when you carry the weapon. I use the pre-tension in my Gatling, works great.
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Unread postAuthor: boyntonstu » Thu Jun 10, 2010 7:23 am

JoergS wrote:Stu, the rollers would only shorten the barrel by 1/5th if you want the rubber limp in the pouch. Hardly worth the efforts and the additional wear (chafing).

I don't think it matters at all if the trigger/lock part moves or the fork part. But the fork part is lighter, so my preference would be to move that one.

And I think a little tension in uncocked condition is necessary, otherwise the ball may slip out of the pouch when you carry the weapon. I use the pre-tension in my Gatling, works great.


You are drawing the rubber using a power lift method with your feet at one end of the sligshot.

As you pull to full draw, would you rather look down at the pouch/projectile aimed at your face, or the fork?

A 20% longer pistol barrel may not be what you desire.

For a rifle, I completely agree that an up and over is not necessary.

I can visualize a trigger pouch holder that would securely hold a ball with a limp rubber.

This is a mute point with an anti-slideback rail, because you could place an initial tension in the rubber at any level desired.

Drawing 50-100 pounds places the weight difference between fork and trigger into a minor category.
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Unread postAuthor: JoergS » Thu Jun 10, 2010 8:49 am

Only a rifle can ever make sense. A pistol simply does not allow enough acceleration. A slingshot pistol, like a crossbow pistol, is a weak toy. Not enough draw length.

Of course you don't want to look "down the barrel" when you draw out. But why should it matter which part moves? You are basically pulling two parts away from each other.
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Unread postAuthor: boyntonstu » Thu Jun 10, 2010 9:16 am

JoergS wrote:Only a rifle can ever make sense. A pistol simply does not allow enough acceleration. A slingshot pistol, like a crossbow pistol, is a weak toy. Not enough draw length.

Of course you don't want to look "down the barrel" when you draw out. But why should it matter which part moves? You are basically pulling two parts away from each other.


Imagine drawing a crossbow loaded with a bolt, backwards, with the point of the bolt facing you.

I would never do it that way.

Remember too, the ratcheting action would prevent the fork from traveling up the barrel as it prevents the pouch from traveling down the barrel.

In addition, even with an unloaded pouch, if released, the pouch will fly dangerously beyond the fork.


To each their own.
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Unread postAuthor: JoergS » Thu Jun 10, 2010 9:25 am

I don't want that stand-on method. It is not needed. Common ammo (up to .75" lead) does not need extreme draw force. You can simply push the grip with the attached fork to the front, using your arm and chest muscles.

My barrel length would be around 80 cm.

Band length would be 16 cm, stretched to 20 cm so the ball won't fall out of the pouch. So you have to push/pull 60 cm.

That would be enough for a fairly strong rubber band, and you could fire very quickly. Like a pump gun.
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Unread postAuthor: boyntonstu » Thu Jun 10, 2010 9:38 am

When I see you straining to butterfly draw a powerful slingshot, it does not look like the average person could do it.

Using your front fork grip design plus a ratchet would do it for a much weaker person.

Draw to 25 pounds and ratchet to 50.

BTW Have you measured the highest draw with a fish weight scale?

My toy crossbow pistol measures 50 pounds to cock.

A self cocking lever action 80 pound model is also available.

(The throw is too short for a slingshot).
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Unread postAuthor: JoergS » Thu Jun 10, 2010 9:51 am

You can pull a lot harder if you have a grip instead of a pouch, pinched between thumb and forefinger.

Don't forget that I still can not make a rifle with a shoulder butt. That would be illegal. I can only do something that is like a longer pistol. And even that is (legally) dangerous as soon as it is strong enough to be more than a toy.

So most of this will stay theoretical anyway.

I also have the self cocking 80 lbs slingshot pistol, it is quite weak.

My next project is shooting short arrows (flechettes) from the slingshot! Will test it in the vise extensively before I will start shooting freehand.
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Unread postAuthor: boyntonstu » Thu Jun 10, 2010 10:37 am

JoergS wrote:You can pull a lot harder if you have a grip instead of a pouch, pinched between thumb and forefinger.

Don't forget that I still can not make a rifle with a shoulder butt. That would be illegal. I can only do something that is like a longer pistol. And even that is (legally) dangerous as soon as it is strong enough to be more than a toy.

So most of this will stay theoretical anyway.

I also have the self cocking 80 lbs slingshot pistol, it is quite weak.

My next project is shooting short arrows (flechettes) from the slingshot! Will test it in the vise extensively before I will start shooting freehand.


What is your wingspan?

Most boxers measure 'reach' as the distance between outstretched hands, usually much longer than 80 cm.


OTOH I consider a boxer's arm length reach more significant.

If 80 pounds in a crossbow is considered weak, what is your strongest hand held pull?
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Unread postAuthor: JoergS » Thu Jun 10, 2010 11:14 pm

I am not saying that 80 lbs is not a heavy draw weight. I am saying that the SHOT from that pistol crossbow is weak.

I have a Razor Edge compound bow that at 60 lbs shoots with tremendous power. It is fairly small, too.

My reach is long, but the power is not evenly distributed over the full motion path. It is that 80 cm where you most of the strength. The max power curve falls steeply beyond that point.
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