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The Slingshot Channel Thread

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Unread postAuthor: boyntonstu » Fri Jun 11, 2010 7:44 am

JoergS wrote:
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.


A 80 cm draw is for 20 cm rubber for a 5:1 ratio, correct?

My butterfly draw length measures 114 cm.

My guess is that your butterfly draw length is longer than 114 cm.

What is the initial rubber length in your powerful aluminum clad slingshot?

Using that rubber in a triggered rifle would be awesome.

I visualize a pouch holder/trigger made with hemispheres in a pliers arrangement that envelope the spherical ball inside the pouch.

On second thought, a hole on both sides of the pliers mechanism would be much easier to make.


Have you tried a shaped pouch and/or pouch holder?
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Unread postAuthor: JoergS » Fri Jun 11, 2010 7:55 am

The 80 cm would require 16 cm bands. 16 * 5 = 80.

My half butterfly draw length is 137 cm. Half butterfly means that the elbow is locked tight, just the upper arm is pulled back as far as possible.

I did try shaped pouches, made from Kydex. Works great.

You may go ahead and make a slingshot rifle with the 137 cm / Double Thera Band Blue setup. I cut it 14 cm at the fork and 9 cm at the pouch, two layers per side, 25 cm long (max. etxtension is in fact 550%).

This gives you about 70 Joules of energy with a 19 mm lead ball.

I could easily make such a rifle, but I have to keep the legal issues in mind as I said. Maybe I should come over to Florida for the project! :-)
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Unread postAuthor: boyntonstu » Fri Jun 11, 2010 9:33 am

Welcome to Florida.

My archery bow draw is 82 cm.

My far back as possible draw is 117 cm.

Can you visualize a Kydex pliers grip trigger and/or Kydex cups on a steel trigger?

BTW My Trom-Boy pressurized to 40 Bar is producing 430 Joules .
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Unread postAuthor: JoergS » Fri Jun 11, 2010 9:39 am

I would keep the trigger the way how I constructed it, and use leather pouches. Kydex does not have any significant advantages over leather.

The round rollers on the release part needs to be changed to a slight hourglass shape, so the position of the ball on the pouch is reproducable.

Easy to make and effective.

Jörg
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Unread postAuthor: boyntonstu » Fri Jun 11, 2010 10:24 am

JoergS wrote:I would keep the trigger the way how I constructed it, and use leather pouches. Kydex does not have any significant advantages over leather.

The round rollers on the release part needs to be changed to a slight hourglass shape, so the position of the ball on the pouch is reproducable.

Easy to make and effective.

Jörg


Two welded on washers spaced 25 mm apart per roller?
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Unread postAuthor: JoergS » Fri Jun 11, 2010 10:51 am

No, I think a gentle curve in the roller itself would be better. Less danger that the rubber gets stuck. Very easy to do in the lathe.
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Unread postAuthor: boyntonstu » Fri Jun 11, 2010 11:11 am

JoergS wrote:No, I think a gentle curve in the roller itself would be better. Less danger that the rubber gets stuck. Very easy to do in the lathe.



Your trigger is basically a fork that you pull down to release the rollers, correct?

Are rollers necessary or will rods or smooth bolts suffice?


My Big Shot Sling shot had one side fixed and the trigger released the other side of the pliers.

Is there a great accuracy benefit in a symmetrical release?

One moving part is much easier to make than 2 and if the release is consistent, it may be O.K.
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Unread postAuthor: maverik94 » Fri Jun 11, 2010 11:34 am

Great! I love how you keep coming out with original slingshot designs!
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Unread postAuthor: JoergS » Fri Jun 11, 2010 11:42 pm

boyntonstu wrote:Your trigger is basically a fork that you pull down to release the rollers, correct?

Are rollers necessary or will rods or smooth bolts suffice?


Yes, just a fork that I pull down. Easy and effective. The lever is quite long, so friction ain't a problem.

It's all about consistency. A one sided release may work, but my experience is that ball bearings and two moving parts are simply more consistent = accurate. The main advantage of a slingshot pistol/rifle over a simple fork IS accuracy, after all.
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Unread postAuthor: JoergS » Sat Jun 12, 2010 3:07 pm

This weekend's slingshot is an Ergo Shooter, made from a massive 2" x 2" amaranth block. That wood is hard! It took many hours to bring it into shape, and the polishing took even longer. It is incredibly dense. And red!

I used a flat steel bar (6mm) as the fork, to allow a low fork even though it is not a "W".

Used the clamp-on method for a change, got a bit sick of the messy look of rubber band attachments.

The bright red color does not come out very well in the photos, sorry. The dense, uncoated wood feels great in the hand!

I put on seven layers of Thera Black per side, the equivalent of Hunter bands. It shoots great.

Image

Image

Image

Jörg
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Unread postAuthor: Gun Freak » Sat Jun 12, 2010 3:23 pm

Looks very clean and comfortable! Good job!
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Unread postAuthor: boyntonstu » Sat Jun 12, 2010 6:46 pm

Better watch it, the handle shape in the palm of your hand is getting pretty close to phallic!

Even your words are close:

"The dense, uncoated wood feels great in the hand!"


(Look at the middle photo.)
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Last edited by boyntonstu on Sat Jun 12, 2010 7:17 pm, edited 2 times in total.
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Unread postAuthor: spudtyrrant » Sat Jun 12, 2010 6:58 pm

boyntonstu wrote:Better watch it, the handle shape is getting pretty close to phallic!
well technically thats ergo :lol: :roll: :lol:
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Unread postAuthor: JoergS » Sat Jun 12, 2010 11:48 pm

This is way too small to look phallic... at least for German standards! :D
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Unread postAuthor: Ranger » Sun Jun 13, 2010 1:02 am

Just went through all 43 pages.....

All I can say is WOW

You are the slingshot master of germany, taking such a simple toy and turning it into an extremley powerful work of art. I'm going to have to buy a slingshot now.

Keep up the good work :thumbleft:
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