Pump Action Hex Nut Slingshot (v2.0, w/ Blueprints)

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krayvis
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Joined: Fri Jan 24, 2014 10:25 pm

Pump Action Hex Nut Slingshot (v2.0, w/ Blueprints)

Post by krayvis » Tue Mar 11, 2014 8:54 pm

For those of you that don't know my inner child's enjoyment of destruction, I'm a huge fan of Jörg Sprave and his rubber-powered demolition devices. This is my second attempt to build something remotely as cool as what he does on a regular basis. It's a slingshot that launches 1/2" hex nuts, the easiest to obtain ammunition I could find at Home Depot.

Material is 1/4" plywood, which really means 0.2" thick pieces. Hardware is #6 screws, with some #8 machine screws for load-bearing parts. Front forks are machined from pine.

See attachments for blueprints. Colored version of overview PDF available at: http://www.theslingshotforum.com/f5/pum ... rts-33707/



Attachments
P50 Hex Nut Slingshot_Greyscale.pdf
(145.24 KiB) Downloaded 548 times
P-50 Oversize Parts.pdf
(34.76 KiB) Downloaded 491 times
P-50 Small Parts.pdf
(34.91 KiB) Downloaded 509 times
Last edited by krayvis on Mon Mar 31, 2014 9:32 pm, edited 3 times in total.

WillAdams
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Re: Pump Action Hex Nut Slingshot (v2.0)

Post by WillAdams » Tue Mar 11, 2014 9:30 pm

Very, very, very cool!

Interesting choice for ammunition --- what other things did you consider?

What's the poundage on the bands? Have you calculated efficiency / energy storage / release?

I've been thinking about reading The Practical Guide to Man-Powered Weapons and Ammunition: Experiments with Catapults, Musketballs, Stonebows, Blowpipes, Big Airguns, and Bullet Bows for a long while now.
Shapeoko 3XL #0006 w/Makita RT0701 Router w/0.125″ and ¼″ Elaire precision collets
Nomad 883 Pro #596 (bamboo)

krayvis
Posts: 47
Joined: Fri Jan 24, 2014 10:25 pm

Re: Pump Action Hex Nut Slingshot (v2.0)

Post by krayvis » Tue Mar 11, 2014 9:47 pm

For ammo, all sorts of stuff. I made a pretty weak slingshot that fired nail polish over the summer as a joke. But really, the next "weapon" I want to make is a DIY nerf gun. Similar to: http://makezine.com/projects/make-29/better-nerf-gun/

Draw weight is between 15-20 pounds, that's using two half inch wide strips of Theraband per side. On the first version of this I did, I tried up to 3 bands per side and that was very difficult to use, but it survived. The limiting factor is abrasion. When paracord rubs up against wood at high speed, even sanded smooth, it starts to abrade or even melt. I need to go over everything again with a higher grit sandpaper than 200. When the weather warms up, I'll test three and then four bands. Hoping to get close to around 100-120 MPH at the muzzle.

But there are a couple more projects in the queue before I get there. So much to make, so little time ...

MeanderBolt
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Re: Pump Action Hex Nut Slingshot (v2.0)

Post by MeanderBolt » Tue Mar 11, 2014 10:18 pm

Yay, another Krayvis vid!!! I am glad it worked for you. I have been curious since you mentioned that you were going to be building it.
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Build log

WillAdams
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Re: Pump Action Hex Nut Slingshot (v2.0)

Post by WillAdams » Tue Mar 11, 2014 11:26 pm

Interesting.

I picked up a set of Micro Mesh abrasive a while back and it's amazing the surface one can get w/ the stuff.

Made a crossbow when I was a kid using a leaf spring from a truck --- had to use a winch to cock it, which was fine until the stock broke when it was almost fully cocked.
Shapeoko 3XL #0006 w/Makita RT0701 Router w/0.125″ and ¼″ Elaire precision collets
Nomad 883 Pro #596 (bamboo)

krayvis
Posts: 47
Joined: Fri Jan 24, 2014 10:25 pm

Re: Pump Action Hex Nut Slingshot (v2.0)

Post by krayvis » Wed Mar 12, 2014 9:18 pm

Ooohh, that's not good. Investing in a bigger set of tools is something I've been meaning to do. Especially some high quality cutters, engravers, etc.

Here's some closeups of the slingshot.
Screen Shot 2014-03-12 at 5.08.27 PM.png
Screen Shot 2014-03-12 at 5.08.27 PM.png (297.24 KiB) Viewed 4520 times
Screen Shot 2014-03-12 at 5.09.26 PM.png
Screen Shot 2014-03-12 at 5.09.26 PM.png (472.71 KiB) Viewed 4520 times

Auarhau
Posts: 243
Joined: Tue Feb 25, 2014 8:46 pm

Re: Pump Action Hex Nut Slingshot (v2.0)

Post by Auarhau » Mon Mar 31, 2014 4:00 pm

Love the videos man. Make more!
ShapeOko 2. Nema 17 74 oz·in. GAUPS shield on Arduino Uno. DRV8825 Drivers x4 . Kress 1050 FME-1. Z Acme Screw. Threaded inserts table.

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