Wrist Dagger - Scissor Jack Design

Weapons Master Joined : 07 Dec 2007 Posts : 1353

Hey Siripala, thanks for posting, we'd love to see diagrams of your hydraulic retractable blade. Take your time, finish your A levels, and then get back to us with something great!! And introduce yourself in the Welcome thread when you have a chance... Thanks! Very Happy

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"Genius - One per cent inspiration, ninety-nine per cent perspiration." - Albert Einstein

BladeMonger Age : 23 Joined : 22 May 2008 Posts : 21

Hey phyreblade, ive been watching this mechanism and im really impressed, i have been thinking all night long about how to fit the scissors and not occupy so much space in the case and i came up with this pretty crazy idea, why not using a double scissors syste, where the one in the case is larger and goes further and it also makes the 2nd one open, which will directly push the blade outside.

I think i have the whole system pretty much completed, after some drawings in the paper and using my trigger system, this might just work, im gonna try to create the system schematicly so you guys can see and later give me your opinnion.

BladeMonger Age : 23 Joined : 22 May 2008 Posts : 21

Heres the system, remember this is only the first part of the weapon, the principal case in the wrist.

Eventually i going to finish the rest of the scheme in the 2nd case that will be triggered from the wrist case.

Shwon in the image:
When the cable is pulled, the trigger system starts
The pin, which is yellow (attatched to the cable and placed in the trigger system- Red plate), will move the green plate (that is connecting the pin to the scissors) to the left and the pin locks
That pin movement will make 1 scissor's end to go forward, only 5cm is enough to almost open it all (probably, not shure)
The scissors will then push the wheel that is over the rail

Not shown in the image:
That wheel will move the second stage of scissors that will be inserted inside the middle blade case
the middle of the scissors will have a rail plate that will be moved by the wheel
the other ends of the scissor will be stuck to the spring cable ends
once the wheel starts pushing the blade ouside, the scissors open pushing the blade and the springs create the tension needed to make the wheel open the scissor

To close again, just pull a little the ring and the pin unlocks, letting the springs do the rest of the job closing it.

mind that the wheel is something like this

i hope this was clear.

BladeMonger Age : 17 Joined : 05 Apr 2008 Posts : 45

BladeMonger Age : 23 Joined : 22 May 2008 Posts : 21

BladeMonger Age : 17 Joined : 05 Apr 2008 Posts : 45

BladeMonger Age : 23 Joined : 22 May 2008 Posts : 21

Death Dealer Age : 17 Joined : 09 Apr 2008 Posts : 328

well i was looking at this design and your lock design and has wondering how it make the pivot points of the scissorjacks come together to make them expand? i know im missing something and have tried to find it but just cant see how.
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BladeMonger Age : 23 Joined : 22 May 2008 Posts : 21

Death Dealer Age : 17 Joined : 09 Apr 2008 Posts : 328

ooooook now i get it now. a very simple design i like it
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Weapons Master Joined : 07 Dec 2007 Posts : 1353

Hey Karlitos
Another nice diagram. The biggest problem i see is that your draw distance will be rather long. One of the reasons the tongs idea worked so well is that you only needed to open and close the tongs a short distance at the bottom in order to get a long extension. If you make it so we are in effect pulling the two bottom most pins of the tongs apart manually, the distance you will have to pull it will become more than can be comfortably taken up by a simple finger or wrist movement... PhyreBlade

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"Genius - One per cent inspiration, ninety-nine per cent perspiration." - Albert Einstein

BladeMonger Age : 23 Joined : 22 May 2008 Posts : 21

Weapons Master Joined : 07 Dec 2007 Posts : 1353

LOL sadly, it doesn't actually work that way... that kind of mechanism will actually work against you. A distance multiplier actually increases the amount of force you need to exert in order to accomplish any given amount of work. the converse is also true. The farther you have to pull, the less force you will need in order to accomplish the same amount of work.

In fact I think that simple little problem is perhaps one of the the biggest obstacles to creating mechanisms like these... I can guarantee you that whatever mechanism you come up with to mechanically shorten your pull length will increase the amount of strength needed to make it work...
Try it and see... PhyreBlade

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"Genius - One per cent inspiration, ninety-nine per cent perspiration." - Albert Einstein

BladeMonger Age : 23 Joined : 22 May 2008 Posts : 21

Weapons Master Joined : 07 Dec 2007 Posts : 1353

New Guy Age : 14 Joined : 20 Jul 2008 Posts : 6

what about this?

http://i44.servimg.com/u/f44/12/74/50/78/hidden12.jpg

Weapons Master Joined : 07 Dec 2007 Posts : 1353

This is basically a gravity knife. It will work, but is not really what we are looking for here... PhyreBlade

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"Genius - One per cent inspiration, ninety-nine per cent perspiration." - Albert Einstein

Xiphoid Fanatic Age : 16 Joined : 07 Jul 2008 Posts : 191

I have made a prototype for a new design.
Hopefully I can make it in some sheet steel, thick sheet steel...

Part A
It consists of firstly a blade. Connected to the end is a thin spring,
the kind you stretch, not compress.
The end of the spring not connected to the knife is the bottom of a metal box.
This rig is accompanied by a locking mechanizem that I will perect later.
This entire part has a sole purpose of locking the blade, with the spring stretched.
For example: You hold it upside down and shove down, and a quick jerk up,
letting the blade fall, stretch the spring, and lock in place.
I will show you this part's usefullness later.

Part B
Metal box with a scissor spring at the bottom. Each end of the scissor spring will have a
small, strong spring that you stretch, not compress.
This box's purpose is to propell Part A forward, and then lock it in place.

How it works:
Activate it, and the scissor spring propells Part A forward while giving it plenty
of momentum.
Part A is stopped quickly and locked into place.
The blade however, still has a great deal of momentum and continues forward.
It pulls the spring with it, and at the end, locks itself.

When you are done with the blade, and need to hide it quickly...
unlock the knife, and the spring will pull it back in.

Later, when you are in a safe location... or on the move...
Take entire Part A and shove it back into Part B (after unlocking it).
This will re-position the scissor spring, letting the device be ready for
another go.
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Thx Kashira for the Sig!!

Xiphoid Fanatic Age : 16 Joined : 07 Jul 2008 Posts : 191

This mechanism is almost identical to one of Phyreblade's earlier posts, only without the
worm gears and such, and with a thin spring attached from the blade, to the sheath that
does not hold the scissor spring.

Here is the design Phyreblade posted that is very much like my design.
[img]

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Thx Kashira for the Sig!!

BladeMonger Age : 23 Joined : 08 Aug 2008 Posts : 12

Hey scissor jack guys,

Been looking at your designs and I like what I see. I might take a crack at the scissor jack design myself after I finish my "all-spring" prototype, lol... Just an idea (that may have been suggested and I missed it): What if you used the scissor jack to pull the mechanism in and let the springs push/pull it out? Just a thought... dwarf

Weapons Master Joined : 07 Dec 2007 Posts : 1353

Yes that would be an easy modification, however I think we had decided not to do that for safety reasons... Better to have the blade accidentally retract than accidentally extend...
PhyreBlade

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"Genius - One per cent inspiration, ninety-nine per cent perspiration." - Albert Einstein

BladeMonger Age : 23 Joined : 08 Aug 2008 Posts : 12

Lol, good point... Maybe one of us can think of a safety mechanism for when not in use? study