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Unread 10-08-2012, 01:17 AM   #1
Dictamnus Albus
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post apoc. gun, what style

ive been contemplating a post apocalypse multi-gun for quite awhile,

my first idea was to shape some wood, hollow it out, and put in the "guts"

but recently, after i saw it as a post apoc. item, rather than fantasy,

i started to think maybe i should make all the mechanisms then framework it,

im partially aware of the pro/con for each, but some other opinoins would help

also which would be easier/cheaper (relatively speaking)
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Unread 10-08-2012, 08:38 AM   #2
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It sounds like you are trying to build something that functions. Your post asks extremely broad questions. Without an image of your goal item, we really can't answer you.
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Unread 10-08-2012, 11:41 AM   #3
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Adding to Penlowe's comment, a websearch for "multi-gun" returns a bunch of sites talking about shooting competitions where you switch between multiple guns. So what is a "multi-gun" in this context?

Further, what do you mean when you use "framework" as a verb?
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Unread 10-08-2012, 10:46 PM   #4
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by multi-gun, i mean a singular unit that has multiple "barrels" in order to fire different
types of projectiles

the gun is intended to be easily created, repaired, and handle what ever might be available for ammo,
also for long term viability it would be a non-firearm (no explosive/propellants)

i havent finalized a design nor can i draw/sketch worth a darn so pics are kinda out of the question, but ill try to describe it in some detail

i was thinking along the lines of a short riffle, or a large pistol,
main barrel would launch projectiles via a spindle (similar to a pitching machine)
and be able to handle bolt and semi/spherical rounds
(torsion would be generated by crank, or a ratcheting lever)

and a side barrel would use disk like or other semi-flat rounds like coins or arrow heads
launched using a rail type catapult
(like the "slide" in a stapler but in reverse)

by framework i mean, to make a structure to hold everything in place,
im bad with terminology, but i guess itd be like a gun made from the inside out, and not encasing it, as to make it easier to keep track of wear, and hopefully ease of access for maintenance

Last edited by Dictamnus Albus : 10-08-2012 at 10:51 PM.
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Unread 10-09-2012, 02:15 PM   #5
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I completely understand not being able to draw. But when building things that have never existed, it can actually be worth the effort of first learning how to draw. Specifically, learning proper drafting techniques to produce technical type drawing. I've always been a miserable drawer, and I still am, but I've been teaching myself to draw by skimming through public domain Google Books on drafting and technical drawing, and reading/copying images from US Patent Applications.

Alternatively, you can teach yourself to use CAD software, but the friendlier software tends to be pretty expensive (thousands of dollars, yikes!), and a lot of the resources for learning it are expensive too.

So if you want something to be realistically practical, as opposed to a genius with infinite resources Iron Man type design, then you might be overdoing it a little. In this scenario, you want something that could be made with few resources, using mostly scrounged parts. You want to stick to mostly proven designs, since they will be more reliable, and you want the finished product to be lightweight, so it can be easily carried on foot, and can be quickly drawn, aimed, and fired.

An arrowhead propelled by a spring on rails wouldn't work well, as it would tend to not fly straight without an really long rail. This is part of why musket barrels were so long. It would force the ball to build up a straight path, and it would let the gases apply as much velocity to the ball as possible. A spring propelled projectile with have a much slower velocity than a musket ball. Plus, if a ball tumbles about, it doesn't matter, if an arrowhead tumbles, it will go off course with wind resistance, and it will not strike with the pointy bit.

The disk shooters only work as well as they do because they first put spin on the disk, like a frisbee. This mechanism would only be deadly if you gave it a razor sharp edge, and that would be a very customized and labor-intensive projectile.

I'm not sure what you mean by spindle. I know of 2 major types of pitching machines. One uses rubber fly-wheels spaced one ball-width apart spinning in opposite directions at high velocity. The other uses a long lever-arm, spun at high torque. The first one would either require lots of power to keep the wheels spinning, or lots of time to spin the wheels up to full speed for every shot. The second would have balancing issues. Every time you tried to launch a projectile, the weapon would leap out of your arms, and likely smack you in the face.

It sounds like what you would really want would be some form of crossbow along with the tools needed to fashion your own bolts.
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Unread 10-09-2012, 10:02 PM   #6
Dictamnus Albus
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i was thinking along the lines of the old windlass cross bows
using a coil to store torsional power wich in turn spins the spindle/wheel

the rail part is something i thought up later on, after i thought of post apoc. viability
since having a way to use almost anything as ammo would be an edge in a senario where resources might be gone/limited
along with the stealth advantages of a non firearm

if i forgo the bullcrap if the rail and jus have an internalised crossbow (no risers)
what way would be cheaper, easier or more durable/reliable

my main choice of ammo would be marbles, bearings, and bolts
and my goal is to have a weapon capable of killing medium game
(this is not intended to be a prop or used outside of target shooting or perhaps hunting)

also messing with the idea of a tether/winch system for using bolt harpoons

Last edited by Dictamnus Albus : 10-09-2012 at 10:14 PM.
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Unread 10-09-2012, 11:20 PM   #7
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So you're talking about building a genuinely functional weapon, which starts to get off-topic for this board. And if you hurt anyone or anything using any of this advise, it's your own dumb fault.

anyway, it's turns out that crossbow bolts are surprisingly easy to make presuming forests still exist. The only tools you really need are an axe, a froe, a die (a hunk of steel with a hole punched in it), and a knife. You chop down a tree; chop it into bolt-lengthed logs, use the froe to split the log into 3/8'' square sticks. Hammer each stick through the die to turn them into dowels. You sharpen the dowels to a point with a knife, and you bake the point over a fire just short of charring it to harden it. If desired, you can nap either flint or scrap glass to make a harder sharper tip. You can either attach feathers to the end using home-made hide glue, or you can cut a notch and slide in a pieces of thin plastic or soda can aluminum to stabilize it. With a bit of practice, you can make a hundred bolts in an hour.

Things like marbles and ball bearings are not going to be able to penetrate enough under human power to kill medium game (deer). They're only good for small game like rabbits and squirrels. For that, you should just build yourself a quality slingshot and carry it separately.

I expect you would have less frustrations using a compression or extension spring as opposed to a coil torsion spring. It's tough to find coil springs that can store that much energy, and each shot would put a lot of strain on the rope/pulley mechanism.
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Unread 10-11-2012, 05:54 PM   #8
Dictamnus Albus
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back to what materials i should use

im thinking if i go "scrapyard tech" on it, the thing will tear itself apart
under the forces im aiming for

so if i dig out a good 3x6 chunk of lumber, how well would that hold up?
or perhaps i could use an old 22. as the base

a spring would have me using a slide(rail), or striker (like pool or pinball)

...aw, that means i end up with a spring powered rifle, i think that been done before

is it possible, with my original idea, using a gear assembly, an energy storage of some sort,
and a rotary projection aperati(spindle/wheel),
to generate enough force, to be a functional piece
if my intended lethal range is say, 35-50yrds

or am i looking at something that will only ever be a "functioning" piece with no useful application?
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Unread 10-11-2012, 07:12 PM   #9
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I'm still confused by what you mean by "rotary projection aperati(spindle/wheel)" in this context.

When you say "wheel", do you perhaps mean flywheel? where the energy is stored as kinectic energy in a big heavy wheel that's spinning really fast?

Or do you mean something that will be still until you pull the trigger, at which point it flings a projectile? If you mean that, I'd need to see a design, as I'm currently imagining you trying to walk around with a catapult in your arms, and that is impractical on many levels.

other than a spring, what sort of energy storage aparatus were you thinking?

Your standard spring-powered rifle is not designed to be lethal, or not to anything past small game. But that is because the spring is set by a single yank of the arm. By using gear or pulley system to crank a spring compressed, you store a greater potential energy by exerting greater movement. In other words, it takes 4 or 5 cranks of both arms, instead of the yank of just one arm. If you can find the right sort of spring (which is always a pain), you can make such a device every bit as strong as a crossbow.

One major problem in that situation is going to be one related to the conservation of momentum. As the spring changes shape (compresses or extends), it is going to cause a shift in the center of gravity of your device. If it is fast and heavy enough, it is going to kick in which ever direction the center of gravity moves, with enough force to yank the gun right out of your arms. Bows are nice because they are made of lightweight material, that overall moves fairly little.

As far as materials, it gets very complicated very quickly. You have to understand where forces are going to be applied on your design. Some portions would need to be steel, while some portions can be wood. The thickness of the steel needed, and the configuration all gets into lots of physics and engineering issues.

When talking about storing up this level of energy, it is very important to have the math right in your design, and within orders of magnitude of tolerance, or you can wind up with a part smashing through your face, and either killing you, or ruining your life.

Again, this is a good reason to not start designing "new" things until you fully understand and can build things that have stood the test of time. Often, "new" ideas aren't really new, you've just never heard of them because they don't work.
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Unread 10-11-2012, 08:23 PM   #10
Dictamnus Albus
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i mean something that stays put till triggerd,
as far as energy storage, the only way i know of to get a rotational force
is using a coil, and if i start dealing in reality, using a coils should get acceptable results

the more thought i put into it, with my astronomical math and engineering skills,
/pant on fire

i should jus stay with "functional but useless", as much as i hate to put effort
into something thatll only look nice,

cause like you said, with all the forces involved, done improper, its likely to fail catastrophically,
and with my luck, ill end up quadriplegic, and unable to finish killing myself

i think the best way i can internalize the mechanisms would to build a gun-stock like platform
then build a cap over it,

the hard part would be figuring out how to make it all work... oh my brain, it hurts already

though having my own portable catapult would be fun...
i think something of a shoulder mounted trap shooter should work splendidly

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Unread 10-12-2012, 02:54 PM   #11
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So you can build a hand-carried catapult on the small toy-scale moderately well. I think I've seen toys that launch things like bean-bags or small water balloons, and they fly 10-20 feet. They usually use surgical elastic tubing (the same thing commercial slingshots generally use).

I recommend you watch some videos of Pumpkin Chunkin', they can be extremely informative, as these people are trying to do a very similar thing to what you are doing: design and build an optimal device that launches a projectile at a very high velocity.

The trouble with a hand carried catapult is when you try to scale it up and get some serious velocity going. You see, a catapult isn't really designed to use its energy efficiently. They are designed to fling an object at high velocity in a high arc. To achieve this, a big heavy arm swings forward. After the projectile releases, momentum causes the arm to keep swinging. The result is that unless the base is ridiculous heavy, or the whole thing is heavily and securely bolted into the ground, it kicks like a mule. If it is a device held in your arms, you don't have the option to make it heavy or to secure it to the ground.
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Unread 10-12-2012, 05:47 PM   #12
Dictamnus Albus
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i was kinda joking about that, lol

but ya, if i find a toy lobber, ill probably give some thought into whether it would work for
such a device, just for kicks

also, pumpkin chunkin was awesome, the physics is over my head though,
centrifugal!? /mind blowing
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