# Prop building Thought experiment



## dscrimager (Jun 6, 2008)

I've built a new prop effect which I'm not going to detail just yet but instead I thought I would post the parameters that I worked within and see what thoughts others have to solve the problem. Then I'll post the working solution that I've come up with if others want to do something similar...

I'm in love with special effects and always want something that is believable. This year I have pirates but with a little twist.. I have a pop-up Spaniard that is shooting at the pirates (and insulting them along the way) from a fort guarding the gold. As part of that prop, I wanted to have a gun "pop" that is believable..but:

- I don't want a one shot that I have to stand around and reload, but it would acceptable to reload/reset a few times a night...
- I want it triggered by a prop controller so I don't have to trigger it
- No way will some recorded gunshot do it for me
- No way can I use real guns (blanks or not) or I would have the Chicago PD shut me down and since Halloween is on a Saturday I would probably sit in lockup until Monday morning...so not TOO believable
- it has to work outside in pretty much any weather (although it will be somewhat sheltered and not directly wet or rained on)

So, with all the fantastic prop designers on this board, how would you approach this? This is intended as a thought experiment to come up with ideas and then if there is enough interest in this specific effect I am happy to share my system with a tutorial. Either way, if anyone wants to duplicate it I am happy to share the design.

Freshly Doug


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## dflowers2 (Mar 5, 2007)

I vote for a small air cannon powered by propane with an ignition source, bwahahaha!

I would love to know how you did it and to see some video. Now where's my fire extinguisher?


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## dscrimager (Jun 6, 2008)

*Air cannon was my first idea*

In fact I ordered one from Minions ( hopefully it'll ship soon) and that's what we are building into the cannon firing at the fort....

I didn't go upsize that to utilize propane... yet....

Freshly Doug


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## bourno (Jan 21, 2006)

I thought maybe a nice hammer swung onto a thin piece of metal. Have fun playing with the air cannon.


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## The Watcher (Sep 13, 2008)

I was thinking about a solenoid rigged to a cap gun. That would give you 50 shots. I would love to see it, when you finish.


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## joshua17ss2 (Jan 10, 2008)

you could probably get a bunch of the primers from a muzzle loading shop, and make a gravity fed clip so they would drop in to place and use a solenoid to strike them, 
From my experience a lot of the bang is from that primer and that would give you the sound and a bit of light. with out having a real gun.


Maybe hold them together with some strips of tape (effectivly a cap gun on steroids. )


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## dscrimager (Jun 6, 2008)

*some very interesting ideas ...*

The watcher got it... although I cannot come up with a 50 shot version...
I used three 8-shot cap guns and set up three air cylinders to pull the triggers.
I used the 8-shot because they use ring caps which are much more reliable than strip caps. I made three because I did not want to reload all the time and this will fire one shot every few minutes.

For one firing unit:
Cap gun ~ $1.50 from amazon
ring caps ~ $2 for 800 shots
cylinder ~ $10 from ebay
flow controls and selenoid ~ $40

So not cheap for this effect, but nice sound and smell to go along. I'll not get the flash visible to visitors but the gun that is "firing" has some LED's that I'll blink before I fire the cap gun.

These can be repeatably built so if you want more than 8 rounds, you either reload or add more units. I plan to have to reload about once an hour since my prop will only fire once every 3 minutes as part of an overall show and I have 24 shots this way. I can reload all three guns in about 20 seconds since the front of these guns swings down and this design leaves that easy to accomplish.






Sorry for the crappy audio, my camera doesn't seem to pick up the satisfying "POP" that this makes....and I see the lighting is bad. But, if you look at the picture below and suffer though the video I think you'll see how it works.

Let me know if it's not clear how it works. I did have to fiddle around to make the springs "dual rate" with some zip ties in order to have the strings/springs loose enough to allow the guns to reset but then pull the string tight to actually pull the trigger.....Once critical element is that I drill a small hole in the trigger and then knot the cord going through. Another critical element is to have the cylinder pull slowly but firmly. The springs allow for lots of variation in positioning and don't break the trigger. The slow pull keeps the stress on the gun and string down. I use two eyes to guide the string along the sides for the gun and screwed the guns into cleats on the side. The clamps keep the guns from separating at the seams. I dremeled off the trigger guard and the front of the gun ( being careful not to mess with the shaft that holds the cylinder in place). With the plugged barrel ends gone they are much louder.

I have already programmed my Prop-1 (Efx_Tek ROCKS) to fire one of the cap guns ( and to switch through them sequentially until all three are empty) during each iteration of the prop coming up triggering.

I ruled out servos since the pull on the cap guns is actually pretty hard. I ruled out pushing on the triggers directly since that seemed very hard and likely to slip off. I ruled out strip caps since I could not find reliable guns and got lots of squibs. I ruled out pyrotechnics since they are slow to reload and I didn't want to buy a lot of them. I ruled out .22 blanks because I don't want to sit in jail ( see previous post). I ruled out building anything to actually strike the caps or blanks since the mechanism to shot and load another round is pretty complex for anything other than single shot.

Now I have hear tell of cap guns that will fire multiple ring caps ( not strip caps) in one load but cannot find them. If anyone comes across anything affordable that can hold more shots of the rings caps please let me know.

So, Halloween night I'll have some gunfire to go along with my Cannon BOOM.....

Freshly Doug


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## spinman1949 (Jun 29, 2009)

*gun powder*

Hmmm !!! I like your idea. I think a little step up from the cap gun would be cool. I am a bit of a pyro. Back in my younger years, I used to make firecrackers. They were very safe. I used model rocket igniters for the fuses and the powder was completely inert and would not ignite if struck like gunpowder does. I am thinking small pill capsules filled with gunpowder. Now how to strike them and have repeater. Hmm !!!


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## Just Whisper (Jan 19, 2009)

I agree. Great idea, very ingenious set up. Nice effect. But I would want a little more "bang" than a cap gun. Seems like the sound would get lost in all the other noises around it. I am curious why you were against recorded live gunshots? you could adjust the volume so you can make it as loud as you want.


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## dscrimager (Jun 6, 2008)

*I guess I could try a recording*

but I haven't heard one that really has that snap that I am looking for from equipment I am willing to put outside...It's a pretty good bang and has the right amount of echo but I am sure it will not be too loud to be mistaken for real gunfire ( I do live in Chicago.....) plus I get a little of the powder burning smell. I would like to use a louder source like blanks and a blank firing gun but that got even more expensive although you could easily adapt my device to fire a starter pistol, for instance, ...It's basically a trigger pulling device...

Freshly Doug


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## The Watcher (Sep 13, 2008)

It wouldn't be that hard to put a mic close to the gun to make this louder if needed.


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## Warrant2000 (Oct 8, 2008)

Take to short lengths (about 18" long) of 2x4 and smack them together. You'll get a loud and realistic gun sound.


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## billman (May 3, 2006)

Why not amplify the capgun like a megaphone. Pirate guns are kind of shaped that way! Here is a patent I found that does it:

http://www.freepatentsonline.com/4598491.html


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## dscrimager (Jun 6, 2008)

*The megaphone idea is good*

We were experimenting with putting funnels in the cut-off ends of the cap guns for amplification. But, now, I've found a supply of relatively cheap .22 Cal ($25) blank firing pistols and have ordered one to see what the step up in sound would be.

I should be able to use this mechanism to fire it since it's also a revolver.

Ohh, and the gun the Spaniard is firing has been converted to look like a blunderbus which is I believe what you are referring to,...( although the sound is not coming from there)...

(insert evil laugh here)

Freshly Doug


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## billman (May 3, 2006)

The idea sounds like Monty Python where the french man taunts them:





Classic! "I fart in your general direction!"....I was thinking you could make your Spaniard instead of shooting a gun do this (Franknfarter):


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## dscrimager (Jun 6, 2008)

*That is just TOO funny*

It IS basically kind of like the taunting scene, he's going to rise up, say an insult, shoot and then say something else,... all basically in pirate speak though
"Arggh, back to Davy Jones locker with you..." Bang, " I'll get you next time you barnacle butt"

Something like that with different sayings for pre and post shot...

The period up to the shooting is going to be some crowd noise and banging pikes (the tops of which will be seen moving up and down over the fort wall) in the background,.. "Don't let em get the gold", and so forth getting louder and louder until he pops up...

Freshly Doug


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## billman (May 3, 2006)

That's a very good idea. I would just be concerned about how loud a .22 would sound. They are pretty loud and the sound can echo. All you need is 1 phone call. If you are shooting them off constantly through the night, someone is bound to get annoyed. 

I think the capgun idea or compressed air could get you where you want without spending the weekend in jail. Good Luck!


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