'Toy' machinegun

[Dangerous]

Hi,

I have an idea, and thought I might share it with you. Maybe one or two of you would have some input.

The idea is simple: Build a make believe machine gun, and then add vibration as it is 'fired', and speakers to make it sound realistic (just not as loud of course).

The machine gun I am thinking of is a 50 calibre M2HB, similar to the following picture:

**broken link removed**

What would you suggest I use to generate the appropriate amount of vibration as the gun is 'fired'?

What kind of amplifier would I use to make it real loud?

Please note this is not intended to be carried around. I am thinking of using a motorcycle battery in a ammunition box as the power source with the gun itself mounted on a stand or tripod. It isn't going to be one man portable.

This will hopefully be used as a stand-off weapon in a lasertag field (https://www.lasercombat.com). If it is popular and not too expensive to do, we may make a couple.

Thanks

 

[Johnson777717]

hmm. Do you know how much your model will weigh? I'm thinking that using a pneumatic cylinder might be a good way to go with simulating the recoil and thus the vibration. The cylinder stroke could be around 1 inch and cycle at a rate similar to the firing rate of the real mechanism. You'd have to find a relay that would cycle the pneumatic valve at a rate that is acceptable. Of course, you could build a simple 555 timer circuit which cycles the relay, thus cycling the pnematic valve. The 555 timer could be triggered by the actual trigger mechanism, using some sort of electric contact, or physical switch mounted at the rear of the trigger stroke. You may get lucky and find that the pneumatic discharge could effectively simulate the actual firing. That is, if you have compressed air available?

 

[Johnson777717]

Also, regarding the sound, what type of player are you planning to use to actually play the sound? Is the sound going to be fed into the gun from an outside source? Or are you planning to have the player included within the gun itself?

I know of some simple tone generator circuits that you can probably tailor to sound like the percussive and metallic sound of machine gun fire. Most of these are 555 timer based. I've never amplified these sounds, so I don't know what kind of sound quality you will receive. There are literally hundreds of amplifier circuits to run off of 12Volts. Are motorcycle batteries 12v? The amplifier you need may depend on the type and impedance of the speaker that you are planning to use.

I'm not too familiar with more progressive synthesizing methods, but I'm sure they are out there.

The project is definately possible, with some simple engineering and consideration to what resources you want to use.

 

[Dangerous]

Do you know how much your model will weigh

I am thinking less than 30 kilograms plus tripod, plus battery.

That is, if you have compressed air available?

Nope. I don't have compressed air available.

what type of player are you planning to use to actually play the sound

I was thinking an ISD device. Cheap, simple to use, and easily added to a PIC circuit.

Is the sound going to be fed into the gun from an outside source? Or are you planning to have the player included within the gun itself?

The sound will most likely come from a speaker mounted onto the gun. I am thinking about adding a couple of armour plates to the front of it. These are what they sometimes place on the front of Aircraft carrier mounted versions of this weapon. The plates would easily hold a couple of car speakers. Waterproofing may be an issue though.

Are motorcycle batteries 12v

I believe so.

Good ideas so far.

For the vibration, how about a 12 fan motor, similar to what you might find cooling the radiator in a car. I could offset a striker on the rotor shaft, and let it strike the inside of the gun. The only problem is that its probably low torque.
On the other hand, maybe a windscreen wiper motor and a gear with a similar offset striker.

 

[e]

maybe you could add some solenoids on the inside that actually smack into the internal sides of the gun to give a recoil like effect. I think the fan motor with possible a D weight on it would be more like wobble than like recoil.
If the solenoids have a spring return you can simply pulse them with the firing sound.
athough to get a good effect you may need some large solenoids (starter type solenoids) and thats a lot of current, maybe a few solenoids and a weighted motor...?