Revolving Cylinder?

[radar]

Hello people,

I am currently working on a replica of the demoman's Grenade Launcher from TF2. However I need some help with the revolving mechanism. I would like the cylinder to rotate to the next chamber on each trigger pull. As of now I'm trying to solidify a Rack and Pinion idea, but any help would be appreciated.

radar

 

[Wes R]

Have you looked into Nerf guns with the cylinders or the cheap knockoffs? Might be easier to cannibalize those to see if you can use it or scale it up.

 

[radar]

Have you looked into Nerf guns with the cylinders or the cheap knockoffs? Might be easier to cannibalize those to see if you can use it or scale it up.

I did look at a nerf gun like that, however the distance from the trigger to the cylinder is too much for the part. Also the mech itself is rather complicated :/

 

[vixr]

an electric motor in the stock controlled by the trigger, a drive shaft, a drive gear and a driven gear on the cylinder?

you would need a battery pack and a simple pulsewidth controller (555 timer) to time the rotation of the cylinder?


...actually, a simpler design would be a square drive shaft sticking out of the stock that slips into a square socket on the cylinder.
The more I think about this the more complicated it gets...the timer circuit couldn't supply enough current to turn the motor, so you would need to actuate a relay with the timer that could supply the motor current. You are looking at a simple circuit, but when you add small relays the price starts going up. There is a website that could possibly supply most of the hardware and components... CLICK HERE

 

[Wes R]

an electric motor in the stock controlled by the trigger, a drive shaft, a drive gear and a driven gear on the cylinder?

you would need a battery pack and a simple pulsewidth controller (555 timer) to time the rotation of the cylinder?


...actually, a simpler design would be a square drive shaft sticking out of the stock that slips into a square socket on the cylinder.
The more I think about this the more complicated it gets...the timer circuit couldn't supply enough current to turn the motor, so you would need to actuate a relay with the timer that could supply the motor current. You are looking at a simple circuit, but when you add small relays the price starts going up. There is a website that could possibly supply most of the hardware and components... CLICK HERE

I second electronic goldmine, they charge a flat rate so if you see more than you need get it otherwise you might end up paying 7.95 to ship a handful of small parts.

 

[vixr]

sorry.

 

[vixr]

sorry, I got carried away

 

[radar]

The thing is, the way the prop needs to be designed is that the stock ( and therefore any shafts coming from the trigger ) are at an angle where it joins to the cylinder assembly.

 

[Jaded Monk]

I'd sketch this out, but I really shouldn't even be online right now. Just a quick thought.

Think about the design of a retractable pen. You may not know it, but the internal mechanism rotates every time you depress it. In fact, with some models, if you take out one component, all they do is rotate every time you depress the button.

The top (internal) part of the trigger will push a cam against one of a series of mating cams in a shaft running up the cylinder. Each trigger pull pushes forward (force translates to downward) on one side from inside the cylinder shaft. Being round, the cylinder has nowhere to go but to rotate. Friction will be your enemy. You might even get a satisfying "Click" when the cylinder rotates.

 

[vixr]

The thing is, the way the prop needs to be designed is that the stock ( and therefore any shafts coming from the trigger ) are at an angle where it joins to the cylinder assembly. View attachment 229123

Ahhh, I see. I googled the gun and it looked straighter in the image I saw...I wonder if you could use something like a bicycle speedometer cable instead of a shaft...

 

[Robert Allen]

What about a the cylinder being a spool driven by elastic under tension, with a hidden pawl like on a revolver that retracts as you pull the trigger then snaps forward to grab hole or cut as it rotates around? You'd have to cock the thing every 6 shots or so by manually counter rotating the cylinder to re-tension the elastic.

 

[radar]

I'd sketch this out, but I really shouldn't even be online right now. Just a quick thought.

Think about the design of a retractable pen. You may not know it, but the internal mechanism rotates every time you depress it. In fact, with some models, if you take out one component, all they do is rotate every time you depress the button.

The top (internal) part of the trigger will push a cam against one of a series of mating cams in a shaft running up the cylinder. Each trigger pull pushes forward (force translates to downward) on one side from inside the cylinder shaft. Being round, the cylinder has nowhere to go but to rotate. Friction will be your enemy. You might even get a satisfying "Click" when the cylinder rotates.

This. this is nice. I'll have to look into this one more.