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Pneumatic ideas

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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Pneumatic ideas

Unread postAuthor: Alanstone » Mon Nov 26, 2012 6:25 am

Having got to work out how much of this cad program works and having lots of time to work on it I put some ideas together.

Now I don't for a second think that this design will work and its not complete by any means. There are orings and threaded bolts missing all over the place. Also, I have done some calculations with regard to the pressures on the internals and some are far to high.

The ideas are as follows:

*CO2 feeds into 2/3rds of the tube containing the barrel thus acting as an expansion chamber.
The CO2 is fed from this expansion chamber to the piston to fill the chamber. A slide valve is used to pilot the piston. This slide valve is operated by a linkage to the trigger.
* The first 1/3rd of the tube acts as a suppressor. The gas expanding into this chamber is used to move the ammo down the magazine tube. This air is also used to reset the blow forward bolt. The magazine is also contained within the tube.

* A rubber detent holds the ammo back and also creates a seal. (I still want to find a way to make the detent adjustable to prolong its life).

* The internal chamber parts are designed modular for ease of manufacture. The idea is to sandwich some parts between those which will be bolted into the tube.

Please be so kind as to offer your expertise and insights as to how this design could become functional.
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Unread postAuthor: jackssmirkingrevenge » Mon Nov 26, 2012 8:31 am

Looks good, I like the way you're using air from the shot to help with loading.
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Unread postAuthor: Alanstone » Mon Nov 26, 2012 10:01 am

@JRS: I got a new program today called freecad. Its 3D cad and so far its really easy. It helping a lot with visualizing the parts :) . What do you think of the piston and bolt? Do you think it could work being fed air from the tube chamber like that? Just for reference the barrel is 700mm long and the tube is 50mm OD. Gun is 850mm total. I am very worried about having to replace the detent when it wears. That's why I started to thinks about the ammo pressed into the washer. It will probably need a setting screw to extend its lifespan I wish I could predict how long it will last. The tube could be 316 or 304 stainless but its going to be heavy. Perhaps aluminium? The tube wall thickness is 2.5mm
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Unread postAuthor: Alanstone » Mon Nov 26, 2012 10:02 am

@JRS: I got a new program today called freecad. Its 3D cad and so far its really easy. It helping a lot with visualizing the parts :) . What do you think of the piston and bolt? Do you think it could work being fed air from the tube chamber like that? Just for reference the barrel is 700mm long and the tube is 50mm OD. Gun is 850mm total. I am very worried about having to replace the detent when it wears. That's why I started to think about the ammo pressed into the washer. It will probably need a setting screw to extend its lifespan I wish I could predict how long it will last. The tube could be 316 or 304 stainless but its going to be heavy. Perhaps aluminium? The tube wall thickness is 2.5mm
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