3/4" exhaust valve cannon
Posted: Tue Apr 03, 2007 12:31 am
I built this last year, one of the most powerful I've ever built using my unique (as far as I've found so far online) construction technique featuring high-strength epoxy as opposed to standard fittings. It's got a 34" barrel and is filled/fired through the same schrader valve. The reason I can do this and still get great performance is the tiny pilot volume, as the piston can only move back a little more than 1/8" (approximately 25% of the barrel diameter and all that is neccessary for maximum flow). The cast epoxy piston is also lightweight, a near perfect fit and very low friction.
For more detailed information on using epoxy, check out the how-tos here and here.
The beast:

A diagram of the breech end internals:

I had a lot of fun with this particular creation, here's the damage videos.
cell phone shot with a marble:
[youtube][/youtube]
and the bits I managed to recover:

coffee can filled with water shot with a marble:
[youtube][/youtube]
entry/exit holes:

coffee can filled with water shot with multiple lead BBs:
[youtube][/youtube]
coffee can shot with a whiteboard marker:
[youtube][/youtube]
computer mouse shot with a marble:
[youtube][/youtube]
computer speaker shot with a marble:
[youtube][/youtube]
flatbed scanner shot with a marble:
[youtube][/youtube]
electric kettle filled with water shot with a marble:
[youtube][/youtube]
diving mask shot with a marble:
[youtube][/youtube]
and last but not least, xmas angel with a head full of red paint
[youtube][/youtube]
For more detailed information on using epoxy, check out the how-tos here and here.
The beast:

A diagram of the breech end internals:

I had a lot of fun with this particular creation, here's the damage videos.
cell phone shot with a marble:
[youtube][/youtube]
and the bits I managed to recover:

coffee can filled with water shot with a marble:
[youtube][/youtube]
entry/exit holes:

coffee can filled with water shot with multiple lead BBs:
[youtube][/youtube]
coffee can shot with a whiteboard marker:
[youtube][/youtube]
computer mouse shot with a marble:
[youtube][/youtube]
computer speaker shot with a marble:
[youtube][/youtube]
flatbed scanner shot with a marble:
[youtube][/youtube]
electric kettle filled with water shot with a marble:
[youtube][/youtube]
diving mask shot with a marble:
[youtube][/youtube]
and last but not least, xmas angel with a head full of red paint
[youtube][/youtube]