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Good ol' Boomer - damage pics and videos

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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Good ol' Boomer - damage pics and videos

Unread postAuthor: n05gr0th » Fri Aug 14, 2015 12:53 pm

This is my second air gun. I call her Good ol' Boomer. She can blast through nearly two 2x4s using lead and steel balls and will embed the same ammo deeply into a 4x4! According to GDDT I'm getting around 650-700 fps with 177 grain lead balls at full power, I'm a little skeptical of that though...
Specs:
Valve: 3/4" QEV piloted by a 1/2" QEV, this is then piloted by a 1/4" ball valve.
Barrel: 1/2" type M copper, 60" Long
Chamber: 3/4" steel pipe, 30" long
Operating pressure: 100 - 400 psi. Can go up to 600 but too scared.

Shooting at a water bottle with a marble
https://www.youtube.com/watch?v=umC-keTH4zE

Shooting a 1/2" steel ball through a wheelbarrow, the table behind it and 1" pine. Shot at 60 paces.
https://www.youtube.com/watch?v=JrtVrbW0nqQ

Hope you like the gun/damage pics. Any suggestions on improving ergonomics/reducing pilot volume would be welcomed!
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Attachments
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Full gun
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Close up of valve assembly
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2x4
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An old kettle
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The 4x4
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That's 3 inches deep!
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This little bugger passed through over 800 pgs of magazine! As a comparison, my .22 springer will struggle to make it through 100.
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Lead ball vs can filled with water
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Some more shots at the kettle.
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Re: Good ol' Boomer - damage pics and videos

Unread postAuthor: n05gr0th » Sat Aug 15, 2015 12:54 pm

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Re: Good ol' Boomer - damage pics and videos

Unread postAuthor: Ianbuckwell » Wed Aug 19, 2015 12:15 pm

I haven't watched all the videos as on my phone, but that is awesome power, what brand are the QEVs? And do you have to mo them with spring/pin hole?
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Re: Good ol' Boomer - damage pics and videos

Unread postAuthor: Doodmens » Thu Aug 20, 2015 6:05 pm

Very nice indeed! That looks very powerful to me. If the QEVs are the cheapies from ebay, how did you get them to work properly after modifying for chamber feed? I couldn't get this type to work but the black box QEVs work fine for me.

For reducing pilot volume, I saw that someone stacked rubber or plastic washers in their pilot chamber,still allowing for airflow but reducing air volume.

As for the ergonomics, I'd carve a nice hunting rifle stock for it and put a bipod under there because it looks heavy!

Cheers
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Re: Good ol' Boomer - damage pics and videos

Unread postAuthor: n05gr0th » Fri Aug 21, 2015 6:40 pm

@ Ianbuckwell - Thanks for the comment. The QEVs are from Alpha Technologies, ordered from Fastenal. They perform well and no sign of wear on the Pistons after 50+ high pressure shots. I think the cv for the 1/2" is 5 and the 3/4" is maybe 5.5. Nope, no modification required.

@ Doodmens - I fill from the pilot, not the chamber. That's a great idea, thanks. I have lots of washers lying around so I'll have to try that! If I don't open the BV adequately the piston vibrates in the QEV so I definitely need to reduce the pilot volume. It looks cool in slow motion though :p. As for ergonomics, that would look nice, but the gun is over 5ft long so I think a bullpup confit would be less ridiculous xD.
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Re: Good ol' Boomer - damage pics and videos

Unread postAuthor: Ragnarok » Fri Aug 21, 2015 8:23 pm

n05gr0th wrote:If I don't open the BV adequately the piston vibrates in the QEV so I definitely need to reduce the pilot volume.

I have to admit that I'm surprised. Boomer isn't that different to the way I've got HEAL set up - a 20mm piston valve piloted by a 1/2" QEV, connected by about 40cm of 8mm tubing to a 1/4" sleeve valve; all the valve flows, pilot volumes and the like are broadly similar. Even the same "S-kink" chamber - the only significant difference I can see with respect to their mechanics is the exact sizes of chamber and barrel*.

Still, I've never had "honking" problems with HEAL. Which of the valves is doing it? The 1/2" pilot?

*In that respect, I can definitely empathise with you about taking a bullpup approach! At one point HEAL had a 125cm (~49") barrel, but even that I eventually decided to cut it back to the 100cm (~39") on my original blueprints just to keep the lengths more practical.

Although, that said, I'm guessing Boomer has more like 6-7" behind the breech? HEAL's valve assembly is almost deliberately long at closer to 10", and it does obviously all add up.
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Does that thing kinda look like a big cat to you?
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Re: Good ol' Boomer - damage pics and videos

Unread postAuthor: n05gr0th » Fri Aug 21, 2015 10:46 pm

@ Ragnarok - it's no coincidence. Your cannon along with Dave_224's 600 psi launcher were my main inspirations!

I believe it's the 1/2", I can only avoid honking if I pull on the BV extremely quickly and fully so it must struggle to dump the pilot volume fast enough... I'm considering just spring-loading it so as to avoid fiddling with the fittings too much (they were a b*tch to seal). Do you think reducing the pilot volume between the 1/2" and 3/4" QEVs would get better results instead?
Here's a video of a failed shot, it doesn't sound like honking though: https://www.youtube.com/watch?v=4d2LnoE ... e=youtu.be

Haha I was in a similar position when designing GOB. I almost went for a 72" barrel!

Close - I measured it a while ago and it was something like 5".

Missed a few shots today...
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Re: Good ol' Boomer - damage pics and videos

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