QCTBDC: Something Different

Just build a cannon and want to show it off? Post it in here.

Postby sgort87 » Sun Jan 21, 2007 2:36 am

Thanks Dave, I'd be glad to share details on this. I doubt I'd ever put this up for sale. It's very dangerous with that broadhead and all... I can easily hook up a double-hand safety trigger circuit, but I don't want any potential trouble with that. I will put it up in my personal launcher gallery of the store though.

Tell ya what, I'll draw up a paint diagram of this in the morning. I'll also include an imporovement that I found after this prototype.

While you're at the cannon competition stuff, while you were away from the forums, my <a href="http://localhost/forums/viewtopic.php?t=14840">Mauler</a> was actually also nominated. :p

Thanks again DR.

I'll have some chrony details hopefully soon also.
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Postby DK » Sun Jan 21, 2007 3:49 am


I had to watch the video a few times to take in what i was seeing. I was honestly dumbfounded at the ingeneuity of your setup; it's darn clever!

I've already squirreled this video away for future reference. When you post up your paint diagram in the morning, you can rest assured that it will not go to waste. 8)

You never cease to amaze me Sean. =)

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Postby fullmetaljacket » Sun Jan 21, 2007 5:13 am

Impressive, particularly the extremely clean manner in which the burst disk is perforated, I like :D
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Postby markfh11q » Sun Jan 21, 2007 10:27 am

Very clever. I like the simplicity of the design: rather than pressure differentials to trigger a disk, let's use a broadhead and a pneumatic piston! Genius...

I'm also glad you didn't try and bother with the double-disk triggered design. I worked for a solid three days and couldn't get a little one I made to work. Just couldn't calibrate my burst material right. What are you using for burst disks? Looks like some sort of sheet aluminum or tin???
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Postby tim jones » Sun Jan 21, 2007 12:18 pm

Very impressive!

I'm a little confused about how you sealed the ram's penetrations on the pressure chamber, and how the air flows around the piston/broadhead. Your paint diagram will probably clear everything up.
tim jones
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Postby Navigator7 » Sun Jan 21, 2007 2:03 pm

Awesome, Gort!
Don't stop!!!!!
You got the gift.
America is full of greats doing what they do ....in their garage.
In ten years you'll have your own shop and walk around in a crisp white lab coat and smoke a pipe!

There is no doubt your system works.
My knowledge of pneumatics suggests something like this might gain just a little faster acting time and or increased air flow...as your poker thingy introduces a narrow spot bad for air flow.
<img src="http://i76.photobucket.com/albums/j18/Navigator7/Waterdawg/Gort_Stabber.jpg">
Essentially a razor hunting tip with the tip removed.

I don't see where a point helps your goal...which is the more the merrier.

I think your video is the best new development I have seen in years.
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Postby sgort87 » Sun Jan 21, 2007 2:14 pm

Hahah, thanks Nav! I'll have wear my lab coat in the next video. :p

What you modeled right there is EXACTLY what I am looking for. Since this was a prototype, I did not woory too much about the absolute best. I had originally planned for something with a more shallow tip and four blades. That would keep the disc popping faster and all at once rather than slowly popping over time. (As you saw, it was still a fast pop, but I think it could be better with this new broadhead type.)

Mark, the discs I use are aluminum from the sides of pop cans.

Paint diagram is almost finished.
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Postby Navigator7 » Sun Jan 21, 2007 2:25 pm

The name is too slow for your cannon.

How about?:

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Postby sgort87 » Sun Jan 21, 2007 3:25 pm

Okay, here's that picture I promised you.

<img src="http://www.spudfiles.com/uploader/uploadFiles/qctbdg.JPG">

I forgot the ball valve before the hose but that isn't all that important.

So the disc is inserted, "piston" is pushed up, and air gets turned on. The air pressure acting on the piston walls toward to barrel keep s the disc secured. Once the pressure builds, the 3 way is flipped and air rushes to the cylinder. The broadhead bursts through the disc and it blows out. Once the ball valve is turned back, the cylinder retracts and a new disc can be loaded.

The only flaw with this so far is that the type of cylinder used allows some leaking. It isn't enough to cause problems unless you are using a low flow air source. A better way of doing this is with a double-acting cylinder and a 4-way valve.
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Postby MX_ » Sun Jan 21, 2007 6:07 pm

Just an idea, but you could sell the lathed unions. Mainly because alot of people don't have access to a lathe, and then you won't have as much liability for selling it with the spearhead.

Plus then alot of other people could make this. Very ingenius I must say.
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