SpudFiles

This is my first cannon, the BigD . Despite its looks its actually quite ergonomic! I made it within 24 hours of finding this site, actual construction time was about 4 hours (24hrs includes sleep and planning ). It shoots @ 100psi and i estimate that it will launch a marble almost 2 football fields (correct me if this seems wrong). I plan to attach a portable hand pump to the air chamber and paint it black. The gun in total cost me about $60. So any ideas for improvement ? Any input is much appreciated!


W/ super fail grip lol

W/ minor upgrades, may i stress minor!





About the caps, they do not have a rating but there is a reason i bought them, they are made for underground plumbing. Underground plumbing needs to be tough stuff so i figure its good enough for my cannon

Just attach your jpg files on the edit page, or just point to the image with the direct link and wrap it with the "img" tags...like this...



Not a bad cannon. Really short barrel...it's hurting your performance a lot.

Welcome to Spudfiles!

Holy chamber, batman!

Ok. Not bad, especially not bad given the 24hr bit.

Really short barrel...it's hurting your performance a lot.

Ditto on that one. A longer barrel will really "wake up" the performance.

Closer to 1:1 will be a better ratio for barrel and chamber.


Welcome.

Very nice work. I agree with Starman if the barrel was longer it would perform better.

thnx for quick responses! I will add a larger barrel asap .

There you go! You've gotten the pic posting thing down. Now take care not to double post, meaning don't post one after the other....just edit your last post if you are the last poster.

BTW, those chamber end caps look suspiciously like SD rated PVC...a big no-no, especially in the pneumatic world, and pressures in the 100 psi range.

What the hell did you glue that with? Looks good though. I applaud you for looking around here for ideas rather than asking for plans.

Nice first cannon.Get a longer barrel and your performance will sky rocket.Are those endcaps pressure rated? They don't look like it.

jonnyboy wrote:Are those endcaps pressure rated? They don't look like it.

That was my thought as well.

But I would have to agree with everyone else. This is pretty nice. I am impressed that you did build this within 24 hours of finding this site. This shows me that (1) you already have experience or (2) you know how to use the search.

Either way, welcome to Spudfiles. I look forward to seeing more stuff from you.

@ pvsarsenal, i just used pvc cement

About the endcaps, I don't see a psi or kpa rating so they prob. are not but i intend not to take this over 100 psi and it was fine @ 150psi

As for previous exprience, i have none. I made a gun out of a keg tap and thats what got me started w/ these guns.

Thanks for the input and my mom works for an landscaping company that does irragation so i should be able to get the parts on the cheap 8)

SaggingBaggage wrote:@ pvsarsenal, i just used pvc cement

About the endcaps, I don't see a psi or kpa rating so they prob. are not but i intend not to take this over 100 psi and it was fine @ 150psi

As for previous exprience, i have none. I made a gun out of a keg tap and thats what got me started w/ these guns.

Thanks for the input and my mom works for an landscaping company that does irragation so i should be able to get the parts on the cheap 8)

Did you use primer as well?

No primer and use of DWV parts makes this cannon very unsafe. I've had pressure rated parts fail at half the rating before, so I wouldn't take this thing close to 100PSI. It may work a few times, but most likely it will fail eventually at those pressures. Just because it can take 150PSI once doesn't mean it can always take it.

I'd stick under 75PSI if I were you.

@ozzy yeah i did use primer

And I couldn't help to notice you have a sprinkler valve...

Edit: I realize this is a couple days old and some people might have a problem with that, but I wanted to make a point about the caps to a newbie.

Looks good for a first gun, especially given only 24 hours since first seeing the site!

I doubt the caps are pressure rated for one reason. The stress distribution in a flat surface like that isn't ideal. Most caps are curved because it reduces the maximum stress in them (at least from my understanding of it). You don't see square pipe for pressure for the same reason--it's much weaker for the same wall thickness.

With that being said, I have seen flat caps before, but I can't recall any in sizes larger than 2 inches.

Do the caps have NSF-PW printed on them? If so, they are pressure rated. If not then I would look to replace the air chamber, which is all that should be necessary for safety from what you've said.

As others have mentioned, a longer barrel will improve your power dramatically. If you want to retain the same length, reduce the pressure chamber size, which probably is a good idea if you intend to use a bike pump for pressure.

If I were you, I'd get rid of that pipe nipple, and replace it with regular PVC pipe and a male coupler. That will allow you to have a longer barrel.