SpudFiles

Where did you get the 2.75" one Jack?

I showed a co-worker one my cannons, he brought it for me the next day saying I could have it as long as he say it flying through the air, apparently it used to be part of the ball race of a crane.

Second shot seemed much better, how does it feel working large scale?

Scary but oddly satisfying - never had anything against big launchers to be honest, it's the lack of space to take full advantage of their performance that puts me off.

the second shot is at maximum pressure as we used two disks instead of one - you can hear the filling valve open at 3 seconds, it takes a full 2 seconds to blow so I'm pretty sure the "chamber" was the highest it could go.

We were expecting better performance to be honest but with a barrel less than 4 feet long, 70 psi limit and 2" opening at the disk, all these factors were against us. We could go for a longer barrel, but the consensus is that things are getting a bit out of hand (especially after the window incident) so for the moment I doubt anything more powerful will be made.

Thats actually pretty impressive for such a heavy projectile and the use of relatively low pressure.

A powerfull cannon you have here! How does this frankenburstdisk work though? It opens after u fill it to a certain pressure? Cool that u made this from plumming parts, most ppl here use sprinkler valves.
I just saw the vids! Damn 1.4kgs flying really fast and then even nockin over a pellet! Impressive stuff. Yeah as u said this gun is getting outa hand lol. Asthough it always fun to try something new.

ant wrote:How does this frankenburstdisk work though?

Basically you open the red valve to fill the chamber, when it reaches a certain pressure the disk (usually a thin sheet of plastic) that is between the chamber and barrel will rupture and it fires. If you listen carefully in the second vid, there's a slight "whoosh" first as I open the fill valve, then it fires two seconds later.

The ammo you are using is not dissimilar from the shot put balls we used in athletics, dangerous things when given to idiots, and how i would have loved to witness a 3lb ball flying through the air, maybe you should make an epoxy
cast of it, and use the mould to cast say plaster, or even silicone would make for an interesting video, I can see it now : a 2.75" bouncy ball... I just had a flash back to half life, those fusion core things that fly around...or if you had serious time, a wax shell filled with flour or talcum powder.

Had the opportunity to run an 84 gram orange from this monster through the chrony this morning, bit of a rushed job so it wasn't at maximum performance but still managed a whopping 190 feet per second, that's just over 100 ft/lbs

Usually I would think that's a typo and you meant 1900 feet per second at just over 1000 ft/lbs

I'm sure it could go much higher, but when you're surrounded by thousands of litres of toxic and flammable solvents, 'tis best to err on the side of caution

You've worked on something bigger then 3/4" now!How does it feel?I love the look of one of those ball valves in those pictures it looks very ahhh um. . .shiny .

I think it would be a good thing to move that out of your work place if you intend to keep your job,that cement could of been pulverized by that large BB,and it makes me want to destroy things with mine now!

If it were up to me I'd be making 4" plus cannons, sadly I just don't have the space living in an urban area.

After the window incident things have been scaled back a lot at work, today's test was purely scientific