SpudFiles

So my first gun was quite alright, but after thinking it over, i have 5 screws in a single plane of the chamber, which makes me a little afraid to use it as that creates a point for rupture.

NOTE:regardless of what it looks like, the ratios are based on 8th grade math, if you want my formulas, they are (c1Rsqr*pi*c1l)+(c2Rsqr*pi*c2l):(bRsqr*pi*bl) where b is barrel, and c1 is the forward portion of chamber, c2 is the larger aft portion of chamber, as you can see by the math the ratios are based on cubic inches... Rsqr is radius squared.

DIMENSIONS: B24"Lx2"W C6"Lx3"W+12"Lx4"W C:B 1.38:1
Made with pressure rated Water supply ABS rigid core, rated to over 180psi, cost a good little bit, and nearly ruined tungsten carbide dremel bits(there is no black paint on it) dwv nazis back off

EDIT: I now have several barrels that can be swapped out, a longer 2"(I have a 10' piece im gonna cut either 6'/4' or 3'/7'), the original, and a 1.5"x2'

In this new design improvements include: larger chamber; all wiring hidden (i used a dremel to cut a grove in one of the coupling edges and sealed the wire in); a 1 inch piece of 1.5 inch pipe attached at 4 points in the aft end of the barrel to aid in barrel stuffing; new grip design; forward grip uses finger adjustable tabs to allow for side handle reconfigurations; all screws/penetrations are in couplings to give better structural integrity; a piezo-electric trigger built into the handle which is actually small enough to hold. ohh and the report is way louder due to the the new 1.38:1 C:B ratio, no reduced accuracy either

NEW AMMO! 2" fish bobbers with the trim shaved (dremel) and filled with anything sealed off with electrical tape. I used tempura paint, sand, or lead weights. there is also some cool stuff you can do with them, but thanks to a very helpful person, ive since removed that information and the bobbers do not split until impact, filling them with paint makes basketball size or larger marks on anything it hits, like a jumbo paint ball, i do however completely wrap them in electrical tape, two layers leaves less than 1/64" of space all around so the tight fit gives a perfect shot, also i have a ramming rod with a foam ball on the end, i cover it with vasaline, and like gay porn it relieves all friction allowing for just enough back pressure as well as extraordinary side seal, leaving a tape streamer removes the aerial beach ball effect by creating a little drag which allows long distance shots, ive never hit a target larger than a basketball from more than 130' which is an easy hit as i achieve a good high velocity.

EDIT: beginning to add components for measured propane, starting with the fan. I spent about 25$US at radio shack, on the fan, light up switch, and 12v(8AA) battery pack. I also added a male threaded piece to the old barrel, with just enough clearance to still attach the forward handle, i have also made a new barrel which is 1 1/2"x2' barrel (I will make a longer one, as this makes my C:B almost 5:1) and of course i attached a coupling to the original barrel.

assembly: the battery pack fits neatly away inside the front handle, and the switch is cleanly installed in an easy to flick position in the "trigger" spot of the forward handle. the batteries are easily removed via a 9v connector. the fan will sit directly behind the spark gap, and the wiring has eyelets on both the fan and switch ends, which allows me to attach them with a bolt threaded through the chambers aft coupling... this also allows easy removal. I thought i was just buying a regular fan, but it has LEDs(see pic) which I think will light up the smoke as i clears the chamber... just a nice perk

the propane metering system is being built now!

Nice gun, like the paint job alot .Sweet amo too nothing like a little homeade pyro technics.

Read the rules buddy.
Discussion of solid propellants, explosive devices or incendiary projectiles fired specifically from a spud cannon is prohibited, and may result in a permanent banning of your account.

Interesting ammo though.

Does the fishing bob split when fired?

Pretty nifty combustion you have there. You've done a good job on some build details. Even though the paint job was a little half hearted, it actually works in a sort-of artsy way.

You could help out your performance with a longer barrel, you would of course sacrifice portability some.

Also the DWV police here will eventually have something to add regarding your design....

Welcome to Spudfiles! Nice effort overall. You obviously did some homework before building it.

You got DWV which isnt complete suicide on a spray and pray but use pressure rated parts next time. But other than that its pretty nice.
and the ratio looks larger than 1.38:1, looks more like 4:1

Edit: starman i think you can see the future, I guess your post was submitted while i was writing mine

thank you, honestly, i did very little homework, other than material research. i really try to use common sense when i build, i was halfway through with my first when i realized the flawed design and the risk of parting at the multiple entry points. i also sanded all joints that i applied cement to to roughen them up so a better bond may be made, soon all add a pic of some of the finer points, like the 12/6 oclock ignition points, as well as the inner barrel guard, and the paint job looks awesome in real life, the photos don do it justice, there are some amazing little marbled details to it that just look crappy in photo...

bigbob12345 wrote:You got DWV which isnt complete suicide on a spray and pray but use pressure rated parts next time. But other than that its pretty nice.
and the ratio looks larger than 1.38:1, looks more like 4:1

Edit: starman i think you can see the future, I guess your post was submitted while i was writing mine

Indeed BigBob.. What would we do without you...

I guess I am the unofficial DWV police now, maybe I should ask pcguy to change my name to the DWV police

Looks like a fun combustion. Cool paint job too.
If you keep shooting that tree it's gonna be polka dotted!!!
Just wondered what you're going to name it? 8)

I like the form factor and I wish mine were as portable (that will be the next one). I agree with bigbob that the C:B ratio looks more like 3:1 or maybe more... I would guess it makes a pretty big bang, like you said. Love the fishing bobber ammo idea! Nice handle placement, too.

using d_hall's program, it warns my barrel is too long, so if it were 3:1 i somehow doubt that result would come about...

Nice job man, some good progress for a second cannon. Any plans to go bigger with more sparks and propane?

I'm actually planning on chopping the barrel about 3 inches from the reducer, and connecting a female threaded piece. then having several interchangeable barrels. i have also found a source for 1 3/4" propane tanks for camp gear, which i think will be much more aesthetically pleasing to have mounted on the chamber, and with a measuring system as well. no plans for more sparks, but Im strongly considering a chamber fan, i want to keep the design as simple as possible, and having more sparks will require a more complicated triggering system, and i like my simple push button igniter, it gets the job done and doesn't require batteries

well sorry forum police for double posting, but I wanted to draw some attention to the new features ive added, to hopefully get some feedback/suggestions, and to add that my thought yesterday (last post) has mostly been implemented, just propane system to add now, gonna need a separate chamber just to get a good 4% mix, otherwise ill have to have a ton of piping... what if i thread metal fittings into some better rated PVC, then going back to metal to thread into the chamber?

That was very informative, nice

I like the paintjob too.