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"In the world of spuds today"

A place to ask general spud cannon related questions.
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Unread postAuthor: DYI » Mon Mar 10, 2008 8:59 pm

its cool but how could you use up 4" pipe like that, it could be a high pressure pneumatic that could archive supersonic, only use an fire extinguisher or a used tank or a pvc tank which is fairly safe


-new tank, the current one is part of the hybrid in my sig and weighs twice as much as it needs to because of the rather thick endcaps


I have as much 4" seamless steel pipe available as I want, I get it free from the metalworking room at school, and can get endplates welded on for about $5 by the local welder, with tapped threads and everything. The SCTBDC's 2" ID chamber is bigger than this particular piece, and I don't quite trust the welds at 500 psi constant pressure, considering that the guy who did them doesn't have a certification to weld on pressure vessels.

The hybrid in my sig will definitely be supersonic, even with relatively heavy ammo.

EDIT: 3tables, PVC tanks aren't exactly safe at 300 psi, just FYI :wink:
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Unread postAuthor: Novacastrian » Tue Mar 11, 2008 12:25 am

"In the world of spuds today" I made a piston with integral sealing face and a endcap with integral bumper. The size of the piston is 98mm.

Image
Image
Image
The bumper still has to be drilled (in the center) for piloting.
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Unread postAuthor: jackssmirkingrevenge » Tue Mar 11, 2008 12:34 am

Looking extremely good Nova :) though a little dainty, perhaps some radial ribs between the spool ends would welp support it on impact with the bumper.

The size of the piston is 98mm


That's just shy of 4 inches, what ungodly beast is this component for?
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Unread postAuthor: Gippeto » Tue Mar 11, 2008 12:42 am

Very nice! That sucker is going to "boogaloo" (accelerate very quickly) when you trigger it.

I'm curious though, why not put your "floating" o-ring on the rear portion of the piston?

And, are you casting urethane now?
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Unread postAuthor: Novacastrian » Tue Mar 11, 2008 12:49 am

jackssmirkingrevenge wrote:
The size of the piston is 98mm

That's just shy of 4 inches, what ungodly beast is this component for?


Well it's simply for a multi purpose cannon, something that can shoot stuff up to 33.7mm, down to 12.7mm :D
The chamber is 304 stainless approx 200mm long, walls are around 2mm thick. Max piston travel will be 8.5mm
The major hassle is modifying certain details of the barrels (to make them efficent, i will have to alter their length in the chamber to adjust piston travel and sleeve them as to get rid of dead space) as the design involves putting a barrel "stub" into the chamber witch will be a piece of the largest dia barrel i will be using.
Should be good with the larger barrel up to ~300psi. Not that i plan on using it at that pressure- normal shop pressures should be enough.

Edit: Sorry Gippeto i missed your post, i have been casting poly for quite some time now. It's bloody awesome gear.
Different hardnesses, from soft as a pencil eraser to hard as nylon, the bumper is 40a duro (pencil eraser) and the sealing face is slighty softer than bone 90a duro (95 is hard as bone).
As for the hammer piston i decided to keep it simple

@JSR i don't think it will need ribs but i will be the first to fess up if proven otherwise! Thanks for calling it "Dainty" too Prick :D :wink:
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Last edited by Novacastrian on Tue Mar 11, 2008 12:59 am, edited 2 times in total.
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Unread postAuthor: SpudBlaster15 » Tue Mar 11, 2008 12:56 am

DYI, why do you have 27 soda cans sitting on that desk? Appears to be a similar scenario to what is currently occurring in my bedroom, where I have *counts* 12 empty soda cans sitting on my desk. :lol: Sadly, that case was purchased on Saturday. :roll: I really should be fat, but my metabolism is almost as good as Rag's. Unfortunately, I don't believe I have his indestructibility. :D
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Unread postAuthor: MrCrowley » Tue Mar 11, 2008 1:10 am

Novacastrian wrote:Well it's simply for a multi purpose cannon, something that can shoot stuff up to 33.7mm, down to 12.7mm :D

You must be mistaken, golf balls are 44.5mm in diameter :wink: :D
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Unread postAuthor: Novacastrian » Tue Mar 11, 2008 1:25 am

MrCrowley wrote:
Novacastrian wrote:Well it's simply for a multi purpose cannon, something that can shoot stuff up to 33.7mm, down to 12.7mm :D

You must be mistaken, golf balls are 44.5mm in diameter :wink: :D


JSR has a fetish for Epoxy, I have a fetish with smaller calibers 8)
It is much easier for me to get away with smaller stuff here. I could make a golf ball barrel to fit but i would be relying on 33.7mm porting :shock: :D

Edit: Gippeto i misunderstood your previous comment about my "floating" o'ring. I was just about to ask why it would be better, until i realised that it would be because i would lower the pilot volume, however when the piston hits the bumper it should seal, negating that fact somewhat. Thanx for opening my eyes :)
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Last edited by Novacastrian on Tue Mar 11, 2008 1:32 am, edited 1 time in total.
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Unread postAuthor: jackssmirkingrevenge » Tue Mar 11, 2008 1:32 am

Well it's simply for a multi purpose cannon, something that can shoot stuff up to 33.7mm, down to 12.7mm


Ooh, now that's something to look forward to :D The 40mm PVC pipe I use for chambers has the same inner diamter, interesting.

As for the hammer piston i decided to keep it simple


I think he meant having the o-ring as check valve rather than incorporating a hammer piston.

Thanks for calling it "Dainty" too


That's exactly what it is, ya big poofter :D what's the final colour scheme going to be?

Image

:D
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Unread postAuthor: Novacastrian » Tue Mar 11, 2008 1:34 am

jackssmirkingrevenge wrote:
Thanks for calling it "Dainty" too

That's exactly what it is, ya big poofter :D what's the final colour scheme going to be?
Image
:D


You made my afternoon with that comment :D Biatch
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Unread postAuthor: jackssmirkingrevenge » Tue Mar 11, 2008 2:11 am

I'm sure you'll counter it with a host of very manly damage pictures eventually, do we have an estimated time of completion for this one?

The chamber is 304 stainless approx 200mm long


One thing, why so short? Since you're using shop pressures, I'd go for at least half a metre of chamber length.
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Unread postAuthor: Novacastrian » Tue Mar 11, 2008 2:19 am

As would i, however i use the "scraps" :P The time of completion for this will be by the end of the week, fingers crossed, about another 3 hours.

Keep in mind that my total expenditure over all of my cannons and ammo would not have exceeded $150Aus :twisted: :P :? :shock: :) :( :o :lol: :roll:

Edit: Just realised that if i take into account the fact that i am on the clock at work i have probably "earned" about $2000 dollars making my cannons.
Hope PCGuy doesn't see this :roll:
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Unread postAuthor: MrCrowley » Tue Mar 11, 2008 2:23 am

Novacastrian wrote:Keep in mind that my total expenditure over all of my cannons and ammo would not have exceeded $150Aus :twisted: :P :? :shock: :) :( :o :lol: :roll:

Times that by 15 :(

Bloody addictive and bloody expensive.
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Unread postAuthor: jackssmirkingrevenge » Tue Mar 11, 2008 2:26 am

MrCrowley wrote:Bloody addictive and bloody expensive.


I spend a lot on airguns, but not spudguns. The amount you save by casting your own fittings is substantial, for example why purchase a pressure-rated endcap when you can make your own with a cardboard disk and a pouring of epoxy that costs you less than $1?
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Unread postAuthor: MrCrowley » Tue Mar 11, 2008 2:38 am

jackssmirkingrevenge wrote:
MrCrowley wrote:Bloody addictive and bloody expensive.


I spend a lot on airguns, but not spudguns. The amount you save by casting your own fittings is substantial, for example why purchase a pressure-rated endcap when you can make your own with a cardboard disk and a pouring of epoxy that costs you less than $1?

Because I like pissing $13.27NZD up the wall everytime my holesaw comes a bit loose and makes a hole too big in the end cap. :roll:
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