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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: Novacastrian » Tue Feb 19, 2008 2:16 am

If you are going to be working with plastic only simple high speed steel works a treat.
Anyway it's great to hear i may have a machining competitor in the future. :D If you decide to get a lathe and you need any help i have around 10 years experience. :wink:
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When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

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Unread postAuthor: jackssmirkingrevenge » Tue Feb 19, 2008 2:20 am

Novacastrian wrote:If you decide to get a lathe and you need any help i have around 10 years experience.


I'll be sure to seek your advice before parting with my hard-earned :)
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Unread postAuthor: Novacastrian » Tue Feb 19, 2008 8:27 pm

In news today the hammer piston that i made for my .50cal pneumatic performs very well. I can't tell how many fps the improvement is, however a work collegue has tried the cannon with the new piston and seems to think is has improved quite a bit.

Even if i am only getting an extra 20fps i'm happy, as it goes towards removing the drop in performance caused by my breech being like 8" from the start of the barrel.

I also finished making a 6mm piston coax today, it works surprisingly well and propels a .177 lead slug at around the same speed as my old break barrel springer, (probably around 550fps) at 110psi.
It is designed the same as the Double Shot and as such can be pumped to high pressures, i can see it doing some nice damage at say 250-300psi.

I have also started work another hammer piston coax, the piston size will be just under 2" and it will feature a cler polycarbonate chamber-just so the newbies can understand how these particular cannons work, animations can only show you so much! :D
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Unread postAuthor: DYI » Tue Feb 19, 2008 9:31 pm

Today I got the [redacted] back from the welder for the prototype of the [redacted] project. I've pressure tested it, along with my valve, up to 50 psi so far, at which point it seals near-bubbletight. Considering that it will only need to be airtight at [redacted], I think this is a good start. It has been holding at 50 psi for more than 1 hour now, with ABSOLUTELY NO detectable pressure drop on the gauges.

GGDT also tells me that the new full 2" porting SCTBDC valve will work better with 50ci of dead space than with 20ci, so here it is (it hasn't actually been taped and sealed yet, as I'm preparing for a ski trip and have little time):
Image
The ball valve handle at the top is pointing in the direction of the desired flow through the valve. I discovered today that the male side of unions seals better than the female side, so I guess I've been wasting considerable money and effort on the old version, when I could have just turned both unions around :roll:
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Unread postAuthor: OuchProgramme » Tue Feb 19, 2008 9:45 pm

Currently: Thinking of some possible ideas for a future semi-auto.

I have an idea, i'll try to make a prototype soon.

I'll post it later
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Unread postAuthor: LikimysCrotchus5 » Tue Feb 19, 2008 10:29 pm

Wait DYI, its that to make your cannon a triggered burst disk cannon? What is that new piece for?

What does [redacted] mean?
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Unread postAuthor: Carlman » Tue Feb 19, 2008 10:57 pm

LikimysCrotchus5 wrote:Wait DYI, its that to make your cannon a triggered burst disk cannon? What is that new piece for?

What does [redacted] mean?


its the new valve for the SCTBDC

he chose to put [redacted] in the place of something he did not want us to know the name of
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Unread postAuthor: bigbob12345 » Tue Feb 19, 2008 11:18 pm

Im excited for this [redacted] project I wonder what it is :?

I just finished testing my new PG(in pnuematic cannon showcase) it works like a charm.
It is my first perfectly sealing piston valve and is a very fun cannon to use.
Doing some work saving up some money for a new metal high pressure burst disk cannon 220ci(thats right bigger than the SCTBDC)2.5in bore 2in porting. I dont know if it will ever become a reality but it is nice to dream about :)
Its going to cost me a lot so the pg will probably be my last gun for a couple months.
Experemented with different types of burst disk that are eaisyer, cheaper and quicker to make than the aluminum foil ones with the KAMG.
No succsess so far.
Tryed to record hangtime of the KAMG at 200psi never saw or found the projectile :twisted:
And i discovered that the male side of the union seal better just as DYI did.
Well thats about it for me today.
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Unread postAuthor: SpudBlaster15 » Wed Feb 20, 2008 1:02 am

If the male section of steel unions sealed more effectively than their female counterpart when using aluminum soda cans as burst disks, it would have saved me a large amount of time and frustration. I suppose aluminum foil may be a different story, but who wants to mess with 16+ layers of foil to hold back nearly 800PSIG. The aluminum washer I machined on a lathe works wonders for all burst disk materials, including sheet metal.
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Unread postAuthor: jackssmirkingrevenge » Wed Feb 20, 2008 1:52 am

Novacastrian wrote:In news today the hammer piston that i made for my .50cal pneumatic performs very well. I can't tell how many fps the improvement is, however a work collegue has tried the cannon with the new piston and seems to think is has improved quite a bit.

Even if i am only getting an extra 20fps i'm happy, as it goes towards removing the drop in performance caused by my breech being like 8" from the start of the barrel.

I have also started work another hammer piston coax, the piston size will be just under 2" and it will feature a cler polycarbonate chamber-just so the newbies can understand how these particular cannons work, animations can only show you so much! :D


Good to hear :D perhaps you could line up some acrylic sheets and see which design penetrates the furthest? It would be good to calculate a rough percentage increase of performance over a normal piston design. Also, you need to get yourself a shock pump, without high pressures on small pneumatics you're missing out.

The clear cannon sounds like a brilliant idea, can't wait :D
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Unread postAuthor: DYI » Sat Feb 23, 2008 9:59 am

Liki, the SCTBDC always had a TBD valve. However, the porting used to be 1.5", and the new valve is 2" porting.

I just got back from my ski trip (which was f*cking awesome BTW), and there is still about 5 psi left in the [redacted] for the [redacted] project, after roughly 63 hours. At a leak rate of ~0.7psi/hour(which means I would lose less than .005 psi in the time it would be pressurised) , I'm reasonably sure that there won't be any major problems with [redacted], as there are still a few easy improvements I can make in sealing the valve.

Personally, I'd rather be using aluminum foil than sheet metal anyway; it's cheap, exceedingly simple to work with, and easily available at almost any grocery store. Unless test results are wildly different from what I expect (and testing the failure pressure for a 2" disk that bursts in the 400 psi range is a bit nervewracking), the new SCTBDC valve will use 2" disks 48 layers thick, which can be easily manufactured in bulk by simply starting with 3 layers and folding in half 4 times.

And bigbob, what do you plan on using as a pressure source for this 220ci high pressure cannon that you're thinking of building? Because I don't think I'd be able to afford to feed the SCTBDC without a job, at $2.70/shot for gas alone.
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Unread postAuthor: VH_man » Sat Feb 23, 2008 10:31 am

Well, i just came up with a great way to make a shell-fed system in my sleep last night... thats my news.

that and the Barret 14mm has gotten a serious bondo job. I will post it when im happy with the appearance, but it already looks sleek and sexy........
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Unread postAuthor: rcman50166 » Sat Feb 23, 2008 4:04 pm

I propose that any "article" posted starts with "In the world of spuds today" so that they are easily distinguishable from article comments? Sound good?
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Unread postAuthor: Novacastrian » Sat Feb 23, 2008 5:52 pm

"In the world of spuds today"
rcman50166 wrote:I propose that any "article" posted starts with "In the world of spuds today" so that they are easily distinguishable from article comments? Sound good?


That's better, hehe. :D
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In the world of spuds today.

Unread postAuthor: Ragnarok » Sat Feb 23, 2008 6:10 pm

@rcman: Sounds OK.

In the world of spuds today:

Nothing much. I've not done much building recently, and I want to change that, so I'm pulling the following projects off my drawing board for consideration:

- High pressure compressor.
This is a nice idea, but before I do this, I need to get everything on HEAL all kosher. I'm not using 30 bar in something that I haven't checked in minute detail.
To be honest, I've got a leak that appeared during the last set of modifications, and I can't quite nail it down at the moment, which isn't a good sign.

- Doing a coaxial advanced combustion for firing golf balls or spuds.
It's going to be a fair sight larger than what I normally build, but in terms of energy, actually surprisingly low - only the same as HEAL currently is, and a lot bigger in all dimensions.
Might go with MAPP to claim a little more power, as the local DIY often has it in stock - the extra cost of the gas will be incredibly small against ammo costs.

- Gauss pistol.
Relatively low energy of about 6 ft-lbs, but other features should make up for that. Semi-auto, 6mm projectiles, 20 round magazine, 20 rpm (600+ with mains charger), 4 or 5 stages, aiming for 10+% efficiency.
This one I like, but it's going to be fiddly.

I don't know which to go with. I like them all in their own way, but no single one is a perfect idea.
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