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Posted: Sat Dec 06, 2008 6:19 pm
by daccel
I was thinking about how to avoid having to get the burst disk holder custom machined, and came up with this. Still requires some work, but could be done yourself.

It consists of a hex bushing, a socket set screw and a nipple. The left side of the bushing is drilled and tapped to fit the set screw. The set screw is drilled out to accept the barrel, with the socket acting as a guide for this. The nipple to hold the projectile is threaded into the right side.

The socket would have to be equal or larger than the barrel so that it could still be used to insert and remove the screw.

The available sizes of set screws may limit this too much, and I haven't used a tap before so I'm not sure how difficult that part would be, but there must be a way to modify existing parts to create something more compact than a union.

Posted: Sat Dec 06, 2008 7:36 pm
by jackssmirkingrevenge
Interesting thoughts :)

I'm looking forward to getting some further testing done on this when I'm back home, though it seems I'm going to have quite a hectic schedule.

Posted: Sat Feb 28, 2009 12:38 pm
by THUNDERLORD
Since I got my bike tire co2 filler, (And noticed 3000PSI air tanks for paintball), I've been a little obsessed with Burst-disk cartridges myself.

The advantages seem to be the compactness and simplicity.
While the quick opening speed adds benefit to compactness also since they are more effective than other valves in short barrelled designs.

Also for a compact captive bolt or shooting knife blade.... or captive bolt 1/3 of knife blade that shoots open,longer on impact :roll: :twisted:

I've been thinking of a booster stage for rockets where the burst-disk could be contained in the nose cone final stage also...

I was also thinking of a large design, something like a pre pressurized plastic 16 or 20 ounce plastic drink bottle, pre-charged through a shrader, and incased in a cartridge.
The end of an air gun, co2 pistol or PB gun could be threaded for the shrader...
It could be screwed into the barrel and the pressure of the shot would simply pass through the shrader pin, bursting the cartridge.
Metal pipe would be used of course...

Also the compactness would make them useful for air-cane design...

ETC. (like I stated I've become quite obsessed with them lately) :wink: 8)
Thanks again JSR! :)

Anything new on them or you're working on something else now?

Posted: Sat Feb 28, 2009 4:18 pm
by daccel
As an update to my burst disk holder idea above, I wasn't able to drill out a set screw. It was too hard, and dulled the bit right away.

The solution I found was to use flare fittings. But I think the angle may weaken the burst disk, so more layers or thicker material may be required.

Posted: Sun Mar 01, 2009 12:08 pm
by MRR
Has someone ever thought of building a cartridge with a mini coax piston?

Image

When you place a tiny equalization hole in the piston and a light spring behind it, it's like a check valve and you can fill it from the front (red arrow).

Now all you need is a hammer / spike that hits the burst disk in the rear (green) to pilot the piston.

Posted: Sun Mar 01, 2009 12:37 pm
by jackssmirkingrevenge
MRR wrote:Has someone ever thought of building a cartridge with a mini coax piston?
Take a look ;)

Posted: Sun Mar 01, 2009 12:46 pm
by MRR
Nice, you already did. 8)

I had this idea for building a mortar. Dropping the cartridge into a pipe with a nail on the ground.

But i guess your new design has more flow....

Posted: Mon Mar 02, 2009 12:44 am
by jackssmirkingrevenge
MRR wrote:I had this idea for building a mortar. Dropping the cartridge into a pipe with a nail on the ground.
The Holman Projector - hitsory's first recorded spudgun - had a valve at the base of the barrel that was effectively a hammer valve where the projectile falling down the barrel was itself the hammer.

Posted: Mon Mar 02, 2009 11:49 am
by MRR
Damn, every time I think that I have a good idea someone else did it before :evil3: .

I also had an idea about a gas operating ammo feed but a dead guy named "Browning" :wink: already did that.

Posted: Mon Mar 02, 2009 2:09 pm
by jackssmirkingrevenge
That's why it pays off to research, even mechanisms that might not directly be related to spudding - humanity has been at this "inventing" business for millenia now, chances are someone already came up with a useful solution and no point in reinventing the wheel.

Posted: Mon Mar 02, 2009 2:24 pm
by THUNDERLORD
@JSR, Seems like your pengun/design itself could be modified into BD cartridge pretty easily, but mass producing them (?)....

I was trying to think of a way (fill valve???) to charge high pressure cartridges using dry ice from a tank Maybe hundreds or thousands could be filled quickly,economically(?)...

BTW, I forgot to mention another advantage of the BD cartridge is that the tank or chamber used to burst the cart.s can be kept further away like a belt, backpack, coatsleeve(?) and still have good performance.

Also that for cloud/vortex design, a large BD design could be added (think m-203 mount on m-16) with a small ball- valve, the Large burst-disc could be selected, or close/open valves for the cloud/vortex action, using the same handle (air source and trigger).
Sure would be cool if someone tried that IMO.
(I don't have the time or interest in clouds myself to build everything I'd like to right now) :(
:wink: 8)

Posted: Tue Mar 03, 2009 12:57 am
by jackssmirkingrevenge
I actually tried attaching the pengun to a 0.177 barrel to see if it would work as a cartridge, the BB came out at considerable speed but not the sort of power I was after.

Still, it was around 300 psi, might be a different story at say 1,000 psi though, I'm still looking for that scrapped fridge :roll:

Posted: Tue Mar 03, 2009 8:05 pm
by THUNDERLORD
...Still, it was around 300 psi, might be a different story at say 1,000 psi though, I'm still looking for that scrapped fridge :roll:
Just after I got off-line yesterday, an idea hit me regarding mass filling Burst-disc cartridges ,OR even refilling co2 cartridges (refillable modified 12 gram or even 88 gram, especially 88 gram with the adapter)...

I thought, why not insert hundreds at a time into a large pressure vessel (homemade... or better large modded pressure tank)...

Then hook that vessel to another full of warming dry ice or store bought helium or nitrogen (connected to a regulator)...

When the pressure is inserted into the vessel containing the cartridges, the check valve (whatever one way valve) would be forced open and the pressure inside would be slightly less than the pressure applied (due to pressure necessary to open the check valves)...

Then the extra pressure from the chamber containing the cart.s (gas between the spaces not occupied by cart.s) could be relieved into another vessel and stored for whatever...

once the pressure is relieved completely the cartridges could be removed and loaded for use or something...Any thoughts on that ? :wink: 8)

Posted: Tue Mar 03, 2009 11:12 pm
by jackssmirkingrevenge
I had thought up something similar before, the problem is the larger pressure vessels get, the harder it is to find strong ones.

Posted: Wed Mar 11, 2009 2:59 pm
by THUNDERLORD
jackssmirkingrevenge wrote:I had thought up something similar before, the problem is the larger pressure vessels get, the harder it is to find strong ones.
Maybe a modified scuba tank, or large tank like for helium or welding.
Seems like maybe thousands would fit at a time!
Some thought would be needed to modify one though since it could get...Dangerous.

Since I've been thinking of bursting pre-charged discs by adding more pressure, the concept of liquid storage (gas) has occurred to me.

For example, if a pressurized gas (stored in gas form) is transfered into the same size vessel, seems like both would have HALF the pressure as the original. Also the pressure will drop rapidly as it's released.

But when the gas is stored as liquid (CO2, Propane, ETC., the same pressure, But MORE volume than the storage tank can be removed, right(?).

I do see one advantage to storing as gas though, that it doesn't need as much barrel length to vaporize from liquid to gas.
IIRC, one reason pistol co2 guns have lower velocity because the liquid co2 needs barrel length to vaporize (expanding), and the liquid has less volume. So sometimes adding only one inch to co2 pistol barrel length will yield a 100fps or so increase (?) IIRC from reading somewhere...

BTW, Geez, I'd like to connect a 3000 psi air for PB into a dummy CO2 in the handle of a CO2 pistol and see...Perhaps I'll call it a crossman 357 "Magnum" instead if just cros. 357 (or maybe just... BOOM!)IDK... :twisted: :D 8)