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cup shaped bursk disk
Posted: Sat Jan 19, 2013 10:26 am
by jean
ok im thinking
of a cup shaped burst disk machined out of delrin or something
or made by deep drawing with vacuum out of some sort thermoplastic
-allows a quick change
-act as a check valve
-act as sabot
what do you think about this?
jean
Posted: Sat Jan 19, 2013 4:17 pm
by MRR
The cup piston has to be much wider than the barrel or it doesn't work. In this configuration it has to travel back the entire length of the cup to reveal the barrel.
I actually don't know what you try to achieve with a cup shaped burst disk.
Posted: Sat Jan 19, 2013 5:09 pm
by jean
hi MRR
it is a little difficult to describe for me...
both pic are burst disks!!
the idea is a burst disk that is
-easy to change
-can act as a ceck valve
-no oring
-no glue
-no leaks
-up to high pressure
-can act as a sabot
think about a cartrige like this
Posted: Sat Jan 19, 2013 5:32 pm
by MRR
ok im thinking
of a cup shaped piston/burst disk machined out of delrin or something
or made by deep drawing with vacuum out of some sort thermoplastic
Ok, I get it now, the OP was a little misleading though (I had a piston hybrid in mind).
...
Wouldn't machined burst disks be too expensive if you used them regularly? Vacuum shaped burst disk on the other hand should work nicely.
I think I know what you are trying to achieve with this design (read BTBs pump post) and I think it is not worth the effort.
Posted: Sat Jan 19, 2013 5:35 pm
by jean
thanks for you reply (edit ist now)
and here the idea
Posted: Sat Jan 19, 2013 10:28 pm
by jackssmirkingrevenge
It would be a little annoying to machine in quantity, and since you're still having to use a threaded fitting to replace it you might as well be using a normal burst disk...
Posted: Sun Jan 20, 2013 2:05 am
by jean
machine this would be annoying but with vacuum forming .. may for a low quantity of shotgun style cartridges (sabot)
how do you fill the cartridge with a normal bursk disk and wouldnt it leak at real high pressure?
o-ringed plug and bolts instead of threaded plug...
jean
and here the first try with vacuum forming
Posted: Mon Mar 04, 2013 5:47 am
by Labtecpower
and here the first try with vacuum forming
That looks pretty good!
What kind of plastic did you use on this one?
It may be easy to seal this kind of burst disks with an O-ring put in a slot in the barrel..
Posted: Mon Mar 04, 2013 8:17 am
by jackssmirkingrevenge
Not at all bad... the problem of still needing a threaded connection to be able to fit it still negates the advantage though in my book.
Posted: Mon Mar 04, 2013 11:23 am
by mobile chernobyl
sacrificial obturating ring FTW
Calculate shear forces and utilize a material with well known material properties.
That's my goal when I start on the semi-auto hybrid at least!
(Graduating in 3 months!)
Posted: Mon Mar 04, 2013 12:21 pm
by jackssmirkingrevenge
mobile chernobyl wrote:That's my goal when I start on the semi-auto hybrid at least!
Cartridges?
Posted: Mon Mar 04, 2013 12:57 pm
by jean
hi
why not a closed foam rubber..no need for an o ring...
@jack the idea to drop an cartridge in a pump to fill it isnt bad. with this sort of burst disk a filling valve isnt needed.
i only need an locking mech for the idea i mentioned further and the ignition seems an problem... i use a spark gap instead of the nichrome-wire but it wont ignite.
anyway im a bit busi today...
jean
edit the plastic i use was from a salad..
Posted: Mon Mar 04, 2013 7:13 pm
by mobile chernobyl
jackssmirkingrevenge wrote:
Cartridges?
Silly cartridges... they certainly don't utilize the biggest advantage of a combustion gas gun - gaseous propellant!