Print PDF
Favorite
Email
Step 9Construction of the Piston Housing
Once your piston is done you need to make the piston housing.
Get your spare 50mm PVC tee and cut a piece of 50mm PVC pipe 7cm long. Solvent weld it to the socket end of the 50mm female threaded socket adapter and then solvent weld the adapter and pipe to one of the horizontal ports on the tee. If required sand out a small 'lip' inside the adapter to allow the piston to fit through.
Get two 50mm x 40mm PVC bushings and cut 1cm off the end of one of them. Cut a piece of 40mm PVC pipe 15cm long and solvent weld one of the bushings to the end and the other bushing just above the other. Then solvent weld the female socket adapter onto the bushing on the end of the pipe. One bushing should now be inside the adapter, and the other just above it.
Make sure the end of the pipe without the adapter on, is perfectly level. The piston is going to seal against this. It is absolutely necessary it is flat. Solvent weld the bushing that isn't inside the adapter to the opposite end of the tee that the first female adapter is welded too.
See the pictures for help.
The 15cm of 40mm pipe should now be half way inside the tee
Get your spare 50mm PVC tee and cut a piece of 50mm PVC pipe 7cm long. Solvent weld it to the socket end of the 50mm female threaded socket adapter and then solvent weld the adapter and pipe to one of the horizontal ports on the tee. If required sand out a small 'lip' inside the adapter to allow the piston to fit through.
Get two 50mm x 40mm PVC bushings and cut 1cm off the end of one of them. Cut a piece of 40mm PVC pipe 15cm long and solvent weld one of the bushings to the end and the other bushing just above the other. Then solvent weld the female socket adapter onto the bushing on the end of the pipe. One bushing should now be inside the adapter, and the other just above it.
Make sure the end of the pipe without the adapter on, is perfectly level. The piston is going to seal against this. It is absolutely necessary it is flat. Solvent weld the bushing that isn't inside the adapter to the opposite end of the tee that the first female adapter is welded too.
See the pictures for help.
The 15cm of 40mm pipe should now be half way inside the tee
| « Previous Step | Download PDFView All Steps | Next Step » |
could you perhaps elaborate further on:
1) when cutting the bushing, which end are you cutting? The 50mm or the 40mm end?
2) Is the modified bushing the one that goes on top of the other or is it the other way around?
Also could you also provide a picture of the bushings together before the female adapter is attached?
-Thank you
2) From the pictures I'm assuming the modified bushing goes on top as you can see the cut marks on the bushing in this photo:
http://www.instructables.com/files/deriv/FYP/S0JT/FGXS2K1C/FYPS0JTFGXS2K1C.MEDIUM.jpg
Sorry, built this gun almost 2 years ago. Don't have any other pictures of it.
From what I remember:
You have the 50mm female adapter. This has female 50mm threads at one end and a socket at the other. The unmodded 50x40mm bushing goes inside this (make sure the end of the bushing with the "lip" is the closest to the threads ofthe female adapter once glued inside it.
Then cut 1cm off the other bushing at the end which has the "lip". Now you want a piece 15cm long piece of 40mm pipe. Glue this pipe in to the unmodded bushing that is inside the adapter, once glue inside that, glue the modded bushing to the 40mm pipe so it sits above the bushing you just glued that is inside the adapter.
Only thing I changed with this was a breech lock. Basically I just drilled a hole through the 1.5" adapter that the 1.5" barrel slides in to, then I put a bolt through this hole. Then at one end of the 1.5" barrel I dremeled two "L paths" opposite each other that are the width of the bolt. So to lock the barrel in, you line up the two "L paths" with the bolt, push the barrel in and then twist it to lock. Sort of like any bolt action lock on a rifle.
Changes I would make, perhaps cut down on the chamber volume. The whole chamber volume in the stock isn't required at all. But apart from that, it was a pretty cool gun. I still use it from time to time as you can see by the recent video I posted the other week.
recently i was surfing the web for PVC fittings and i stumbled upon these:
pvcfittings.com/graphics/7ways.jpg
my first thought when i saw these was "revolver!".
you could have 6-7 projectiles ready to go with some kind of O-Rings on the end of each port to seal and you got a spudgun in revolver/grenade launcher style.
Plans shouldn't be followed step by step, it is good to do it yourself. Though when you do it yourself you do make some mistakes, like with my first piston valved cannon, but that leaves room for improvement.
When making this gun i just build it bit by bit, thinking out every step. Although the construction of the piston housing may seem complicated, it's just something I came up with on the spot when I thought "how do I make this go in to this while still having this work" when I realised I couldn't get the fitting I wanted (50mm female adapter with spigot fitting, meaning it would fit inside the tee instead of this one which is the same diameter as the tee so I had to use those bushing fittings).
Anyway goodluck, be sure to post some photos when you finish.
so my discovery is that the inner core of a golf ball will fit perfectly inside of a 1.5in PVC pipe (sch40). this could be very helpful for any one who cant get their hands on some SDR 21 pipe or 40mm pipe.
Thanks
and then you cut off the air pressure by closing the valve, and the piston moves back to where it was before? How does that happen?
Force behind the piston, and force in front. Since there's a larger surface area on the back of the piston, than the front of the piston, the piston is pushed against the barrel. remove the force behind the piston, and the forward force pushes the piston back.