By Lindsay Wilson
A powerful gun which fires spuds can be made easily from 15mm copper plumbing pipe. Here’s how!
Parts List:
1. Inside each of the reducing couplings there is a ridge against which the 15mm pipe normally sits. File this ridge off so the 15mm pipe slides easily through the coupling.
2. Cut a 72cm length of the 22mm pipe, and a 92cm length of the 15mm pipe. Cover both threads of one of the 15-22 couplings with PTFE tape. This gives a better seal.
3. Attach the coupling to one end of the 72cm 22mm pipe and crimp it on. Slide the 15mm pipe through the coupling so that 5cm of it protrudes. Crimp the coupling on to the 15mm pipe. This is the muzzle end of the barrel.
4. Slide the 22mm (all round) T-piece on to the other end of the 22mm pipe and crimp it on. Cut a 5cm length of 22mm pipe and crimp it on the opposite end to the larger length of pipe. The 15mm pipe will now extend right through the T-piece.
5. Crimp the other 22-15 reducer on to the short piece of 22mm pipe so the 15mm internal pipe extends by about 2.5 cm. Make sure you have filed off the rim inside the coupling! The main barrel is now complete.
6. Crimp the valve on to the barrel (the end closer to the T-piece), noting which way the arrow on the valve points. It should point towards the muzzle end of the barrel.
7. Cut a 5cm length of 15mm pipe and crimp it on to the other end of the valve. Crimp one of the elbow joints on to this as well.
8. Cut a 6.5cm length of 15mm pipe and crimp it on to the other end of the elbow joint. Crimp the other elbow joint on to this pipe.
9. Crimp a 7cm length of 22mm pipe on to the vacant hole in the 22mm T-piece attached to the barrel. Crimp the 22-15-22 T on to this pipe so that the 15mm hole on the T faces the 15mm hole in the opposite elbow joint.
10. Cut a 16cm length of 15mm pipe and crimp it between the 22-15-22 T and the 15mm elbow. Some of the nuts may have to be loosened to make room to do this!
11. Crimp a 5.5cm length of 22mm pipe to the other hole on the 22-15-22 T.
12. Drill a hole large enough to take the bicycle valve in the centre of the 22mm endcap. Pass the valve through this hole and tighten the nut to hold the valve in place. A seal is formed by the rubber disc left on the valve after it has been cut out of the tyre.
13. Crimp the 22mm endcap (with valve in place) to the short length of 22mm pipe mentioned in step 11.
We’re all ready to go!!
To fire:
1. Open the 15mm valve by turning the lever so it points along the barrel.
2. Push a spud down the muzzle end of the barrel while pressing on the tip of the bicycle valve to release air trapped behind the spud.
3. Close the 15mm valve.
4. Connect the bicycle pump to the valve and pump as hard as you can until you can’t pump any more. This fills the space between the 15mm and 22mm pipes with air at about 90 psi (5.6 bar)
5. To fire the gun, open the 15mm valve VERY QUICKLY. The spud comes flying out at about 60 mph! (I worked that out from timing how long it took to land after being fired-it rose to about 300 ft!).
Variations:
· Put Rice Crispies in the barrel on top of the spud.
· A stone on top of the spud.
· Carrots.
· Put one spud in, pour some petrol into the barrel and put another spud in. Fire this at a candle. (DON’T TRY THIS!!)
· Bananas-very messy!
· Almond nuts.
You can contact me at lrw42@supanet.com
Diagrams & pictures:
WARNING: EVEN THOUGH THIS IS A SPUD GUN
NEVER, EVER FIRE IT AT ANYBODY!!!!!
