And lo the beast turned its hideous face unto meand unleashed its swift and horrible fury
Okay so the guts of this thing are really straightforward: it's basically a spud gun and there's a lot of instructables and other online resources that tell you how to make this so for mine I will be very brief and quite vague . . . this part of the instructable is not sufficient for a first timer to create a spud gun but should be enough for someone who's got a little experience.
- 2" PVC end cap
- two 2" PVC couplings
- a section of 2" PVC for attaching the above
- 2" to 3/4" PVC reducer
- 3/4 PVC nipple
- 3/4" Solenoid Automatic Sprinkler Valve
- 3/4" PVC Male to female threaded 90 degree elbow (both ends threaded)
- 3/4" PVC Male to female threaded 90 degree elbow (only male end threaded)
- 2 foot 3/4" PVC Pipe(longer is possible but I liked the look of the 2 footer)
- PVC primer and Cement (yes of course it has to be PVC cement not ABS)
- a roll of teflon tape
- brass 1/4" shraeder valve (home depot failed here but ace had this)
- Two brass 1/4" hose barbs (one end barbed the other threaded)
- A Blowgun (the compressor type not the Amazonian)
- small hose clamps
- 2' section of pressure rated 1/4" Inside Diameter Hose (Homedepot failed again but ace had this)
- a vise is useful for holding things still
- a hand saw
- Cresent wrenches the right size to turn the barbs and shraeder valve
- a tap set (optional but really useful)
- a drill and assorted bits
- screwdriver (though a screwgun is quicker)
Take your end cap, couplings, 2" pipe, and reducer and cement them together. Wrap the nipple in teflon tape and screw it into the reducer. Make sure the seams are as small as possible so that the compression chamber looks like a tank instead of a section of piping. Drill a hole near the top that goes through 2 layers of PVC and tap the hole for your shraeder valve. Wrap your valve in teflon tape and screw it in; the wrenches help a lot here.
While that's drying go ahead and unscrew the solenoid from your sprinkler valve, unscrew the top and open the valve up. Inside you'll see a rubber diaphragm. Off to one side of it you should see a little plastic spike with a hole in it. carefully remove the valve and take this spike out from the other side. If you're inquisitive like me go ahead and play around with the valve to make sure you fully understand how it works.
Now there's 2 types of valves out there: one type has a guide rod in the middle of the diaphragm and one does not. If yours does then you'll need to drill off to one side. Mine did not so now I drilled a hole through the middle of the top and tapped it for one of the barbs. Wrap a barb's threads in teflon tape and screw it into the hole with the wrench. Don't screw it in so far that it interferes with the diaphragm or you'll get a weird honking noise every time you fire it. I sorta liked this accidental honking so I left it in (see video). Now your sprinkler is modded. You can also buy a pre-modded one from a couple of online stores but where's the fun and learning in that!?
Take your modded valve and screw it onto the other end of the nipple (with teflon tape) making sure the arrows on the valve point FROM the tank TO the other side(barrel) screw your elbows together and into the other end of the valve and then insert your barrel. I had an iron sight from an airsoft sniper rifle but since the rifle has a scope I never put the sight on. I applied this now for aiming and coolnes' sake. Remember steampunk modding is all about found objects! But making a sight from scratch is possible too with a bit of effort.
The other barb goes into the back end of the blow gun(more teflon).
The NEXT DAY (pleas DO wait for your cement to dry completely) I put the hose onto my valve and blowgun to test the thing out and you can see the completed but unpainted assembly in the pictures.
If this is your first spud gun these instructions are certainly inadequate but fear not! Spudfiles has a good tutorial
on the valve mod with discussion and troubleshooting and this site has plenty of other tuts on the subject.
HOW IT WORKS:
If you're curious, the valve has 2 chambers in it . . .one above the diaphragm and one below. The diaphragm has a hole that lets both chambers share equal pressure and so the center of the diaphragm (held by a spring) presses on the outlet keeping it sealed. when the blowgun is released the pressure from the top half exits faster than the small hole in the diaphragm will allow the tank pressure through and so we end up with a massive pressure difference very quickly. this pulls the diaphragm up and the pressure exits through the previously blocked hole and out the barrel. this all happens faster than greased lightening and so much more energy is conserved than if you use a simple, slow ball valve. This conservation leads directly to superior performance.