Pneumatic Golfball Cannon- Shoots 450+ yards!

Step 8 Building the Piston

Okay now to build the piston.

There are two types that i'll show you how to make, a deodorant one and a plywood one. Either one will do.

Plywood Piston:
Find a hole saw with a diameter larger then 53mm but smaller then 58mm. Find some plywood sheet and use the hole saw to but out a few disks. I only needs 3 because the I used thick plywood but you made need more. I'd recommend a piston around 10cm long. So cut as many disks as you need to make that.

Once you've cut all your plywood disks, coat them with waterproof varnish and leave the varnish to soak in. When that's dry get a long bolt and put it through the middle of each disk (drill a hole if needed), tighten the nut at the other end so the disks are tight and can't move. If you have a drill press or lathe you can fix the piston with bolt to it and then sand it down as it spinds around.

If you don't you'll have do it manually with sand paper. I'd recommend making a deodorant can piston instead.

Anyway, sand the plywood piston down so it fits snug inside 50mm PVC pipe and you can push it with your finger. But make sure there is no room around the outside of the piston, the tighter fit the better. The bolt off cut a cricle of neoprene (rubber) the same diameter as the piston. You can usually find neoprene disks at HomkeDepot. This is your sealing face

Grab a metal washer that has a diameter small then 4.3cm but bigger then 3cm. Put your neoprene sealing face on one end of the piston and then the metal washer, put the boll through this and your piston then tighten the nut at the end. Just make sure to apply lube to your piston before using it and your done.

Deodorant piston
To make a piston for a 2" PVC tee all you need is:

*Deodorant can
*Neoprene rubber gasket(found in plumbing section, this is your sealing face)

• Suitable bumber

*Hot glue

Now cut the bottom 3" of your deodorant can, cut up some hot glue sticks, chuck 'em in there and melt them. Now your piston should be about 1/2 full with glue for reinforcement.

Drill a hole the size of your long bolt through the bottom of the can and through the glue, grab a washer that fits the bolt, put it on and then put your sealing face on the bolt with the washer on top.

Now thread the bolt through the hole in the cane and through the glue, it should come out on the other side, now find something thats soft and bouncy or rubbery as your bumper, this protects your tee from the piston breaking it when it fires back.

Put your bumper on the bolt and stick a washer on and then a nut, tighten the nut and thats your piston done.

In the picture below I had to seal the top of the sealing face because air leaked through the piston a bit.
The bottom of the piston in the picture is my bumper.

Comments

[pufferfish9108]

witch is better piston

[lucasman22]

with the deodorant can piston what brand did you use and what takes up the other half of the piston (other than glue).

[MrCrowley]

Can't remember, lynx maybe. I think I just used glue for half of the can, and then I used a hammer to whack down the ends of the can over the glue.

[monkeyboi309]

how the wooden piston seal? i don't get it

[MrCrowley]

With the rubber sealing face. Did you even bother to read the instructable?

[bob the builder #1]

thanks for the help on the piston.