My First Piston Valve Launcher

[acs2997]

i actually have already watched that one! thanks a ton though, ive looked all over youtube as well as this website. i think i have all the info and instructions ill need. theres only two more thing i was wondering about: how long does it take for the air to travel through the hole in the piston and into the chamber? and can i just use a female and male adapter behind the piston? is there a need for all those screws?

[MrCrowley]

Well unless you're using o-rings, don't put a hole in your piston. There will be adequate space around the outside even though it may not seem like that. Your chamber should fill normally, the piston isn't much of an obstruction to the air.

[acs2997]

and the need for the screws?

[mattyzip77]

Thats just one way of doing it. you can use a female adapter and a mip x fip threaded bushing.

[MrCrowley]

Yes, it would be better to use male and female adapters rather than screws which may weaken the structural properties of the PVC. Make sure to find the socket type of female threaded adapter which requires a piece of pipe to attach it to the tee. This means the piston can be housed inside this piece of pipe and can be removed by unthreading the male adapter. There are some female threaded adapters which will prevent this as their inside diameter constricts at a certain point inside the fitting; preventing the piston from being removed.

The ones I'm talking about are like this:

[mattyzip77]

And one of these which is a mip x fip threaded bushing


http://www.plumbingsupply.com/images/pv ... sxfips.jpg

[Technician1002]

May I suggest using a really good bumper with PVC? Trust me on that one. I found ABS does better in that department. Use the proper glue to attach ABS to PVC. I eventually retired that cannon and built one entirely from ABS using the same piston.

[MrCrowley]

I've had the same thing happen when I forgot to re-insert the bumper in my PVC piston cannon as well. Half a tennis ball will usually work well for a couple dozen shots.

[acs2997]

so you dont reccomend aq half tennis ball?

[MrCrowley]

Half a tennis ball will usually work well for a couple dozen shots.

In other words, use a tennis ball hemisphere and make sure to check it every few dozen shots for signs of wear, deformation, cracks or failure.

[Technician1002]

I recommend dense open cell foam rubber.

The current bumper is just behind the golf ball for the ABS cannon. This works well.