SpudFiles

I have already built one air cannon, but it is rather bulky, hard to transport, and the air reservoir takes waaaayyy too long to fill.

For my Second air cannon, I decided to use a two liter soda bottle for an air reservoir. I found that a half inch PVC pipe fit nicely in the neck of the bottle, but then I ran into a problem...How am I going to glue the PVC pipe to the bottle? I used PVC cement at first (lots of it) and that seemed to work. On my first test, the joint leaked . I decided to put a little epoxy around the rim, to make it airtight. that seemed to work.

Now the big question...Is the two liter bottle going to blow off in my face when I pressurize?

I will probably never fill my cannon over 70 psi, and sitck closer to 50 psi most of the time.

What glue should I use to secure the PET plastic of the bottle to PVC?

Here's what my first attempt looks like.

The plastic used in soda bottles are very similar in chemical compound to PVC.. with that said PVC cement might work but it might not... a 2 part general plastic epoxy should be strong enough for the kinda pressures you will be using it for.

my suggestion would be some plumbing epoxy putty, i use it on everything now, it only cost 3.98 for a 5 inch long 1 inch thick stick.

I've used super glue and epoxy to attach soda bottles to half inch pvc and both work good, and I've tested the joints (over 100 in total, we use this setup with cannons for a kids camp) to 125 psi with no failures.
And you just have to glue to like you would a normal pvc fitting.

I've used the smaller bottles, and have bonded the 1/2 inch piping with the coke bottle with 5 min epoxy. Holds really well

I concur. epoxy holds really well for this.

You can buy an adaptor for the typical soda bottle thread from Spudcom.com, Two-Liter Pop Manifold [P-500]

The best thing to do is sand down the threads on the bottle and then epoxy it into the ball valve.

jimmy101 wrote:You can buy an adaptor for the typical soda bottle thread from Spudcom.com, Two-Liter Pop Manifold [P-500]

I know this is old, but is there any such thing available on the market now? Need something thats easy screw on and off between NTP/ NPT (US) and / or BSP (UK) Standard Pipe threads AND typical Soda Water PET bottles with standard PCO 28 threading

http://imajeenyus.com/mechanical/201205 ... ndex.shtml

It's fairly easy to make your own adapter using epoxy casting, I had done that with this BBMG project

Often people just drill a hole in a cap and add a nipple with nuts (and washers) on each side of the cap.


A 3D print file at https://www.thingiverse.com/thing:878942 soda bottle to 1/4" NPT


Another 3D printed one, this one from the water rocket community
https://www.youtube.com/watch?v=xHOR-srdI_k

Thanks for responding. Yes, I did find the 3D print models; currently looking at local 3D prints that may be affordable in material/ strenght I want.

I was wondering if there are any of those old types available or made by anyone? Or long gone?

xbliss wrote:Or long gone?

Looks like it. What pressures are you looking to run at?

jackssmirkingrevenge wrote:

xbliss wrote:Or long gone?

Looks like it. What pressures are you looking to run at?

Using it for a non gun purpose where I MUST HAVE "Screw on and off" capability while holding water without leaks.

The 3D prints seem a a bit tough due to 3DHub saying PLA prints might have issues with threads. Might have to go for more expensive SLS or other print.

Would be great to have an off the shelf item that used to do this. Why doesnt it exist when so many DIY projects now use PET bottles?

Why doesnt it exist when so many DIY projects now use PET bottles?

That's a very good question and just off the top of my head. One could take a cap from each and glue them together back to back and mount them in tubing then drill the center out. Or if you have the equipment to machine a adapter from a stick of Delrin or alike...