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A water rocket is a type of model rocket using water as its reaction mass. The pressure vessel (the engine of the rocket) is constructed from thin plastic or other non metallic materials (usually a used plastic soft drink bottle) weighing 1,500 grams or less. The water is forced out by compressed air. It is an example of Newton's third law of motion.

Bottle Rocket Caps

Discussion about Compressors, hose, pipes, fittings, launchers, release mechanisms, and launch tubes.
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1964deano
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Bottle Rocket Caps

Post by 1964deano » Wed Sep 15, 2010 5:27 am

Hi all Love this website...
Just wanted to know what bottle caps you use if you use them in your design. I use a modified gardenia quick release. The probelm is that it prevents the cap from screwing all the way down. Thus I am in need of a cap that is 5mm longer (has more thread).
Are these available anywhere? Love to get some!!

thanks

Dean :D



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rockets-in-brighton
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Re: Bottle Rocket Caps

Post by rockets-in-brighton » Wed Sep 15, 2010 5:43 am

1964deano wrote:Hi all Love this website...
Just wanted to know what bottle caps you use if you use them in your design. I use a modified gardenia quick release. The probelm is that it prevents the cap from screwing all the way down. Thus I am in need of a cap that is 5mm longer (has more thread).
Are these available anywhere? Love to get some!!
Obviously it will depend on what is available in your part of the world, but check out the useful air.command tutorial on making nozzles where they mention the problem and one possible solution: the caps from liquid soap dispensers - in Australia these have a compatible thread but they are longer.


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Steve
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1964deano
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Re: Bottle Rocket Caps

Post by 1964deano » Wed Sep 15, 2010 7:10 am

thanks for that..I was hoping to find a manufacturer to make some for me... Any ideas..?
Dean.



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rockets-in-brighton
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Re: Bottle Rocket Caps

Post by rockets-in-brighton » Wed Sep 15, 2010 1:38 pm

1964deano wrote:thanks for that..I was hoping to find a manufacturer to make some for me... Any ideas..?
If you have the right budget you can get anything you like made to order but I suspect that the budget for custom bottle caps in small batches would be higher than you'd like.

Alternatives: you can find an existing cap (see the tutorial referenced above); you could make your own threaded* cap from scratch on a lathe; you could try something along these lines to create a thread in a suitable material without using a lathe: http://bbs.homeshopmachinist.net/showthread.php?t=43645; you could forget threads and use an adhesive instead.

*Somewhere around here is a post about PET bottle thread pitches, be warned that there is variation between countries.


Cheers
Steve
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WEB: http://groups.google.co.uk/group/rockets-in-brighton

1964deano
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Re: Bottle Rocket Caps

Post by 1964deano » Thu Sep 16, 2010 12:02 am

Hi
I have access to lathes CNC machines etc....but a tripple start thread takes some know how.....

Dean.



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Re: Bottle Rocket Caps

Post by air.command » Thu Sep 16, 2010 1:12 am

1964deano wrote:Hi
I have access to lathes CNC machines etc....but a tripple start thread takes some know how.....

Dean.
Curious... What kind of bottles are you connecting the nozzles to? Tripple start threads are not very common. How many of the caps were you after?

- George


http://www.AirCommandRockets.com

1964deano
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Re: Bottle Rocket Caps

Post by 1964deano » Thu Sep 16, 2010 4:59 am

I thought that coke etc bottle are tripple start ? Prephaps I am mistaken. I would like to have 50ish..



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Re: Bottle Rocket Caps

Post by air.command » Thu Sep 16, 2010 7:25 am

1964deano wrote:I thought that coke etc bottle are tripple start ? Prephaps I am mistaken. I would like to have 50ish..
The regular caps are just single threaded. The thread is often interrupted making it look like multiple threads. The interruptions are there so that the bottle can release pressure without the cap flying off as you unscrew it.

I am not sure what the minimum quantity is but you may want to try these guys they have a big range:
http://www.capsandclosures.com.au/products-caps02.htm

- George


http://www.AirCommandRockets.com

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U.S. Water Rockets1
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Re: Bottle Rocket Caps

Post by U.S. Water Rockets1 » Sat Sep 18, 2010 10:52 pm

1964deano wrote:I thought that coke etc bottle are tripple start ? Prephaps I am mistaken. I would like to have 50ish..
In the US the small (20oz and less) coke bottles (usually from vending machines but also in 6-packs) use a smaller thread and a different cap. The 2 liter bottles have a cap that resembles the smaller bottle cap, but they have a standard thread. Nobody has explained this yet.


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