Splicing 2L bottles

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rockets-in-brighton
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Splicing 2L bottles

Post by rockets-in-brighton »

The better weather is encouraging me to open the box which contains my collection of bottles awaiting conversion into rocket engines and recovery contraptions.

Apologies in advance as this question is a bit parochial, mainly for UK members: I'm using typical 2L bottles, the kind commonly used for lemonade, flimsy PET with flat parallel sides and rounded tops.

I'd like to make symmetrical splices which require a sleeve made from a bottle with a slightly larger diameter than the main pair. So, are there any brands that you know of with a diameter slightly greater than 9cm that could be shrunk down to make a suitable sleeve.

I'm assuming this is going to be easier than trying to use an internal sleeve, as that seems to be only appropriate for these thicker continental bottles that have 1mm walls. However if anyone has successfully converted that technique for flimsy PET bottles I'd be interested to hear how it worked out.

Anyway, any tips gratefully accepted!
Cheers
Steve
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Brian
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Re: Splicing 2L bottles

Post by Brian »

the way ive been splicing is with no seperate sleve at all. you get 2 bottles, cut off the bottoms, clean them, then you get some hot water (i microwave water for 5 minutes) and stick half of 1 bottle in the water till it shrinks a bit and then glue them together.
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Re: Splicing 2L bottles

Post by Andromeda »

Brian wrote:the way ive been splicing is with no seperate sleve at all. you get 2 bottles, cut off the bottoms, clean them, then you get some hot water (i microwave water for 5 minutes) and stick half of 1 bottle in the water till it shrinks a bit and then glue them together.
Sometimes you can find two different brands which have bottles that slip over each other and form a "stove-pipe" type joint. But shrinking them a bit with hot water is a great idea too. I will remember that one. Thanks a ton!
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Re: Splicing 2L bottles

Post by rockets-in-brighton »

For the moment I'm going ahead using 1L bottles, and harvesting the sleeve from a 2L. Getting the usual problems of uneven shrinking and wrinkles in the sleeve, but I guess with practice it will improve.

This is why I was following the US Water Rocket blog with interest, to see if there are any good tips on shrinking and splicing. I think my ideal would probably be using 2L 90mm diameter bottles shrunk down to about 85mm, so that making large volume rockets doesn't require too many splices.

I'm wondering now if wooden formers would work as well as the metal cylinders USWR used.
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Re: Splicing 2L bottles

Post by Tim Chen »

rockets-in-brighton wrote:For the moment I'm going ahead using 1L bottles, and harvesting the sleeve from a 2L. Getting the usual problems of uneven shrinking and wrinkles in the sleeve, but I guess with practice it will improve.

This is why I was following the US Water Rocket blog with interest, to see if there are any good tips on shrinking and splicing. I think my ideal would probably be using 2L 90mm diameter bottles shrunk down to about 85mm, so that making large volume rockets doesn't require too many splices.

I'm wondering now if wooden formers would work as well as the metal cylinders USWR used.
I have seen other people who had a lot of success just using a bottle of the desired diameter and filled with cold water for use as a form for shrinking. The cold water keeps the form bottle from shrinking but the sleeve bottle only shrinks until it hits the form bottle.
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rockets-in-brighton
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Re: Splicing 2L bottles

Post by rockets-in-brighton »

Tim Chen wrote:
rockets-in-brighton wrote:For the moment I'm going ahead using 1L bottles, and harvesting the sleeve from a 2L. Getting the usual problems of uneven shrinking and wrinkles in the sleeve, but I guess with practice it will improve.

This is why I was following the US Water Rocket blog with interest, to see if there are any good tips on shrinking and splicing. I think my ideal would probably be using 2L 90mm diameter bottles shrunk down to about 85mm, so that making large volume rockets doesn't require too many splices.

I'm wondering now if wooden formers would work as well as the metal cylinders USWR used.
I have seen other people who had a lot of success just using a bottle of the desired diameter and filled with cold water for use as a form for shrinking. The cold water keeps the form bottle from shrinking but the sleeve bottle only shrinks until it hits the form bottle.
That's exactly the method I was trying this morning. I think the amount of heat required to take a 95mm (3 3/4") diameter sleeve down to 82mm (3 1/4") diameter makes uneven shrinking pretty much unavoidable, at least in my amateur hands.

Also annoying that the process trashes the bottle used as a former if the heat is splashed about carelessly - again, my experience this morning.

(just realised I said 90mm ainstead of 95mm bove, is there an option to edit posts somewhere?)
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Re: Splicing 2L bottles

Post by rockets-in-brighton »

Brian wrote:the way ive been splicing is with no seperate sleve at all. you get 2 bottles, cut off the bottoms, clean them, then you get some hot water (i microwave water for 5 minutes) and stick half of 1 bottle in the water till it shrinks a bit and then glue them together.
Out of interest, what sort of bottle do you use and what pressure can these splices hold?
Cheers
Steve
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Re: Splicing 2L bottles

Post by Spaceman Spiff »

rockets-in-brighton wrote:
Tim Chen wrote:
rockets-in-brighton wrote:For the moment I'm going ahead using 1L bottles, and harvesting the sleeve from a 2L. Getting the usual problems of uneven shrinking and wrinkles in the sleeve, but I guess with practice it will improve.

This is why I was following the US Water Rocket blog with interest, to see if there are any good tips on shrinking and splicing. I think my ideal would probably be using 2L 90mm diameter bottles shrunk down to about 85mm, so that making large volume rockets doesn't require too many splices.

I'm wondering now if wooden formers would work as well as the metal cylinders USWR used.
I have seen other people who had a lot of success just using a bottle of the desired diameter and filled with cold water for use as a form for shrinking. The cold water keeps the form bottle from shrinking but the sleeve bottle only shrinks until it hits the form bottle.
That's exactly the method I was trying this morning. I think the amount of heat required to take a 95mm (3 3/4") diameter sleeve down to 82mm (3 1/4") diameter makes uneven shrinking pretty much unavoidable, at least in my amateur hands.

Also annoying that the process trashes the bottle used as a former if the heat is splashed about carelessly - again, my experience this morning.

(just realised I said 90mm ainstead of 95mm bove, is there an option to edit posts somewhere?)

I have had similar results. Shrinking too much is unpredictable.

I just did an experiment based on Batkiter's design and I had some good luck. I filled a bottle with hot water. I don't know what the temperature was but it was as hot as I could get to come out of the faucet after running it out a minute or two. Whatever my hot water heater puts out I would assume. Then I put it on a launcher and put about 10PSI into it and let it cool off. When I cut the bottle open it was expanded into a very nice sleeve that fits perfectly over an unexpanded bottle.
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Re: Splicing 2L bottles

Post by rockets-in-brighton »

Spaceman Spiff wrote: I just did an experiment based on Batkiter's design and I had some good luck. I filled a bottle with hot water. I don't know what the temperature was but it was as hot as I could get to come out of the faucet after running it out a minute or two. Whatever my hot water heater puts out I would assume. Then I put it on a launcher and put about 10PSI into it and let it cool off. When I cut the bottle open it was expanded into a very nice sleeve that fits perfectly over an unexpanded bottle.
Ooh! well done! Just what I was going to try next, on the grounds that it should make for a smooth sleeve. So you just left it to cool; roughly how long?
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Re: Splicing 2L bottles

Post by Brian »

rockets-in-brighton wrote:
Brian wrote:the way ive been splicing is with no seperate sleve at all. you get 2 bottles, cut off the bottoms, clean them, then you get some hot water (i microwave water for 5 minutes) and stick half of 1 bottle in the water till it shrinks a bit and then glue them together.
Out of interest, what sort of bottle do you use and what pressure can these splices hold?
i have spliced 2L, 1.25L and 300ml strait sided (cylindrical) bottles and my pump only goes up to 120psi and the splices had no leaks and i use vise glue.
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Re: Splicing 2L bottles

Post by rockets-in-brighton »

Brian wrote:
Out of interest, what sort of bottle do you use and what pressure can these splices hold?

i have spliced 2L, 1.25L and 300ml strait sided (cylindrical) bottles and my pump only goes up to 120psi and the splices had no leaks and i use vise glue.
Brilliant! Thanks for that.
Cheers
Steve
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Re: Splicing 2L bottles

Post by dongfang »

Hi,

If you cut the whole bottom off one bottle, but leave part of the top on another, you can usually squeeze the top into the end where the bottom was. I have done this a lot. You have to practice a little to find out where to stop before the inner bottle folds/collapses.
I got lazier now, and I leave the whole top on the bottles - I just burn some extra holes in the bottle shoulder, to allow better passage.

In here, the green 2l bottle have a 0.00001 % or something like that larger diameter than the clear ones. I have sometimes modified my technique,and cut top and bottom off the green bottles to make joiner sleeves, and then left both top and bottom on the clear bottles (with holes burned of course).

I never had any luck with heat treatment - but OK i did not try very hard. That reminds me that I am going to build a computer controlled oven for soldering - maybe I could make an alternative program for shrinking bottles?

Regards
Soren
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Re: Splicing 2L bottles

Post by rockets-in-brighton »

[UK only, I think]

While rummaging around in the back of the loft this weekend, I dicovered a stash of the thick-walled 500ml bottles I used to use, with the labels still attached. They have been rebranded, but the original supplier is Hildon, and they have a website listing their PET bottle range: http://www.hildon.com/pet.php.

The interesting thing here is that in addition to the 500ml bottles they also supply 750ml and 1L bottles - and I would assume that these are also thick-walled PET bottles.

The 1L is actually for still water rather than sparkling, but I have 500ml bottles for both kinds and I can't tell the difference between them without the labels and caps.

I'm going to be cheeky and ask them for a sample 1L.
rockets-in-brighton wrote:The better weather is encouraging me to open the box which contains my collection of bottles awaiting conversion into rocket engines and recovery contraptions.

Apologies in advance as this question is a bit parochial, mainly for UK members: I'm using typical 2L bottles, the kind commonly used for lemonade, flimsy PET with flat parallel sides and rounded tops.

I'd like to make symmetrical splices which require a sleeve made from a bottle with a slightly larger diameter than the main pair. So, are there any brands that you know of with a diameter slightly greater than 9cm that could be shrunk down to make a suitable sleeve.

I'm assuming this is going to be easier than trying to use an internal sleeve, as that seems to be only appropriate for these thicker continental bottles that have 1mm walls. However if anyone has successfully converted that technique for flimsy PET bottles I'd be interested to hear how it worked out.

Anyway, any tips gratefully accepted!
Cheers
Steve
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Re: Splicing 2L bottles

Post by CH20Rockets »

my way of splicing is getting 3 2L bottles 2 with their cap ends and 1 for the sleeve. All you need to do is shrink the bottles (not the sleeve) slightly smaller than the bottle. Thats what I do. My 5.25L crashed and its splice still works well.

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Re: Splicing 2L bottles

Post by U.S. Water Rockets1 »

CH20Rockets wrote:my way of splicing is getting 3 2L bottles 2 with their cap ends and 1 for the sleeve. All you need to do is shrink the bottles (not the sleeve) slightly smaller than the bottle. Thats what I do. My 5.25L crashed and its splice still works well.

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As long as you don't try and push the pressure envelope, the splices should outlast the bottles. Typically the bottles will get creased in a crash or from handling and the splices are thicker and stronger and resist physical damage.
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