How to make a 2L Reinforced Bottle

We are trialing using 2L reinforced bottles to power the rocket car. Here is a brief overview of our process.

We start with 3 bottles

- 1 x 2L bottle
– 2 x 2.25L bottles (although 2L would probably suffice)

Start with 3 bottles

The 2 x 2.25L bottles are cut so that one will go over over the bottom of the 2L bottle and one will go over the top. There is an amount of overlap as well where the top and bottom sections overlap to be 3 layers thick.

Cut out sections + 2L Bottle

Close up of the 2 cut sections

The next step is to shrink slightly the 2L bottle. A big pot is required which can be filled to a depth of 3/4 of the bottle + have spare volume so no hot water splashes out when the bottle is inserted. Be careful of this, make sure the pot is big enough.

Bring the pot of water up to about 75 degrees, you can test this by quickly inserting the bottle 2 seconds or so and see if it shrinks slightly. Dont get the water too hot or the bottle will shrink to fast and deform. Once the water is the correct temperate insert the bottle for 2  seconds and check how much the bottle shrinks. Its better to do it a few times rather than have the bottle too long in the water and deform.

Submerge the bottle to past 1/2 way until the bottom section shrinks, then turn the bottle around and do the top as well. Be very careful with the top, you dont want the spout deforming.  What you should end up with is a bottle that is slightly smaller over the entire area (except the bottle throat and cap section).

The next step is to fit the other two sections. Start with the bottom section first, you will find that as its a close fit it wont slide on easily due to the air trapped in the bottom section.  There are a couple of ways around this. One is to use a wooden skewer or similar and push it between the two bottles so the air trapped in the cutout bottom section can get out, or you can drill a small hole in the base of the bottom cutout (not the 2L) bottle and air will get out this way. As we are going to fit a Robinson coupling anyway this hole wont weaken the second bottle.

You can put a bit of PL premium between the two bottoms of the bottles to hold them together but this is optional.

Once the bottom section is on, put the top section over the top of the 2L bottle, we slide the top section underneath the overlapping bottom section. TO do this its easier if you have a wooden skewer and run it around the bottle while you push the top section in, then just push until the top section is in place. You will find that once in place they really dont move. You can add a strapping of fibre reinforced tape if you wish.

Here is a pic of the bottle when finished. Its has already had a robinson coupling added to it.

Completed Reinforced Bottle - Robinson coupling added

If you look carefully you can see the slightly shrunken inner bottle.

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This entry was posted on Saturday, June 26th, 2010 at 9:20 pm and is filed under Development. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.


One Response to “How to make a 2L Reinforced Bottle”

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