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Here we are with our raw materials. A box of Plaster of Paris from our local Home Depot, and a empty 20 oz. Dr. Pepper bottle. Yes, you can use almost any brand to your taste. |
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If you're afraid of Plaster of Paris, then don't click on the picture on the left. |
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I'm cutting off the bottom of the Dr. Pepper bottle to be used to help mould the top of our FTC mould. |
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Here, I'm cutting off a short section of FTC to use as the center mould. About 6 to 8 inches. |
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This section will fit inside of the bottle and we'll pour the Plaster of Paris into it. |
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Here's another look at the FTC tube perched inside of the bottle with the cutout bottom. |
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Use some petroleum jelly as a release agent on the FTC tube section. |
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Use some petroleum jelly on the bottle as well. I reached in through the top and smeared it around the top. Replace the cap. |
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What to use to mix the plaster of paris? Why a 2 liter bottle of course. You can use the bottom for mixing. The top makes a good funnel. |
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I've got some water in a (spare) bottle and I mix per the directions. |
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Nicely mixed. Don't get any Plaster of Paris on your skin. It truly can cause burns. |
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The top of the 2 liter bottle makes an excellent funnel to pour the Plaster of Paris into the short FTC tube. |
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I've poured in the plaster of paris. I used some electricians tape to keep the FTC tube in the center straight. In subsequent attempts, I poured sand into the gap between the bottle and the FTC tube. The sand helped keep the tube straight and also kept the Plaster of Paris from leaking out the tiny gaps. |
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Here you can see the Plaster of Paris that has filled up the FTC and the throat of the 20 oz. bottle. |
| Here's another look at the bottle and FTC setup. |
| 24 hours later, it is all set up. I then take my utility knife and cut away the bottle. |
| Here's a closer look at what is left of the bottle, with the FTC tube and the Plaster of Paris as our mould. |
| I've started to cut away all of the plastic using a Dremmel. You can see the track that the Dremmel left by its cutter. |
| I cut more and more of these tracks around the outside of the mould, trying to get the plastic from the bottle off the throat of the mould. |
| After much cutting and long labor, you can see that I've got the plastic off. Unfortunately, for this mould, the throat broke as well. I should have been more patient with it. |
| Another look at the mould. |
| In other moulds, the throat remained which is preferable. If heating the plastic of the bottle, you don't want its throat contracting from the heat. |
| I have my Plaster of Paris mould and my Wagner heat gun. In this picture, I'm cutting the bottom off of a 20 oz. bottle. |
| With the label removed, I've slipped the bottle over our FTC mould. |
| When the bottle is heated up, the plastic starts to contract. I've got to be careful to evenly heat the bottle so that it contracts all of the way down to the size of the FTC mould. |
| Slowly the plastic will contract and shrink down to the size of the mould. |
| ... more heating ... |
| ... more heating ... |
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The plastic wants to bend all which way. Heat it as evenly as possible to get it to shrink as evenly as possible. |
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We're getting pretty close here to having the bottle being the size of the FTC mould. |
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Don't let the plastic cool or it will harden, making it harder to get it to shrink again. |
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We're really close now. It's almost to size. |
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Getting closer. |
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Here I am with the bottle almost to size. I did better on subsequent tries to get it to size. You can see the bottle just barely fits over the FTC tube. Cut away some of the bottom of the shrinked bottle which may have flared out. In a subsequent page (someday!) I'll show how to glue on the bottles to the FTC itself, and getting one step closer to building a FTC Water Rocket. |
