SpudFiles

The Polystyrene: http://en.wikipedia.org/wiki/Polystyrene

The solid poliestirene is a strong and light material, so, I decided to make some catridges for my pneumatic gun.

MATERIALS:

-Acetone:

It must be 100% pure




-Expanded polystyrene:

You can get it from boxes




Pipe:

It will be the mold for the plastic, so it must have the same diameter as your gun´s barrel. For example: 1".




- A container:

Caution: Do not use any plastic container! Use cristal or metal!





SAFETY:

The acetone may be dangerous:



Wear Gloves (latex) and if you can wear a mask.
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MAKING IT


1. Pour some acetone in the container.

2. Now, take the Expanded Polystyrene and break it in smaller pieces. Then, throw them in the container.

3. It will make small bubbles and the plastic will start dissolving. Help it pressing the plastic with a stick.

4. Continue throwing more plastic until the liquid becomes a dense mass.

5. Pour the mass in the pipe.

6. Leave it drying. It needs much time to get dry.



VIDEO:

The video isn´t mine!

[youtube][/youtube]

I´m spanish, so I can´t speak english very well. If any mods or admin see any error, please, correct it.

Very interesting, I'm guessing the final result is much harder than the expanded polystyrene you started off with.

I did this in a chemistry class forever ago.

Its a cheap method of making small plastic castings (Though technically a mold because it is plastic )

Still, great thinking by putting this towards spudding.

i wonder if some one could use this to mould a stock

when it melted and all can u touch it or will it burn you

I can see trouble happing a mile away with this. If another moderator or PCGUY want's to unlock this for more discussion so be it. Also I will PM PCGUY and ask if this should be open or not.

Welcome to Spudfiles euskalspud, lets try and stick to building spud guns.

After discussing this with jrrdw I am going to unlock this, since it is not that dangerous compared to other things done in science class nowdays.

isn't this napalm

roughboy wrote:isn't this napalm

This forum is on making plastic items by molding it.. We are pressing our luck straying offtopic. Let's not get the moderators too upset please.

I think you can Google the other subject, but it shouldn't be open for discussion here.

As long as we are on the subject of molding plastic;
HDPE softens when melted to a melted cheese consistency. It doesn't cast well at all. It doesn't gravity flow into small corners and the high coefficient of expansion makes huge voids as it cools and shrinks.

yes it is but we normally use gasoline.

As for molding the plastic, can't you apply pressure to the dissolved product to remove air and voids as it hardens?

I wonder how much this stuff shrinks as the acetone evaporates? If you were able to get 90% by weight plastic in 10% by weight acetone then it'll shrink roughly 10% as it cures (dries).

Like JSR said, the density must go way up and you probably need a pretty big volume of the expanded polystyrene starting material to get a casting. I believe you can get 4'x8'x2" sheets at a decent hardware store.

Still, an interesting idea. The contraction might actually be an advantage. If you cast a piston in a fitting then you might get just the right amount of shrinkage to give a correctly undersized piston for the fitting.

Actually, it should do that on it's own as the acetone evaporates away. In lieu of pure acetone, nail polish remover will work too (it's mostly acetone)

another idea would be to get rolls of acetate sheet and use that instead of polystyrene. end product would be much denser.

BTW, even when dry, you shouldn't expose the end product to an open flame, it will combust in a violent fashion (ever try lighting a guitar pick on fire? I don't advise it)

Actually, it should do that on it's own as the acetone evaporates away. In lieu of pure acetone, nail polish remover will work too (it's mostly acetone)

No, it doesn´t work. I tried to do whit that and it didn´t work. My acetone is 100% pure, i think it is used to remove some kind of glue (my dad used it).

As for molding the plastic, can't you apply pressure to the dissolved product to remove air and voids as it hardens?

The plastic industries do that, but i don´t know hoy much pressure is needed.


When its dry (REALLY DRY) you can light it and it burns like another plastic (slowly), and it doesn`t combust. But i dont recommend it.

So does this change the material, or just compact it?

Well stryrofoam is really nothing but buuble of air, or other gasses, trapped inside a thin wall of plastic, polystyrine, when the aceton comes into play it simply dissolved the plastic and the air just goes away, then as the aceton evaporates it leaves the plastic behind. No acctual chemistry, just a simple physical process. As mentioned in the other thread, gasoline si really the better solvent do to its easy attainment(compared to acetone) and its relative safety(again compared to acetone). The solution can be touched if you have no cuts or wounds on your skin, but is, after a certain concentration, extemly sticky. The solution can get very high concentrations until the consitency is mor eor less that of bread dough.
At big E: guitar picks, alogn with ping pong balls are made of celluloid, a highly flamable thermoplastic, it is barely used at all besides in these two items simply beacue of its danger and is composed of mostly nitrocellulose used in gun powder and gun cotton, ergo, its dangerous. Polysyrine is also flamable but not any where near as bad.