Curving styrene without a vacuum?

How 'bout starting with a round base with a channel/groove in it the shape of the outer wall. Then start with a piece of thin styrene, thin enough to bend to the curve without heat, etc. Then add consecutive pieces until you get the right wall thickness. If not, a hair dryer works good at heating up enough to bend most styrene, followed by cold water(keep the dryer away from said cold water). Or try a heat strip for heating up plastic and bending.

Well this might be a stretch but you might be able to get it to work. You could just do paper mache. Using regular elmers school glue and newspaper scraps. If you first coat the bowl with a layer of the glue (probably should be thinned a bit with water) and then start adding glue soaked strips of paper and let it dry, you would get a fairly solid copy of the shape from which you would get the shape you want. The glue could be fairly easily painted, at least I think. Maybe instead of glue you could use plaster of paris and soak the strips in that. Just an idea.

QUOTE: Originally posted by DaveJames Couldn't I just drape the melted plastic over a plaster mold of a a cut up section of the bowl? (Hopefully that sentence made some kind of sense ) Or do you still need the suction to get the right shape and fit? There's no detail to capture, just a slight, rounded curve.

Dave;

What you're describing is actually a type of heat forming. Plunge molding. You could do exactly as you described.

To make sure you get it right though. You will need to make a frame to support all edges of the styrene to be formed. The frame does not need be an elaborate affair just sturdy and remain square when the styrene is heated.

Use two pieces of plywood of equal size with a hole cut in the center large enough to fit over your pattern yet small enough to hold the styrene firmly all around. Once you have this frame made. Clamp the styrene in a sandwich between the plywood and leave enough styrene around the edge to ensure a solid "grip" by the clamps all around.

Note **For cheap styrene source use "FOR SALE" signs from the hardware store**
These mold really easy and come in a large sheet for next to nothing in cost and will take paint easily and glue like regular sheet styrene.

Once you have the styrene clamped in. Heat it in a warm oven.
Note: **Do not leave the area or you will be cleaning styrene off your stove for years**

Once you see the styrene "droop" in the middle. Quickly and carefully move it from the oven and position it over your pattern. Press down equally on all sides and hold until it cools.

This method of heat forming was explained in previous issues of FSM check the back issues or the index for the full article.

If you need further help feel free to email me or reply here.

Cheers;

Gregory