Little Off Topic, Cutting Styrofoam

[chriskat]

So what I need to do is cut two styrofoam spheres in half, one is smaller than the other.

The inside of one half of the larger sphere then will have to be hollowed out so that half of the smaller sphere will fit inside of it. I really don't have any way to do this with heat.

Any ideas how I could go about this? Maybe a fine metal cutting blade, like a hack saw, to cut them in half. But how to hog out the larger sphere?

My daughter has to make a 3D model of a bacteria cell that is shown as spherical with two layers.

Thanks in advance.

Jeff

[TECHSHOP]

If you can't use a "hot wire" cutter, the use a "fillet" knife. Usually any attempts at "sawing" styrofoam makes a static charged mess.

[Thruthefence]

I have actually used an electric carving knife to cut foam. Not sure how to hollow out the center, tho.

[macona]

Like TECHSHOP said, a hot wire.

Piece of nichrome wire. Hook it to an adjustable power supply. Use a straight piece of wire to cut them in half then use a heavier piece of wire to make a loop on the end of the stick to make something like a ice cream scoop to hollow them out. You dont want the wire red. Just hot enough to slice through without melting the surrounding foam.

A car battery charger might work. Hard to say though, there are a lot of variables here.

[Evan]

Crush some glass to a coarse loose powder equal to about 20 grit. Stick a spare small sphere on a broomstick end with low temp hot glue. Paint small sphere with white glue and thoroughly coat with crushed glass. When dry use in lathe or drill press to grind out a matching cavity. Keep a vacuum handy during the operation.

The best way to crush glass is to use a short length of pipe, maybe 6" long by 2" diameter and weld it to a small piece of plate. Then drop in some chunks of broken glass and use another chunk of bar stock like a pestle.

[Mike Burdick]

For cutting the spheres in half Harbor Freight sells a hot knife for $14.99. If you sign up for email advertisements than every Thursday you'll get a 20% off coupon for any single item.

Might be worth a try.



http://www.harborfreight.com/cpi/cta...emnumber=66182

[mechanicalmagic]

Low temp, hot melt glue is good for styrofoam. Typically does not deform the material. Good for mounting the stock.

All normal tooling works fine, but creates a big dusty mess.

A radius cutter, like a Holdridge would make short work of the job.

DJ

[dp]

For a one-off project like this a razor blade will do the trick.

[winchman]

Get some balloons, put a couple inside each other before inflating the inner one, spray the balloon with PAM (as a release agent), and then paint the surface with latex paint (cheaper than glue) as you lay on narrow strips of paper (from shredder?) to build two half-spheres.

When the paint dries, deflate the inner balloon, and peel the outer one off the inside of the half-sphere.

The paper/latex shell should be as strong as the styrofoam without all the trouble and hazard of styrofoam dust.

Roger

[JCD]

I've had good luck grinding the stuff with a sharp coarse aluminum oxide wheel or disk.