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is there anyone that can make a machine to chamfer edges on polystyrene cake dummies ? Answered

We are struggling to find someone to help us make a perfect cake dummy made from polystyrene, we can cut the circles out no problem at all but cannot seem to get a perfect edge around the dummy, Have tried hot wire and a heated aluminium block but quality is poor. Maybe a router or a milling machine?


Could be done with a router table very easily. How deep a chamfer do you need ?

It might be possible to sand on as well, but you need a turntable to spin the work on.


Which one ? Sand or rout ? Either should work, but they'll need a gentle touch. Sanding's probably safest, come to think of it - the pressue of the cut would be spread out better.

Perhaps freezing the polystyrene first might help too. Reduce the amount it squishes away from the cut.

Microplanes might work too, but they don't make a radiused rotary one.

Interesing idea for sure. I wonder if it does make it appreciably harder ?

No it doesn't - there is little water in the material and it's construction is fixed on cooling below the fluid temperature.

Best option select extruded insulation polystyrene. Any builders merchant should be able to supply in 2 foot x 4 foot batts.

Build a simple hot-wire cutter and mount the cake on a turn-table (lazy susan). You can get the parts for the hot-wire cutter from Harbor Freight or eBay.

Basically, a wire is stretched between 2 conductors (thin heated knife blades mounted in 500F epoxy from Wal-Mart) and a controllable transformer is used to run electricity through the wire to heat it up.

Build a wood support to hold the knife blades (epoxy acts as an insulator - don't try to use the least amount possible)

The wire is stretched between the two knife blades that are sprayed with a release agent for whatever plastic you are cutting.

The epoxy as an insulator cools below the burning point of wood. If concerned a heat sink in the epoxy between the knife blade and wood will dissipate the heat so it won't burn the wood.

The transformer converts the 120VAC to a floating low voltage current so you won't get shocked.

Simply angle the wire and blades to cut out the chamfer as you rotate the turn-table (lazy susan). Use in a well ventilated area.

Adjust the heat on a test sample to make sure it's not too hot, or too cold.

Other similar tools can be constructed to create ornate designs.

Just a suggestion

We have to produce a large quantity at a time, or at least turn them out quickly. I think a router would be the best option - with a air filter for the particles. Is there anyone on the forum that can build machines like these, we have tried localy without any success ! if googling "chamfered cake dummies" it shows exactly what we are looking for :)

If you are using polystyrene with large bubbles in it try denser polystyrene, if you use a polystyrene with very small bubbles you can shape fine details in it with sand paper.


Have you thought about doing it with a solder iron and melting it, like you would with a hot knife or wire

What powers your hot wire?

It may be a matter of practice, and learning specifics of what leads to poor quality or good quality. When using a hot wire, you might adjust current to the wire, or cutting speed.

If you can't quite get that dialed in, you might have to spend time sanding after the hot wire.

How about making yourself a hot knife with a special loop on the end of it for rounding your corners their are lots of Ibles on the site to make hot knives just do a search i'm sure you could come up with a specialty tool of your own ...

White polystyrene which is made from bonded polystyrene beads is very difficult to work with other than a hot wire - You could use a stiff wire and shape it then turn the cake under the wire

Insulating Polystyrene - often pink or blue is extruded and very fine grained this sands and works easily and you could do as Steve says.

What quantity do you need to round? Are you wanting to manufacture lots? Is there a reason you've not bought those cake dummys that are already available?

Another possible option....

Buy expandable polystyrene and fill a mold with it.