Little Fluffy Clouds a.k.a Cutting Polystyrene, MacGyver-stylee
Problem Statement
Cutting polystyrene with a knife is messy and difficult
.
Sometimes we need a particular shape for a studio reflector, or packaging.
Chasing static-charged polystyrene beads for half an hour before giving up and picking them out of your coffee for days is not ideal.
Solution
Nichrome wire is a thin, strong wire that gets hot when you pass electrical current through it.
Expanded Polystyrene (EPS) is a light material that melts at around 240°C.
All you need to do is pass electrical current through some Nichrome to get it nice and hot, so that it will cut EPS. The 5V from USB on a 0.2mm diameter wire will make a 20cm long section of Nichrome wire reach a steady-state temperature of ~600C according to this Calculator.
The shorter the section of Nichrome wire you use, the hotter it will get. As you cut the EPS, the wire will lose heat. We are only cutting thin EPS sheets (~3cm), so we can use a short (~10cm) section of Ni-Chrome to get things pretty hot.
Tools:
Nichrome wire (we used .2mm) link
Alligator clip(s)
Polystyrene
A Battery
Glasses (Safety: It’s no accident)
Optional
A small spring
An unwanted micro usb cable
Wire-stripper
A metal washer
A thin metal ruler (like this)
A power-bank battery
Steps
Cut the end off the USB cable and strip the wires. Pop an alligator clip on the red wire.
Tie a loop on each end of the Nichrome wire. attach one to the spring (this is used for tension the wire)
Pass the other loop through the hole in the metal ruler and then attach to the washer (using this method)
Place (and fix) the ruler underneath the cutting surface
Attach the black wire to the metal washer
Fix the cutting surface to the table, floor, whatever it’s on
Hold the Nichrome wire to make it vertical by the spring (you might want to place a coin between the washer and whatever surface you’re cutting on, the wire will get hot)
Plug USB into power bank, attach the red wire about 10 cm from the point where it connects to the ruler using the alligator clip
Cut!
Video
PSA: Polyurethane foam should not be cut with hot wire tools. It needs a ton of heat, gives off toxic fumes, and leaves a lot of melted plastic wherever it is cut.
