I have my vertical heated wire table I built a while back that works quite well and will cut foam up to 6 inches thick. Recently I was given a truck load of FREE styrofoam, only problem was that it was 4x4 foot sheets 12 inches thick! I needed to build a jig that would slice it into thinner sheets that I could work with.
I started with a 4x5 foot piece of 1/2 particle board, the heated wire runs across the center of the long dimension. I attached some 2x4 brace pieces to the particle board and attached the uprights to the particle board and the braces. A crossmember runs across the top of the uprights. I could have made the uprights 13 inches tall, it would have been tall enough for the foam to slide though laying down- but I made the uprights just over 4 feet tall so I can slide the foam through standing on end. Now I can set my heated wire 12 inches off the table and cut 1x1x4 foot blocks.
(The picture above shows my original design with the heated wire attached to eyebolts, described here is the modification I made) I bought some threaded rod and made a bracket on each side of the uprights. NiChrome wire (bought on E-Bay) is connected to one threaded rod with a heavy wire hook and the other end of the wire is attached to a small spring. When the wire is pulled across the table and the spring hooked to the other threaded rod, the spring is stretched slightly. As the wire heats, it stretches some, the spring takes up the slack and maintains tension on the wire. The wire can be moved up and down the threaded rod to adjust the cutting height, but it will not slip or move on it's own because of the threads.
A small elecrical box was attached to one of the uprights and a dimmer switch was installed. 110 volts runs to the dimmer switch and to wires running to each threaded rod. A ring terminal at the end of each wire holds the wire to each threaded rod bracket.
CAUTION- DUE TO THE 5 FOOT LENGTH OF NICHROME RESISTANCE WIRE, THIS SYSTEM WILL NOT WORK ON LOW VOLTAGE. THE ENDS OF THE WIRES ARE EXPOSED, AS ARE THE THREADED RODS. AS LONG AS THE RESISTANCE WIRE IS IN PLACE, I DON'T THINK IT CAN SHOCK YOU - BUT IF THE WIRE COMES OFF, IS TAKEN OFF, OR BURNS IN TWO, THE EXPOSED WIRES CAN GIVE YOU A NASTY 110 VOLT SHOCK. USE DUE CAUTION!
The dimmer switch is started at full off and gradually increased
until the wire just starts to stretch, it should be then hot enough to cut slabs of foam.
Total cost of this table was about $20.
