Step 4: Making the hot wire lathe
In order to construct the probe you will have to make the casing. Polystyrene (Styrofoam) is an excellent choice, because of its heat insulating properties. We used Styrofoam enhanced with graphite. The graphite enhances thermal insulation by 20%.
Before making a probe, you will first have to make a ''lathe''. First make the wooden holders for the end plates. For the end plates you can use any rod or stick, as long as it is thick enough to mount a plate on its end. Just place them into a ball baring and attached to the wooden holders. Then put a round or square plate on each of them. We used 25 mm thick aluminium rods and for the ends we used round aluminium plates (diameter 100 mm and 135 mm).
In between two end plates you will later put the polystyrene block.
With lab stands and some clamps you can make a stable holder for the hot wire.