Today we experimented with crayons. We gradually heated a hot melt glue gun (that we adapted for crayons) starting at 109 degrees, we notched up the temperature with a rheostat until the crayons melted enough to extrude a bead. At about 113 degrees it worked. We notched the temp up to 127 degrees to try different viscosities of melted wax and feed rates. We discovered that crayons need to be preheated – so a heat tube on an extruder should be the length of the crayon.
We also discovered the pitfalls with melted crayons. The hardened beads are very brittle and, even though it seemed great that they harden in seconds after being extruded, they do not self adhere well. Whatever we create with crayons will probably be very delicate.
So, even though the experiments were encouraging, and they clarified some design questions, we are migrating to a more consistant and robust medium for now. latex caulk (mostly because of time and deadline considerations).