Turtle Sense casting instructions for Smart Sensor and connectors

Overview

The Smart Sensor circuit board is coated in epoxy and then cast into a 1.5" diameter sphere of quick setting polyurethane resin. The back end of both mating halves of the Molex connectors are also cast in the same polyurethane resin, in order to prevent flexing of the wires between the end of the cable jacket and the Molex connector. Flexible silicone molds were used for the casting in order to make it easy to produce a quantity of sensors and connectors.

Materials used

• Tap Plastics "Platinum" silicone two part mold making material
• Tap Plastics "Easy Cast" two part epoxy resin
• Tap Plastics "Quik-Cast" two part polyurethane casting resin
• Pol-Ease 2300 spray release agent (optional)
• Small plastic mixing cups and wood stirring sticks
• 91% Isopropyl (rubbing) alcohol
• 5 minute epoxy
• Short lengths (< 3"). of 1/4" diameter, 1/2" diameter, and 3/4" diameter wood dowels
• Vaseline
• A plastic ping-pong ball
• A plastic drinking cup or round food container between 2.5" to 3.5" diameter. The cup or container should have a slight taper.