Originally designed for use in a Baja SAE pneumatic timing gate system. This simple diaphragm switch is designed to be cheap to build with mostly store bought hardware and to operate at very low pressure differentials, in the neighborhood of 1-2 psi. Positive pressure on the inlet presses a brass washer into 2 brass dome nuts which completes the circuit across the top terminals. Printed with ABS but other materials may work as well.

Printing Recomendations:

• Print with mating surfaces upwards for more accurate o-ring and bore surfaces and no supports.

Tools Required:

• Exacto knife/box cutter
• Soldering Iron (with heat insert bits)
• Screw driver and bits

Hardware:

• Nitrile Glove QTY: 1 (Diaphragm)
• 211/G22 O-ring QTY: 1
• 1/8" Hose Barb QTY: 1
• 3/4" OD Brass Washer QTY: 1
• 6-32 X 1/2" Brass Screws QTY: 2 (Terminals)
• 6-32 Domed/Acorn Nuts QTY: 2 (Terminals)
• M3X6X5 Heat Inserts QTY: 4
• M3X20 Screws QTY: 4 (Mounting)
• M3 Flat Washers QTY: 4 (Mounting)
• M3 Lock Washers QTY: 4 (Mounting)

Instructions:

• Use printed template to cut diaphragm from nitrile glove.
• Press heat inserts into 4 cornes of bottom part.
• Insert hose barb and tighten until flush or nearly flush with opposite side of bottom part.
• Screw terminals into domed nuts through top part.
• With top part flipped upside down (lettering down) lay brass washer in bore resting on top of domed nuts, place o-ring in slot, then lay diaphragm over o-ring centered as well as possible.
• With top part still upside down, align bottom part and press together.
• Hold pieces together and insert 4 mounting screws with washers through top part to fasten assembly together.