DESCRIPTION

I built this Thermal Detonator Replica using ice cream scoops available from Target. If I was to do it again I would use 2.5" aluminum hemispheres available from JG Braun. I had to cut the handles off and do a lot of grinding. I used a small circuit for the random flasher. It has no sound unfortunately, but I think it looks pretty good. I am planning on using a magnetic reed switch as an on off switch by placing a magnet in the handle. As for sound probably the easiest will be to use a small digital recorder board.

This is a closeup of the actual prop

from the Smithsonian Exhibition.

Parts:

• 2 hemispheres (or cast aluminum ice cream scoops)
• 1 short section of aluminum tubing (for middle ring) or a section of ABS pipe connector
• 3 T-1 yellow LED's
• 1 red LED with lens
• epoxy putty
• 1 6052KT LED flasher kit
• 1 button battery holder and 3v battery from Radio Shack

Tools:

• drill bits
• countersink bit
• triangular file
• dremel with metal cutting wheel
• a short piece of string
• Sharpie fine point

CONSTRUCTION

Cast Aluminum ice cream scoops before parts removal and cutting.

Groove layout template, graph paper squares are 0.5 cm image is 3x3".

• The scoops are about 6mm in diameter. I had to cut off the handles, grind down and polish the sides. None of this would have been necessary with the hemispheres. I think the consesus is that 6mm is the correct size, the 2.5" hemisheres might be a little big but not really noticeable.
• Cut off about 1/8" off the bottom of each with a dremel cutoff tool. This is so it will be round and not egg shaped once the center ring is added.
• Find the center of the hemisphere and drill a small hole to thread a string through to use for placing the scribe marks with a Sharpie. See how it works here.
• Next file in the grooves with a triangular file. Much easier than using the Dremel!
• Figure out which sections need to be cut to make the "teeth" and mark them for cutting. You will use the cutting wheel again to cut these out about 3/16" depth.
• Drill your holes for the large led and switch. I made a slot for the switch but still haven't found the best way to set this up yet. I will probably make some contacts with copper flashing on the inside.
• Cut a 1/2" thick section of the tubing and drill the 3 holes for the small LED's.
• Sand and clean up the parts removing sharp edges etc.
• Glue in the tubing section and the LED's.
• Sculpt the handle over the top hemisphere out of epoxy putty. I put two screws into the handle that slide in the slot. The switch should cover the LED in the off position.

ELECTRONICS

The electronics were a bit of a pain but this picture shows how everything is layed out. I glued a piece of wood in the bottom for the circuit to mount to. The top just friction fits on to the bottom of the detonator. If you figure out a better way let me know. You will need to know how to solder and do basic electronics assembly to assemble the board and wire everything up.

Click on the picture for a larger version of the electronics layout.

Circuit Instruction sheet