GENERAL
J-B Weld epoxy was used throughout this project. I found it best to apply the epoxy with a toothpick.
Red RTV (Hi-Temp.) can be used to seal and glue some parts on the outside of the stirling engine. Its cheaper and dries faster than J-B Weld, but its not as strong. Do not use RTV on the displacer because it has a high friction coefficent and will cause the displacer to drag if it rubs against the side of the pressure vessel. Also, because it is flexible, do not use it to mount and seal the power piston tube to the flat washer and to the side of the pressure vessel.
Small stainless steel scissors were used to cut the aluminum cans. The type that comes with a good Swiss Army knife will do.
A circular template (the diameter of the aluminum can) made from graph paper is useful for finding the center of a can.
When making the bottom and top of the displacer, a compass should be used to scribe the circle on the bottom of the can.
Use drops of superglue or slivers of tape to temporarily hold parts in place while epoxy sets.
DETAILS
Orient the displacer with the dished side down. Glue (with hi-temp epoxy) the 2 inch quilting pin to the top of the displacer. The pin should oriented in the axis of the displacer cylinder. Note that the displacer and pin will have to endure rapid up and down movement. It is left up to the builder to determine the best way to secure the pin to the displacer. However, one method is to insert the pin through a hole in the center of the displacer top, put a couple of bends in the end of the pin inside the displacer, and then epoxy the bent end of the pin to the inside of the displacer top.
Insert displacer into pressure vessel dished side down. Place top on vessel (dish side into vessel) and gently push the top into the vessel (dished side down). Note that the straight pin should protrude at least 1/2 inch from the hole in the top. Verify that the displacer moves smoothly inside the pressure vessel when the displacer rod (straight pin) is moves up and down. Glue (with hi-temp epoxy) the top to the vessel. This joint must be air-tight. Once the glue has dried, bend 5/16 inch of the end of the straight pin to a 90 degree angle. Be careful not to bend the portion of the pin that must pass through the hole in the top of the vessel
Bore a hole in the side of the PVC end cap for the copper tube to fit into. The hole should be low enough in the cap so that when the tube is installed it will not interfere with operation of the rubber diaphragm. Fit copper tube into the end cap and epoxy in place. Push the other end of the copper tube into the flat washer to make a flange and epoxy in place. Cut a 1/4" hole in the side of the pressure vessel near the top of the vessel. Position the copper tube flange (flat washer) over the hole. The open end of the PVC cap should point up. Verify operation of the displacer, and epoxy (hi-temp) the tube flange in place.
Punch a hole in the bottom center of the fire box. Fasten the fire box to the center of the wood board with a wood screw inserted through the hole. Gently push the pressure vessel assembly into the top of the fire box. You should be able to press it in about 1/4 inch. Be careful not to split the fire box. Cut an opening in the side of the fire box wide enough to insert a tea light candle through. The opening should be about 1/2 inch above the base and 1-1/2 high. Cut a slot in the upper back of the fire box about an inch wide and 1/8 inch high. Make a flat surface inside the fire box by filling it with paster of paris up to the bottom of the opening.
Fit the flywheel onto the crank. (Note: You will need to install heat shrink tubing spacers on the crank on one side of each support). Bend the end of the crank to 90 degrees and epoxy. Turn the crank/flywheel and eliminate as much wobble as possible. Install the crank in the support holes. Note that the crank is correctly oriented with respect to the PVC end cap (power diaphragm). Epoxy the supports to the side of the pressure vessel. A slot may have to be cut in the support that fits over the copper tube. Alternatively, the supports can be epoxied to the inside of the pressure vessel top. The holes in the supports should be about 2.5 inches above the top of the pressure vessel. The holes should be at the same height and in line with the displacer connecting rod.
Apply superglue to the rim of the PVC end-cap and press the rubber diaphragm onto the end cap. The diaphragm should be air-tight and loosely fitted, so that it does not stretch through the entire motion of the crank. At the top and bottom of the stroke the diaphragm should be slightly taut. The dish shape of the diaphragm should help achieve the range of motion without stretching the diaphragm. It is important that the diaphragm not resist (by stretching) movement of the engine.
Install the displacer connecting rod (aluminum wire) per sketch. Adjust the wire so that when the crank is turned, the displacer comes close to the top and bottom of the pressure vessel but does not touch. Tape a washer to the side of the flywheel to counteract the weight of the displacer. Turn the crank and adjust the location of the washer until the crank turns smoothly (i.e. the weight of the washer counterbalances the weight of the displacer). If a point can't be found, a larger washer may be needed. Superglue the washer in place.
Install the power diaphragm connecting rod per sketch. Note the orientation of the foot. Attach a square of rubber balloon to the bottom of the connecting rod foot with superglue. Attache the covered connecting rod foot to the diaphragm with a drop of superglue. Verify that the end of the wire is turned up and will not stick into the diaphagm. The diaphragm should move into and out of the end-cap when the crank is turned but should not stretch.
The engine should run off the heat from a tea light candle, assuming the flame is as intense as an average candle. Light and insert the candle into the fire box. After 30 seconds or so, gently spin the crank in the direction in which the displacer rises before the diaphragm.
The engine will run more efficient (faster) if some water is poured on the pressure vessel top (do not allow the water to flow into the pinhole in the pressure vessel top). The more water put on top of the vessel, the cooler it will stay and the faster the engine will run. A collar can be built around the displacer rod to keep water out of the vessel and the sides of the vessel top can be built up with a larger collar to make a space for holding water on top of the vessel.
TROUBLESHOOTING TIPS