The Stirling engine in this instructable is the simplest, safest engine I've found. It's a nice size, very sturdy, fairly cheap (if you have access to the tools) and makes a good project for learning to use tools and how physical concepts can be put to everyday uses.
The text of these instructions are also available on Google Drive at https://docs.google.com/file/d/0B_yXLsNjezyeXzVmSGc0QVZ6LVE/edit?usp=sharing
Below is a very brief introductory video. A more detailed overview of this engine is available here
This model is based on a design by Darryl Boyd (http://boydhouse.com/stirling/) with a few changes inspired by Junkie (http://sites.google.com/site/reukpower/can-stirling/stirling-generator-2) as well as several others.
You'll need the following:
Tools: Electric drill and metal bit set Screw drivers Vise grips Socket wrench set Hack saw Pipe cutter Sandpaper Awl (or long nail) Hammer Rat-tail file Scissors Metal snippers Carpenter's square Pliers Wire cutting pliers Boxcutter knife Clamps Table saw or hand saw Jig saw Can opener from Boy Scout or Swiss army knife
Materials: For the Frame -3/4 plywood (a 2ft x 2ft piece) -2 pipe straps (for 1in pipe) -about a dozen 1-1/2in drywall screws (or similar) -oak or hard pine strip (1/4in x 3/4in x 2ft)
For the Displacer cylinder -1 or 2 empty aerosol can 2.5in diameter x 8in tall (hairspray, bug spray, spray paint, etc) -4 or 5 12oz soda cans -2 coffee cans -old bicycle wheel- from at least 26in bike (ask local bike repair shop) -Steel wool - medium -Terminal blocks (regular and mini - from Radioshack) -High temperature RTV silicone gasket maker (from auto parts store)
For the Power cylinder -3/4in copper pipe (1 or 2ft piece from hardware store or ask plumber) -Repair pipe for 3/4 pipe - comes in 2ft pieces -3/4x1/2 Female adapter -1/2x1/8 Pipe bushing (1/8FIPx 1/2MIP) -3/8in Threaded lamp repair pipe (plus hex nuts) -1/4in T-nut (Aluminum binding post w/ screw) -5in clothesline pulley -long rubber bands (about 5in dia. to fit pulley) -JB Weld high temp epoxy (from auto parts store) -Valve grinding compound- water based (from auto parts store)
Other hardware for connecting rods: -3 or 4 clothes hangers (in good shape - not bent up)
for pulley axle: - #8x 2-1/2in bolt with nut and 4 washers - 2 nylon T-flanges - Threaded #8 aluminum spacers - one 1/4in, one 3/4in
for pulley arm: - #6x 1-1/2in bolt two 2 nuts and 4 washers - Threaded #6 aluminum spacers - three 1/4in
For beam: -#8x 2-1/2in bolt with nut and 4 washers - 2 nylon T-flanges - 1/2in T-nut (aluminum binding posts) - 1 washer to fit over T-nut - Threaded #8 aluminum spacers - one 3/4in - #8x 1in bolt and nut - 4 fender washers to fit
For generator: -small DC electric motor -small plastic pulley or screen door roller (screen patio door repair parts) -tubing that tightly fits the motor's axle to act as a bushing -nylon spacer that will receive the axle bushing AND fit the small pulley -extra large rubber band (about 4-1/2in diameter)
NOTE: The frame made in STEP 1 was made after I built this engine, so the frame you see here will look different than in later steps. The measurements are all the same, however. I thought I should show a more straightforward way of making the frame than I did before. The main difference is the placement of the 3 x 4.25in power cylinder mount.
Cut out plywood and mark as shown (Photo1). If you don't have a table saw, try to find a 2x2 piece with straight (factory cut) edges at a hardware store or cabinet shop, and then cut out your pieces with a hand saw, being sure to use the factory edges for any edges that will be screwed together. This will help keep your frame rigid.
Screw the pieces together thru the bottom of the 8x12 base (2). It's really not important that the pieces be straight on the line as shown, but the front edges do need to be flush or lined up together.
Center the long edge of the 4x12 back brace on the 2in mark (3). Screw thru the face of the 6x9 main engine mount, then up thru the bottom of the base as well.
Screw the 2x9 beam support to the brace, lining up the beam support's centerline with the 2in line on the engine mount.
Line up the centerline on the 3x4.25 power cylinder mount with the horizontal and vertical lines on the engine mount (5). You may want to put a small block on the backside, too, in case the screws stick out in the back.
Attach two pipe straps to the power cylinder mount so they are centered over the centerline (6).
Drill two holes to fit a #8 T-flange at the distances shown (6): 13-1/2in up from the base and on centerline of the beam support; 6-1/4in over from that same centerline on the main engine mount TIP: To help get these holes more perpendicular without a drill press, place a 1-1/2in block with a square edge next to your drill bit and use the edge as a guide to keep the drill at 90 degrees from the piece being drilled (7).
Finally, If you wish to mount a motor as a generator later, center a hole for your motor at 3-1/4in from the center of the hole you just drilled on the main engine mount.