I have simplified the original Tin Can Engine to make it easier to build and to use materials that are easily available. No soldering is required and it can be made using only hand tools.
Here's what you need:
I will send the file to you as soon as I see your request but don't forget I may be out when it arrives. Also remember I am in the UK so I could be in a different time zone than you.
If you put "E Z Stirling" as the subject in your email this will ensure it does not go to my spam folder.
1 200g Travel sweet tin, eat the sweets! The tin is 97mm diameter and 40mm high.
If you cannot get a sweet tin click here.
Plastic bottle top.
3 screws and nuts.
Some builders have mentioned that they cannot get balsa wood or the specified sweet tin.
Using a much larger tin will alter the design and it may not work.
Click here to see suggested alternative materials for the tin and displacer.
There is a link to a further video showing the methods of construction.
Print out you template sheet. It's drawn A4 size. You can check if your printer setting are giving the correct size by checking the length of the horizontal and vertical scale on the sheet. Its not that critical a 1mm error is fine. You may have to adust your printer settings to get it the correct size. On my HP printer I select "Print Actual size" and check the "Choose paper source by PDF page size" box.
MDF can tear when holes are drilled in it, depending on the quality of the product.
On parts like the flywheel hub where accuracy is needed to locate the hub, superglue can be applied to the part before it is drilled and this will make the MDF much harder. I also apply a coat of superglue to the base parts and let it dry . This stops the glue soaking into the MDF when the rubber glove diaphragm is fixed.
The following tips corresponds to the Youtube video timeline.
01:48 The parts are drawn actual size but I suggest the strips at the top right are left a little overlength and sanded back to size after they have been assembled.
04:50 Position the vertical part to the just meet the large hole in the base.
05:28 If you don't have a pillar drill, I suggest carefully marking and drilling the holes
from both sides. Drill the hole 3.2mm dia and 7.0mm down from the top.
06:40 Disposable latex glove is used.
07:00 Before fixing the diaphragm, the base has been primed with a coat of superglue and left to dry.
07:46 Do not stretch the glove too tightly but ensure there are no wrinkles.
09:20 This template has a circle drawn in the centre as an alignment aid for the small MDF disc.
09:43 The small MDF disc that was cut from the plans is used to attach the displacer rod to the diaphragm. Drill a small hole in the centre and the rod is a push fit. A small drill could be made by using a bit of the same wire used for the rod and shaping the end like described below (11:43). If the fit is a little loose a spot of glue can be used.
11:00 This joint must be completely airtight. If not the engine will not run. The biggest cause of a non running engine is an air leak,
11:30 Removing the "nail" from the Pop rivet.
11:43 These parts are used for the crankshaft bearings and the displacer gland. It is most important that the fit is very free with little friction. I found the nails that came with the stainless Pop rivets had a slight bend in them which made them unsuitable. I substituted a steel nail from a similar size of aluminium rivet. If you can feel any rough areas on the nail then carefully smooth with a fine file. Metal polish can be used to get a free running bearing and if all this fails, make up a simple reamer like shown below by filing a flat at an angle on a pop rivet nail. Hold the rivet head and work the reamer up and down whilst applying a twisting motion.
11:46 A blob of silicone sealer to ensure the gland is airtight.
13:36 This template has a point marked in the centre to mark the lid centre.
16:10 This hole does not need to be neat. It only provides clearance for the power piston and won't be seen when the engine is finished. Use a fine file is you don't have a Dremel
or similar tool.
16:50 This hole is 18mm diameter. Its size is not too critical. It has to give clearance for the small disc on the end of the crankrod.
17:35 Pilot holes are drilled for the small screws.
18:20 This is bathtub sealer.
20:00 It is important this joint is airtight. If not the engine will not run. The biggest cause of a non running engine is an air leak. Clamp and leave to cure overnight.
20:19 Roughen the CD with sandpaper to give a key for the superglue.
20:30 Use the template to centre the hub.
21:00 The crankshaft is 20mm long.
21:12 Try to get the disc to run true before the adhesive sets.
21:17 The crankpin is 11mm long.
21:50 Position the wood grain at 90 deg .
22:30 The diameter of the displacer is 9mm less than the outside diameter of the tin. This gives a gap of 4.5mm between displacer and tin.
Mine came out at 88mm.
22:40 Use the full length of the Pop rivet nail for the displacer rod.
24:38 Make the bend 6mm from the centre of the loop.
24:52 The connecting rod is made in a similar way to the crank. Its length can be adjusted later.
With the crankpin in the horizontal position make sure the diaphragm is not pushed up or down. Rotating the flywheel should give the diaphragm an equal up and down movement.
25:35 The flywheel must rotate very freely.
26:38 The crankpins should be positioned 90 degrees apart, i.e. when the displacer rod is at the bottom of it's stroke, the diaphragm rod should be horizontal (left or right determines the direction of engine rotation).
28:35 Cable insulation holds the thread to the the displacer rod.
29:16 Adjust the length of the thread so that the displacer nearly touches the tin lid. When assembled with the tin bottom the displacer should move up and down without touching the top or bottom. If this cannot be achieved then a shorter crank should be made.
29:28 Tape is used as a temporary seal to test the engine. Later silicone sealer can be used in it's place.
32:20 Lamp oil is used in the burner. Only a very small flame is needed. The larger the flame the faster the engine runs, this is not meant to be a high speed engine though considering the materials it is made from.
A larger glass bottle is better for the burner than the one in the video. As the small one heats up the fuel vaporises and causes the flame to get larger. This overheating could result in damage to the engine.
An improved design is shown below. This a vinegar bottle with a brass plumbing end cap and small copper tube fitted. A taller can is needed with this burner but it will burn all day without flaring up.
Apply a drop of oil to the crankshaft and on the crankpin. Also put a drop on the displacer rod where it enters the top of the tin. This will lubricate the rod and help make an airtight seal.
What if it doesn't work?
Firstly check the parts run very freely like mine in the videos. There is little power in this engine so it needs to be a free as possible. Make sure the connecting rod eye is square to the flywheel and not binding.
Make sure the displacer crank and flywheel crank are positioned 90 degrees apart.
Check for air leaks.
Disconnect the connecting rod from the flywheel. Place the engine on the burner and move the displacer up and down by pulling on the thread. If there is little or no movement of the diaphragm, you have a leak somewhere. Check the displacer gland and the seal where the base is attached to the can lid. Maybe your engine runs but only for a short time, squirt some WD 40 oil around the outside of the MDF base whilst turning the engine over. Any leak will show as air bubbles. Don't do this if your MDF is not painted as it will soak into the MDF and swell it up.
Your diaphragm may be too stiff. On the gloves I have used a squirt of WD40 softens up the diaphragm. With the flywheel disconnected and the displacer operated by hand the connecting rod needs to be able to move slightly more than the crankshaft throw.
Make a pressure tester
As mentioned above the most likely cause of a non runner is an air leak. Pay particular attention to where the base meets the tin top and where the two wooden parts sandwich the diaphragm.
Get hold of another sweet tin and poke a small hole in the side near the base using a nail. Attach a short length of small tube using epoxy or car body filler. Mine was copper but could be any material, plastic is OK perhaps from a ballpoint pen. Be sure to seal where the tube enters to make it airtight.
Now fit a short length of flexible tube as shown above. Fit the engine top to this temporary bottom and seal with tape as before. Gently blow into the tube. The diaphragm will be pushed up and if there are any air leaks you will be able to hear a hiss as the air escapes. Apply a fillet of silicone if it is around the base.
Here is a short video of things to try if you cannot get your engine to run.
If you do build one of these send me a photo I can add it to the gallery for others to see.
GALLERY of E Z STIRLING ENGINES by other builders
The engine described has little power and serves to demonstrate the Stirling cycle principle.
The Stirling cycle can been used for developing real real power though, some examples are shown below.