This simple Stirling engine was built with the plans
on this Japanese
site. Thanks to Koichi Hirata!
Here are some photos of my mockup:
Click on the thumbnails. If the the first picture comes without sound, click here to hear
the noises from this machine - use "endless loop" to get
the real impression. Far below is a second
set of photos.
Several details have been changed in regard to the
- My can was from champignons, 65 mm
diameter, height 100 mm (the can, that is).
- A rubber glove was used instead of a balloon
as the "diaflam" :)).
- The 4 original cardboard pieces on the diaphragm
are replaced by a 30 mm diameter cutout of a credit
card as a diaphragm stiffener.
- The bearings in wood have too much friction.
Replaced by credit card bearings.
- The proposed fixture of the wood piston by tying to a
paper clip was difficult to adjust. This was replaced
by a grey PVC part with
3 quickly drilled holes: a) crank hole b) fishing thread hole
c) 3mm screw hole. The screw must be
tightened only softly to secure the fishing thread
in position, otherwise the thread is sheared. So
fine adjustments of thread length are possible.
See detail photo.
- As a mass on the crank shaft I made a small
movable weight from a screw terminal and some washers.
- In the pictures, the outside boards are held in
place by a vice - later replaced with screws.
After some time, some further improvements were obvious:
Pictures (click to enlarge):
- The displacer piston is made from 10 pieces
of 6 mm balsa wood, glued cross-wise. The inner
6 pieces are actually rings to save weight.
- This photo shows the clearance between the displacer
and the tin can.
- The long crank shaft with the mass was replaced
by 2 old CDs with nice drawing and a 6.5 gram coin glued on as a
- Detail of 3.
- The double CD is connected to the crank shaft
with the red PVC part, turned on my Unimat model
- The credit card bearings were mounted level
with the wooden walls for better look and portability.
- The seal between the fishing thread and the
diaphragm rubber had high friction losses. The rubber
disintegrated during a few days due to the lubricating
oil. The rubber started to disrupt and air escaped.
Therefore I made a 0.8 mm hole with a hot needle
into a new diaphragm stiffener (credit card). This hole serves
now as a much better
and long lasting seal. This hole was surrounded with
handcut plastic washer as an "oil container"
- The diaphragm stiffener was
enlarged to 35 mm.
With these improvements the machine made respectable
143 rpm on a single candle as heat source.