Here is a list of the materials you will need to build Jan Ridders‘ new simple low temperature differential Stirling Engine. You can download the plans here (PDF).
I was going to build his Coffee Cup Stirling but I have started building this one instead because it will take a lot less time. I have not been able to spend much time in my workshop lately, which is typical during the warm weather months, and I would like start a project I can finish within a reasonable amount of time.
I know I get a lot of visitors looking for information about Jan’s Stirling engines, so I am posting this with the hope that someone will find it useful. I usually hate studying plans to determine what materials and tooling I’ll need to buy. I’m always worried I’m going to miss something and the project will grind to a halt while I place an order and pay a huge shipping fee for just one item. I’m not too fond of ordering stuff either.
Fortunately, I already have almost everything I will need. I just have to buy the graphite, a glass tube for the power piston cylinder and a suitable plastic tube for the displacement cylinder. I did some checking last week and I think the glass and graphite will be easy to obtain. Finding a 4-inch clear plastic tube has been a problem. You really can’t make the top and bottom plates until you know dimensions of your tube.
Jan’s plans are in Metric units and I’m in the US, so I am going to have to convert them to English units. I have not built this engine yet, so consider the fractional English sizes I listed to be just suggestions for now. Stayed tuned because I’ll start posting some construction photos and notes soon.
- 18 mm [.70 ~ 11/16-inch] round – Countra weight (Counterweight) – Sheet 6
- 20 mm [.78 ~ 3/4-inch] round – Displacer kernel (Hub) – Sheet 5
- 32 mm [1.26 ~ 1-1/4-inch] round – CD kernal (Hub) – Sheet 6
- Material to make two 112 mm [4.41-inch] diameter disks for the top and bottom plates of the displacement cylinder. One needs to be 5 mm [.20-inch] thick and the other 8 mm [.31-inch] thick.
You have a couple of options here. One is to start with a couple of disks cut from a 112 mm or bigger round bar. This could be very expensive if you have to buy a length of it.
A cheaper alternative is to make them out of a flat plate by following Bogstandard’s excellent tutorial. You also have some choices if you do it this way. You can buy your aluminum plates in the two thicknesses you’ll need or use the same thickness for both cylinder plates, which should look and work fine. You can also mill the metal down to the thicknesses you’ll need.
- 5 mm [.20 ~ 3/16-inch] round – Fork (2) – Sheets 5 & 6
- 11 mm [.43 ~ 7/16-inch] round – Crank webs (4) – Sheet 7
- 1 mm thick x 6 mm wide flat stock [.04 x .24 ~ 1/32 x 1/4-inch] – Displacer & Piston Rods – Sheets 5 & 6
- 2 mm [.08 ~ 1/16-inch] round – Fork/Clevis pins – Sheets 5 & 6
- 2.5 mm [.10 ~ 3/32-inch] round – Crankshaft parts – Sheet 7
I recommend using .0940 (3/32)-inch W-1 drill rod for these parts. I like drill rod because it is ground to close tolerances, polishes nicely and resists rust well.
- 12 mm [.47 ~ 1/2-inch] round – Point Bearing Holders (2) – Sheet 7
- 6 mm [.23 ~ 1/4-inch] round – Bushings – Sheet 6
- 8 mm [.31 ~ 5/16-inch] round – Displacer Shaft Bearing (Seal) – Sheet 5
- 14 mm [.55 ~ 9/16-inch] round – Power Piston – Sheet 6
(depends on the inside diameter of the glass tube used for power cylinder)
Fasteners & Threads
- Machine or set screw for flywheel hub & tap: M2 x 0.4 [40-4] – Sheet 6
- Displacer shaft, fork and hub: M2.5 x 0.45 (tap & die) – Sheet 5
- Piston fork: M3 x 0.5 (tap and die) – Sheet 6
- Point bearings (2): M4 x 0.7 machine screws or threaded sections to make the point bearings, plus two stop nuts and a tap – Sheet 7
- Balsa Wood – to make a 100 mm [3.93-inch] diameter x 5 mm [.20 ~ 3/16-inch] thick disk for the displacer on sheet 5. The exact diameter will depend on the inside diameter of your plastic displacement cylinder.
- Compact Discs (2) – Used for the flywheel – Sheet 6
- Glass Tube – 16 mm [.63 ~ 5/8-inch] outside diameter / 14 mm [.55 ~ 9/16-inch] inside diameter – used for the power cylinder on Sheet 6.I found some test tubes that were the correct diameter and here is how I cut them to the correct length.
- Silicon Adhesive (clear) – Used to attach the top and bottom plates to the displacement cylinder and also the glass power cylinder to the top plate.
- Glue – To glue the two CDs together and to the flywheel hub.
This is the first time I’ve made up a materials list like this and it probably won’t be the last. I would appreciate any suggestion you may have for doing it better the next time. Unfortunately, I can’t put it in a table because WordPress doesn’t really support them.
I would like to know if you have any questions or find any mistakes.