Simple Stirling 1 Plans and Assembly drawings
May 20, 2008 – 6:13 pm
I have added color to the 3D CAD model. You can see it compared above with the physical prototype. There are a few difference between the two—the four support rods on the prototype are about 1.5 inches longer than on the plans. You might also notice I have the crankshaft set 180° from the CAD model.
The Adobe viewer for the 3D model gives you lots of flexibility to examine the design as a whole and the individual parts. You can even change the lighting and the rendering.
Parts drawings
The CAD parts drawings for all the parts are available. There are 16 unique parts that you have make. The only parts I didn’t put up are things like brass tubes and music wire that only have to be cut to a specified length. I’ll cover these in the bill of materials.
Assembly drawings
CAD assembly drawings plus the 3D model should make it pretty clear how everything goes together. I’ve put up 11 assembly drawings with section views.
I have to say the Alibre 3D design software has really saved me a lot of work. I’ll have to put up a post on that later.
What’s left?
A few more things I have left to post on this design:
1. The BOM (bill of materials)
2. Building instructions—I’ll put up some general instructions and some specific ones where I think they would be helpful.
3. Running the engine—this part should be fairly simple.
4. Modifications—Making it even better. For those who would like to get more RPM and power I’ll try out a version that uses a metal can for the displacer cylinder instead of the ABS (plastic) one. You’ll be able to run at higher temperatures.
7 Responses to “Simple Stirling 1 Plans and Assembly drawings”
Looks really good. Although I hope the BOM will include what “stuff found at the hardware store” you started with.
Then again, as long as you find something close it should work. I’m guessing the exact measurements of the non-attachment points on the crankshaft support, for example, aren’t too critical.
By DU on May 20, 2008
Oh wait, it looks like some of that at least is in the assembly drawings. Maybe I should read more carefully before I post.
By DU on May 21, 2008
Just finished building “Stirling 1″ from the excellent plans provided here. I find that there is quite a lot of resistance with the displacer diameter given in the plans. The gap between the displacer and the ABS tube seems to be just a bit too small so that air turbulences provide too much friction. Should I reduce the diameter of the displacer a bit? Have you had similar experiences?
By Markus Hehlen on Mar 22, 2009
The displacer and displacer shaft when assembled in the engine but not connected should move freely up and down. If you push it up with your finger and then let it float down it should do so with just its own weight in roughly one second. If it doesn’t come down under its own weight or does so very slowly (>2 seconds) then you need to give it more clearance and make sure the shaft is sliding freely in the brass tube.
By admin on Mar 22, 2009
Thanks for supplying the plans. The engine looks good but i have not succeeded in getting it to crank over yet and still deliberating just where i went wrong.
Hmmm my ABS fitting must be a metric not imperial 3″
…. lol. Is it possible to know how much clearance generally is needed between the displcer and the wall of the ABS connector fitting?
How many degrees is the piston crankpin offset to the displacer crankpin for best timing from power piston TDC ?
Cheers … Gar
By gargoyle on Dec 9, 2009
In my experience, there are only two likely reasons for the engine not running (assuming you are applying an adequate amount of heat):
(1) Too much friction: With the ABS displacer cover off you should be able to spin the crankshaft and it should coast for several revolutions before stopping. When you close the engine up it will not turn as freely due to compression and air friction, but the displacer must not contact the side. I try for about 1/16 inch clearance around the displacer. Make sure the displacer doesn’t contact anything at the top or bottom of its stroke too.
(2) Air leaks. If you’ve built this engine according to plans, the most likely area for a leak problem is where the ABS cover seals against the cold plate. The material I suggested gives me a good seal with just finger-tight turning of the hold-down nuts. If you don’t have the material I suggest, try to find something around 1/16 inch thick that is a fairly soft.
The piston crank pin should be offset 90 degrees from the displacer crank pin. It doesn’t need to be too precise; A few degrees off will not cause a problem.
By admin on Dec 10, 2009
Many thanks for the advice. It will be my workmanship somewhere along the line. Will double check the areas you suggested.
Cheers …. Gar (australia)
By gargoyle on Dec 11, 2009