A Stirling Engine Project

As part of a longer term project to build an Aluminium Forge blower using a Stirling, I decided to try and build a basic LTD to make sure I could get the damn thing to run.

I had to use whatever I had lying around to try and build it, so my materials list may not be the best, or the right way to do it.

I had a good look at a number of Stirlings on the net before I began. It was obvious to me that the most difficult part of the manufacture would be the sealed piston assembly and the linkages. These were cast using the resin process in one of my other instructables.

I couldn't get the video to embed correctly, so here's a link to the Youtube video:

VIDEO

 

Step 1: Materials

I used the following materials to build this Engine.

Two hard drive platters from a 3 1/2" HDD
3 CD-Rs
A 10p piece
A 2mm steel rod from an HP printer (scrap)
A 2.5mm brass tube (dunno where that came from)
A piece of 22mm (1") copper pipe
A plastic storage container (Tescos 78p)
A bit of sponge floor tile
Some resin and alginate
Odds and ends from old scrap printers
Various glues, solder etc.

My main goals were to assemble a working engine that looked nice without doing too much machining. Access to a drill press and possibly a small lathe would be an advantage.

Here are my main 'ingredients' from scrap.

Comments

[lithiumnights]

very smart looking sterling

[Mudbud]

I kno wthis is an old instructable but what is the copper tube for? I see the crankshaft with the poles, one in the copper tube and the other in the diffuser. whats the copper tube do/ do I need it?

[marshon]

The copper tube is the power cylinder, and yes you do need it or the motor wont run. Sterling engines require two pistons, one is a sealed unit (the power piston) and the other is the diffuser piton who's job it is to move the air in the system from the hot side to the cold side in order to run.

[Mudbud]

thanks. I guess I'll find the parts later then

[Kinnishian]

Hi. I really appreciate your instructable. It was the balance of feasible to find/make similar materials, and good design. If I can offer some feedback, some of those yellow boxes on your photos identifying the peices, like in other ibles, would have been very helpful for me. (I'm not quite done yet with my engine, i'll post a picture).

[acobalto]

Interessante, mas quanto tempo será ele aguenta funcionando ?

[spex]

hello have you any video of this engine?

[marshon]

There's a link on the introduction page.

[rimar2000]

Very good work, clean and prolix. I think the upper and lower CD must be painted with a black permanent marker, to enhance the heat transfer. It will be better if you remove before the aluminum coating.

[marshon]

Interesting, but there are no upper and lower CDs, they are metal hard drive platters and they don't have an aluminium coating. It would only be worth painting the lower hot plate since black attracts heat, the last thing you want on the upper plate. A better idea would be an ice container on the upper plate to increase the differential temperature.

[trike road poet]

Just to let you know, infrared is actually absorbed better by the color of green found on the bottom of an oak leaf, then black. Many black paints are in fact I.R. blocking, to prevent fading, and you will actually lose heat. You may notice that many of the professionally made solar collectors are green inside, not black for this reason. The closest color to the green needed is ironically good old army OD Green. (go figure.) [If you have your heart set on a black that is very IR absorbent, try the soot you get from a candle, there is no IR blocking in this material, and a spray of regular Matte finish clear spray from an art store will fix it in place.] This project is great, introducing casting, fabrication and unique materials. Seriously ought to win a prize, this is the sort of expansion on skills and knowledge that makes Instructables such fun! Thanks for the project, going to be my winter project.

[rimar2000]

Awesome that of green colour, I didn't know it! I agree with you about this instructable, it is very good.

[drorosz]

Just how big is a "10p" piece??

[marshon]

About an inch in diameter, but any metal disk the right size to seal the hole in the platter will do the job. I just happened to find that a 10p piece fit the hole.

[rimar2000]

Pardon, as I speak Spanish, not English, I do a superficial reading on the long texts. So, I don't saw the detail of the hard disc plates, only saw the photos. I insist that both sides should be black. A black surface is permeable to heat in both directions, and the Stirling engine, as a thermodynamics application, is not nothing but a converting heat into motion. More heat transfer, more effectiveness.

[alienwear]

He is correct, black heats up quicker, but cools down faster as well. Both plates should be black for maximum efficiency.

[dylanyoung]

this is cool.....but is there anything i could swap for the resin???????? 5*

[liam2317]

Copper pipe/tubing. You can buy two sizes that fit very closely within each other. You will still need something to fill the inner tube with though, but at least this way you don't have to make a perfect cast.

[marshon]

For the power piston you can basically use anything that will give a seal and still run with very little friction. I've seen pistons made from epoxy putty, JB Weld, graphite, nylon and aluminium. I use resin because it's very easy to work and get a good finish. For the bearings, you could use a hard nylon like Delrin, Teflon or acrylic. For the crankshaft you could obviously use real bearings. I'm currently working on another engine using hard drive bearings for the crankshaft.

[alcurb]

Very nice photography. In the final picture, the flywheel looks like machined brass. Kudos.

[Nicola Tesla]

amazing 5*

[Phil B]

This is the best description of a Stirling Engine project I have seen. I would like to try it sometime. Thank you.

[marshon]

If you decide to make one here's what I learned. Don't try to glue the diffuser cylinder together. It would have been far better if I had used a slightly smaller food container or a bit of 3" plastic drainpipe and bolted through the outside with a pair of gasket seals. The glue simply cant keep a seal against the polished surface of the platters, especially once it gets hot. I am constantly patching little leaks that develop.

[Phil B]

Someone gave me a kit for a Stirling engine. I have not had time to finish it, yet. One step had me gluing a brass connecting rod guide to an aluminum disc, but it did not stick. I need to re-engineer that step. Most of the kit is pre-punched cardstock. Thanks.

[AndyGadget]

Whoo - That's quite a project. I bought one of a similar design some time ago. Congratulations on getting the power piston friction low enough and the displacement disc rod seal good enough to work - That must have taken some time. Mine has a glass tube and a graphite piston and bearings.

[marshon]

The resin is quite forgiving as bearings. I just drilled the holes the same diameter as the rods, an sort of forced them through and a bit of spinning beds them in. Very little friction. However I am thinking of another one using HDD bearings.

[pilotox]

Congratulations, it looks very professional!