Walking Beam Stirling Running

[RogerAS]

Greetings,

Today I got my model walking beam stirling engine running!

I don't have any machining tools so it has been a challenge. I made my displacer from offset printing aluminum plate, very thin and light. I cut discs for each end and wrapped those with a skin from said material. Both ends are flat and the displacer rod is a .125" brazing rod (1/8").

The gland/bushing for the displacer rod is a 308 Winchester rifle brass with 2 brake line reducers, slightly over .125" id, JB welded into each end of the brass. The spent primer was removed and the reducers act as one long bushing, sort of. This empty brass is jb welded to the displacer head, a 3/16" thick plug of aluminum, which is also the material for the walking beam. All the bearing points are VCR hubs/bearings. All the connecting rods are .125" brazing rod, jb welded to hub sections.

The flywheel is an old worn out skill saw blade, and the hole one uses to tighten or remove the blade was just the right size and distance to accept the crank throw. I soldered a VCR brass shaft "keeper" to the back side of the blade and clamped the VCR shaft via a set screw. The blades center hole had to be reamed slightly to fit the bigger end of the VCR motor brass part, and these are soldered together.

The plans called for a 1" id power cylinder but I used a free sample snubber (model# 2KS160S) from Airpot® http://airpot.com. This part is way undersized and will be replaced with a much closer to spec part soon (cylinder/piston part # 2K240). These are pyrex/graphite matched sets with super low friction and great sealing!

With no water cooling hopper the engine will only run a few minutes before the displacer head warms up and the engine slows to a stop. I'm using a propane torch as a heat source, for now. My best guess for rpm is around 80, and a correct sized power cylinder/piston should bring this number up a great deal.

Now, if I can just build a version 10 times this size! There should be some useful power to be had.

Image is the result of the kindness of fellow Fieldlines poster Peppa. More to follow on other subjects.

You've been warned. :-)

[TomW]

OK, Roger, just how many board feet can that cut in an hour? Inquiring minds want to know!

Cheers.

TomW

[RogerAS]

Tom,

To be honest I doubt that with the worn out teeth and lack of rpm it would do much damage to bare flesh, much less the softest wood. This is a learning experiment. I've learned I need some real tools! This model has very little torque. I'd bet I could stop it with my tounge, unharmed.

My goal is to get the small version running on a candle flame at 120-150 rpm. Then I wat to start scaling up the engine to the point I can create a sustained 100-200 watts. In conjunction with my convection wood furnace I hope to be able to augment my winter power requirements.

If I can make this work as I have imagined I will be able to avoid running the Kubota during those dead calm cloudy days (weeks) we have here in Arkansas during the winter. I can use the furnace hot air box and expose the cool end to the air. I may have to build a radiator/cooling system, but we'll see.

Those old time Rider-Ericsson hot air water pumpers were way cool and very reliable. I ain't sayin' I can build something that good, but everyone has a dream.

Besides, if I scale this up 10X where would I get a 72.5" diameter saw blade? :-)

I think the rain forests are safe for a few more days, from my efforts. :-)

[pepa]

hi rodger, very good use of materials on hand, i look forward to the next size up. i am still working on the heat engine for my boiler unit. the boiler itself is working great and i have the materials for the icemaker so a lot of work going on. have a good day, pepa.

[veewee77]

Where in AR did you say you were?

I live in AR, also, and have some ideas for stirling engines and would like to get together with you for develoment ideas.

I have a stirling engine I built up on youtube if you want to see it.

http://www.youtube.com/watch?v=TdI3x26fBs0

http://www.youtube.com/watch?v=YQVkjA_TqyQ

http://www.youtube.com/watch?v=x06hjb98wqU

It is made out of spray cans, candy tins, copper electrical wire, J-B Weld, solder, rulers, hard drive magnets (used for balancing the beam) and various other materials and items. It was fun to make and more fun to watch!

Doug

[RogerAS]

Doug,

I live in Stone County, 15 miles east of Mt. View. Where are you? Email me privately for more info.

I saw your engine already by searching Utube, prior to starting my project. Nice work.

I find it amazing that one can build one of these with junk.

I am quite open to cooperative efforts. My next version will be twice this size and with better methods of machining. Also I hope to be able to make it easy to take apart and service/modify. I'm considering how to use a regenerator to get a little more power out of this type of engine with a lower temperature difference. With very low friction these size/type engines should run from the heat of a candle. I want to avoid a water jacket if possible, and I'm looking at copper heatsinks for air cooling.

One idea I'm considering is a copper/glass/copper displacer cylinder. The hot end copper with a pyrex center section and then a copper cool end. Also I'm thinking of using both ends of the power cylinder/piston to move the working fluid. If the backside (exposed to atmosphere end) of the power segment was used the power should double. This would require a bushing/gland for the power cylinder similar to the displacer and tubing routed to the appropriate displacer points. Maybe the regenerator could be placed somewhere within this scheme.

I am not seeking to develope a commercial gain from this effort, but I'm not opposed to selling a few to cover R&D costs. I just ordered a larger power glass/piston set from airpot.com, much closer to the correct size. That set cost $41.88! For me that is a pretty serious investment, as is my time. However I do feel these are open source projects and I am willing to share all my results.

Thanks for the interest and comments.

[bob golding]

good work roger, i got one of those snubbers about 7 years ago glad to see they are still giving them away. you might like this site if you dont already know about it.

http://www.leebell.net/workshop/index.htm

some interesting stuff there.

bob golding