A Ringbom engine

[DavesWimshurst]

I don't think I've shown this one.
A couple of years ago I built a Ringbom engine.  It is a variation of the Stirling which uses the internal pressure variations to move the displacer piston.  The oversized piston rod provides enough piston area to lift a light weight displacer piston.

A quick video


The hot end is thin walled stainless, machined from the solid, twice!
Dave

[sbwhart]

Hi Dave

Thats a Nice little engine 

Thanks for showing

Stew

[bogstandard]

Dave,

Very nice indeed.

I personally think it will be a Stirling type of engine that will finally deliver the solution to fossil fuel powered engines. The Japanese already have a 'car' running on a Stirling, and they have already been proved in the third world that Stirlings running off sun power can be used very efficiently for pumping water and other such things, now if they could only get one to run off moon power.

I don't know if Dr Stirling ever envisioned that his theories and designs might just save the planet, but he does deserve a lot more recognition than he already has.

Stirlings have always fascinated me, but I have only ever built a low temperature one, and it did run, but that was disabled because my gorilla fingers fumbled and I dropped it. It now needs a rebuild.

I do have all the bits of materials in my storage area for a complete assault on all the Stirling types, just finding the time to do it is always the problem.

Maybe one day.........

John

[Divided he ad]

I like that noisey little blighter Dave 


I've always like Stirling's never thought myself precise enough to make one though..... One day? 



I've seen Johns Stirling.... It is in a bit of a sorry state    .... John, Maybe after Xmas (knowing all your commitments to shows, halo's  n other stuff) you would consider putting the little fellas together? Those very attractive flywheels you made should be allowed to spin.... It's all they have to do in the world!   



Dave.... Are you currently building anything.... Have you any project logs started? (I'm going to have to pay more attention to the forum!) if not, then I think you would have a lot to show many of us     







Ralph.

[rleete]

That's pretty neat. 

I've always liked the idea of Stirlings, simply because you can run them without having to have an air line snaking through the house.  Was this one as fussy to get to run as a low-temp ones?

[Darren]

That's an interesting engine....

[DavesWimshurst]

Roger,
I followed Dr Senft's procedures in his book "Miniature Ringbom Engines".
There are two critical fits involved, the power pistod and cylinder and the displacer rod and bushing.  The power cylinder is brass and the final finish was by lapping using a non embedding compound (Timesaver brand) and homemade expanding lap:



The piston is graphite as used for EDM machining, it was turned to a very close fit.  The displacer bushing is also graphite bored to size and the outside grooved for epoxy to hold it in its housing.  The piston rod is stainless steel drilled to make a thin walled tube, I believe there is a piece of scrap where the drill came out the side from not clearing the drill often enough.
The outside is turned and polished to a very close fit in its graphite bushing.  In fact if it runs for more than about five minutes the rod has heated enough to expand and stick stopping the engine.  After cooling it's fine again.  It"s a great little engin to take to our weekly "Techie dinner".  The restaurant is used to us by now!

Some time I'll get my act together enough to do a project, IVe only had my camera for a few mounths and am still not used to having it in the shop on a daily basis, maybe I need 

Dave

[rleete]

Thanks for the info.  That lap is an interesting idea, I might have to try it.

One more question: where did you get the graphite?

[sorveltaja]

In fact if it runs for more than about five minutes the rod has heated enough to expand and stick stopping the engine.  After cooling it's fine again. 

One possible way to fix that would be to make bushing and piston rod from the same material, so that their heat expansion rates are almost equal.

I've built similar engine, and used brass for bushing.
Thin walled brass tube (from an old telescope antenna)for piston rod. It's much lighter, and has already smooth surface.

[DavesWimshurst]

Roger,
I got the graphite from McMaster Carr.  I bought it years ago and the catalog listing has varied but I think the material is called high temperature conductive graphite.  Some have said that certain grades of EDM electrode material is abrasive to machine but I had no trouble with what I used.  There may be some highly engineered grades that we don't want to use.
I hope this helps.
Dave

[shred]

I found 3/4" solid graphite pencils at a local art store.  That worked well for my little stirling fan.  Maybe not the best grade of graphite, but plenty slippery.

[rleete]

Good idea.  Thanks for the tip.

[sorveltaja]

Couldn't resist to put trivial quiz about Ringbom engine(s)... Who was the inventor? When did he patented it? What countries it was patented on?

[NickG]

I can't see the video here but will have a look tonight. Love the concept of Ringboms as there is only 1 crank, conrod etc - mesmorising and make a unique noise.

Stirling engines are great! As somebody said, all you need is a flame, no inlet or exhaust, just two smooth pulses per revolution and hardly any noise ... mesmorising! When I built mine (only built 1) the buzz I got from seeing it run for the first time was 10 fold that of a steam engine! I modified mine to have a water jacket in the trouble shooting phase as I thought my delta T wasn't big enough. But with help from Jan ridders I found the real problem and it will run without the water cooling now, although it runs for a lot longer with it. I just wish I made a much bigger burner as it only runs for about 8 mins on the tiny burner I made! I may modify the base (drill a hole in it) so I can hide a bigger burner under the base and have the wick poking through.

If anybody is in two minds whether to try it and you have a few small steam engiens under your belt, go for it. Study Jan Ridders website though, there are some invaluable tips on there.

Nick

[bogstandard]

Just a quickie  here.

If any of you do ask Jan for one or a few of his plans, please, if possible, make a donation, even if it is only a couple of bucks. Running a site can be a rather costly business when it is coming out of his own pocket. We don't want his site being invaded by even more adverts just to keep it going.

http://heetgasmodelbouw.ridders.nu/index_framelinks_english.htm
 
He is one of the most innovative small engine designers I have come across who DOESN'T CHARGE ANYTHING for all the hard work he puts in. Everything is given freely, not a thing you see much of nowadays, and he is willing to help anyone who has a problem with his engine designs.

Anything we can do to help him keep his site going will be much appreciated by Jan, and all the modelmakers throughout the world he has given so much inspiration and pleasure to.

John

[NickG]

Having spoken to Jan via e-mail a few times, I have to agree. He is such a great guy, I was very surprised when he made time to help me trouble shoot my engine. I will make a donation tonight. Actually, just looked at his website and can't see anything on there, any ideas John?

[bogstandard]

Normally when you ask Jan to send you a plan, he will send it to you by email, and included with that will be a donation link, if you want to participate.

When you see what people are charging for very basic plans on the net, and most times they are copies of other peoples efforts, seeing Jan's plan's is like a breath of fresh air. Unique, well drawn and described, and free technical backup as well. Those cheapskate ripoff merchants should be ashamed of themselves.

I also support another site, but it is French. A fair few very good free plans on here, but I do support him by buying his very good for sale plans. He does do a bit for the loco lads as well. If you really search on the opening page, you should find plans for a garden rail loco that is not just a knock it up job. Reading and understanding French is preferred, but not compulsary, a mouse click can work wonders.

http://jpduval.free.fr/

Bogs

[NickG]

Thanks John,

I like the beam engines from the french site, I actually have electronic copies of those drawings, they look very good. Didn't realise there was all that other stuff too. Nice steam waggon.

Nick