Stirling '60'

[Technical Ted]

Sorry, should have specified... it's LocTite 620.

https://www.henkel-adhesives.com/it/en/product/retaining-compounds/loctite_620.html

Ted

 

[Clockman]

Hello Ted,
Following your advice, I made a new displacer using Loctite instead of solder. I used Loctite 270 rather than 620 as the 620 was extremely expensive and the much cheaper 270 also had a high temperature rating. It was much easier to put together using Loctite rather than solder!
I also made a new bearing out of cast iron. It was the first time that I had machined CI and found it a nice material to work with. I reassembled the engine and applied oil to the pivots and a touch to the displacer rod. The tea light was positioned at the height specified in Jonkman's notes. (When something doesn't work at first, then that is the time to read the instructions!).
I lit the tea light and after a few flicks of the flywheel the engine sprang into life and rapidly accelerated to my great delight. It ran for about 20 minutes without any problems. To test whether or not this was just luck, I stopped and started the engine several times without any difficulty. A great relief.
The engine has been in "the rough" and working on a test rig so far. The next step is to strip it down and finish and polish the brass and make an attractive stand for it.
Once again, many thanks for your advice Ted.

Best wishes,
Clockman

 

[Technical Ted]

Fantastic! That's great news! I know how frustrating these things can be at times...

I think it probably depends on the quality of the tea candle (because of make-up, some burn hotter than others), but after the initial break in I found that mine ran best with the candle way down low and with a very short wick. So the tip of the flame is probably 1" or so away from the test tube. Two things happened when I had a longer wick and a closer flame: 1- the test tube would soot up. 2- after running a while at high speed, the engine would slow down and even stop. This is speculation, but I think that maybe the whole body got too hot and I lost the temperature differential needed between the difusser and the power piston required for the engine to run. Once allowed to cool, I could light the candle again and it would take right off at high speed again. So now, I have the candle holder as low as it will go and trim the candle wick with a pair of finger nail clippers so it's very short. All three of the ones I made run best this way and don't over heat and stop. I have an optical tach and the engine I checked ran at 720 RPM this way. Just something for you to keep in mind.

Another thing to keep in mind. If you find the need to continue to put oil on the difusser shaft, this can cause the power piston/cylinder to soot up and could cause enough drag so that the engine will not run. The 1st engine I made, the hole in the bearing was not concentric on the far end from the drill wandering off center in my lathe. I had to oil that fairly regularly so it would run. Then, it quit running completely... I found soot had built up in the power piston/cylinder from burn oil. Once cleaned out it ran fine again. This was when I made a replacement bearing for that one. This cured the need for oil.

Please post pictures when you are done!

Ted

 

[Ken Ratcliffe]

Hi - your experience sounds soooo similar to mine (even down to I normally make clocks, but gave a Stirling 60 a go as first engine). I too eventually got it to run as well after almost throwing in the towel. On the displacer question, I ended up threading it and using Loctite thread bond. Worked OK. I am going back to a clock (Congrieve) for a while now.....but will keep an eye on the posts here for next engine project

 

[Clockman]

Fantastic! That's great news! I know how frustrating these things can be at times...

I think it probably depends on the quality of the tea candle (because of make-up, some burn hotter than others), but after the initial break in I found that mine ran best with the candle way down low and with a very short wick. So the tip of the flame is probably 1" or so away from the test tube. Two things happened when I had a longer wick and a closer flame: 1- the test tube would soot up. 2- after running a while at high speed, the engine would slow down and even stop. This is speculation, but I think that maybe the whole body got too hot and I lost the temperature differential needed between the difusser and the power piston required for the engine to run. Once allowed to cool, I could light the candle again and it would take right off at high speed again. So now, I have the candle holder as low as it will go and trim the candle wick with a pair of finger nail clippers so it's very short. All three of the ones I made run best this way and don't over heat and stop. I have an optical tach and the engine I checked ran at 720 RPM this way. Just something for you to keep in mind.

Another thing to keep in mind. If you find the need to continue to put oil on the difusser shaft, this can cause the power piston/cylinder to soot up and could cause enough drag so that the engine will not run. The 1st engine I made, the hole in the bearing was not concentric on the far end from the drill wandering off center in my lathe. I had to oil that fairly regularly so it would run. Then, it quit running completely... I found soot had built up in the power piston/cylinder from burn oil. Once cleaned out it ran fine again. This was when I made a replacement bearing for that one. This cured the need for oil.

Please post pictures when you are done!

Ted

 

[Clockman]

Hello Ted,

This is my completed engine. I thought that it would be fun to make it look like the sort of thing that a Victorian gentleman with an interest in science would have in his study to show his like-minded friends. Hence the faux-marble plinth with brass ball feet and the addition of a little colour to the frame and flywheel.
You may have noticed the additional cooling vane clipped to the power piston. I found that the piston heated up quite quickly and the temperature differential was lost after about 11 minutes. Adding the vane more than doubled the running time. I'm pleased to say that the engine runs without the need to oil the displacer bearing now that it is made of cast iron.
My engine can be seen running on the youtube link
I think that as I have quite a lot of material left over I will make another one - but do it better this time!

Thanks again for your advice, which was invaluable.

Clockman

 

[Technical Ted]

Looks awesome! Love it! Looks like the candle holder could double for a gear in one of your clocks!

Great job! If you do build another, please post more pictures.

Ted

 

[Clockman]

Hello Ted,
I was planning to make another Stirling 60 but got interested in Low Temperature Differential engines. I found a book by Jim R Larsen "Three LTD Stirling Engines You Can Build Without a Machine Shop" His Number 2 engine looked interesting so I thought that I would have a go at building it. It was a novelty working with aluminium, acrylic plastic, brass and a wide range of adhesives. I originally used ball races but this was a mistake because, to my surprise, they had too much friction. I reverted to plain steel on brass bearings which worked OK. The main problem was with getting an air-tight chamber. My first go leaked and I was puzzled as how to find where the leaks were. But I remembered how my plumber searched for gas leaks using soapy water on the pipe joints. Painting soapy water on the seams of my chamber and then blowing into it created bubbles which quickly showed up where the leaks were. They were then easy to fill.
I mounted the finished engine on a base board with levelling feet and a 60w spot bulb as the heat source.
It is seen running on the youtube site below. It was fun to build (if not particularly challenging from the machining point of view)


Best wishes,
Clockman

 

[Technical Ted]

Hello Ted,
I was planning to make another Stirling 60 but got interested in Low Temperature Differential engines. I found a book by Jim R Larsen "Three LTD Stirling Engines You Can Build Without a Machine Shop" His Number 2 engine looked interesting so I thought that I would have a go at building it. It was a novelty working with aluminium, acrylic plastic, brass and a wide range of adhesives. I originally used ball races but this was a mistake because, to my surprise, they had too much friction. I reverted to plain steel on brass bearings which worked OK. The main problem was with getting an air-tight chamber. My first go leaked and I was puzzled as how to find where the leaks were. But I remembered how my plumber searched for gas leaks using soapy water on the pipe joints. Painting soapy water on the seams of my chamber and then blowing into it created bubbles which quickly showed up where the leaks were. They were then easy to fill.
I mounted the finished engine on a base board with levelling feet and a 60w spot bulb as the heat source.
It is seen running on the youtube site below. It was fun to build (if not particularly challenging from the machining point of view)


Best wishes,
Clockman

That's awesome! Watching and listening to that would put me right to sleep! Neat project!

I took a break from model making and recently bought a KO Lee tool and cutter grinder as well as a Rhodes shaper. I just made an "Impossible Dovetail Puzzle" on the shaper.

I'm sure I'll get back to model making soon!

Ted

 

[Clockman]

Hello Ted,
I must admit that I didn't know what a Rhodes shaper was until I looked it up on the the web. It certainly is a massive bit of kit! It made a very nice job of the Impossible Dovetail Puzzle ( which was something else I had to look up to find out how it works).
Thank you for your kind comments and good luck with your model making.
Best wishes,
Clockman

 

[mike-oz]

Nearly made all parts just need to finish the connecting rods.
What holding device did you use to cut the slots in the connecting rods and keep them parallel?
Regards
Mike