Stirling Engine : Laura

[Brian JohnParticipant @brianjohn93961]

I am using these :

**LINK**

I call them roller bearings but they often get called ball bearings on ebay. I have no idea what type of bearings they actually are. They are used in roller skates and in-line skates.

[Neil WyattModerator @neilwyatt]

Roller bearings are wider and use little cylinders instead of balls.

Neil

[Ian S CParticipant @iansc]

They are ball bearing races. Most of my bearings are salvaged from old VHS video recorders, if you get enough machines, you can get a range of sizes from 3 mm, to 6 mm bore, along with little shafts, and bits and pieces. Ian S C

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Brian John on 29/06/2016 11:11:47:

I call them roller bearings … are used in roller skates

.

I suppose that's logical, in itself, Brian; but I think it advisable to stick with the standard engineering terminology.

MichaelG.

[AjohnwParticipant @ajohnw51620]

Ian's being correct but ball races will do, ball bearings are just the balls. Roller bearings come in two main forms plain ones with rollers and shells that do not have an internal a taper and taper roller bearings. Then there are angular contact types which are a little like ball races but only take end thrust from one side. Magneto bearings are very similar.

John

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[Ian S CParticipant @iansc]

The only roller bearing that I have used is the needle roller bearing that I fitted in the bell crank/yoke in my Ross Yoke ALPHA motor because I thought that it needed the extra width for sability, and the low profile was also helpful. The other two bearings at the end of the con rods are 4 mm bearings from a video machine. Ian S C

[Brian JohnParticipant @brianjohn93961]

All is going well and the bearing lock seems to be holding up. I have experimented with different D piston diameters and found that 12.7mm was very good. As luck would have it, that stainless steel D piston I made up some weeks ago is exacly that diameter so I decided to give it a go. It ran very slowly at about half the speed of the aluminium piston ; I think it is too heavy.

I noticed that the thread is badly rusted out. It has only been sitting in a cardboard box and I have never seen silver steel rust so quickly. Is this something to do with silver steel being in contact with brass which is in contact with stainless steel ?

Edited By Brian John on 30/06/2016 12:11:29

Edited By Brian John on 30/06/2016 12:12:37

[Ian S CParticipant @iansc]

Silver Steel/high carbon steel in a place like Cairns with it's high humidity, will if left un protected with oil rust quite quickly, a wipe with an oily rag before it rusts is the way to keep things shiney. Yes the displacer should be as light as possible, The relative weight of displacers decreases as they get bigger.

[Brian JohnParticipant @brianjohn93961]

I had enough bits and pieces left over to build a third Stirling engine but using a brass flywheel from PM Research rather than the supplied cast iron flywheel that comes with the kit. This engine has been running well for over three weeks now but this afternoon I decided to remove the flywheel to give it a proper polish with 1500 and 2000 grit. When I initially machined this flywheel I did not give it a final polish with the wet and dry.

In the back of my mind was the thought : ''Leave it alone…it is running nicely now'' ….but no, I ignored the warning and went ahead and polished the flywheel. Upon reassembly I found an unexpected problem. The whole axle/flywheel assembly keeps pulling to the right and this pulls the work piston crank (on the LH side of the engine) in contact with the LH bearing support hence stopping the engine. I have spent all afternoon making adjustments to try and fix this but nothing has worked. I am now out of ideas.

Any suggestions ?

Edited By Brian John on 27/08/2016 10:08:04

[HopperParticipant @hopper]

A tiny little spacer washer in there so that when the crank moves over it contacts the washer which tranfers the load to the inner race of the bearing which rotates?

[Brian JohnParticipant @brianjohn93961]

Okay, that should do it. I will have a go at making a small spacer washer tomorrow.

I do wonder why it is giving problems now whereas before it was flawless in its performance ? This is why I am going back to steam engines : I will leave the flame eaters and Stirling engines to more patient people

Edited By Brian John on 27/08/2016 12:16:53

[Gordon TarlingParticipant @gordontarling37126]

Is it possible that you've re-fitted the flywheel the wrong way round?

[Brian JohnParticipant @brianjohn93961]

Thank you Hopper : that seems to have worked. I made a five 6mm ID X 8mm OD bushes of various widths and the 2.5mm wide bush gave the best fit so I went with that. I have run the engine four times now and everything seems to be holding in place. It was a good exercise in working close to the chuck !

Gordon : would not the engine run no matter how the flywheel was fitted ?

[Gordon TarlingParticipant @gordontarling37126]

Brian – I was thinking that perhaps the bosses either side of the flywheel may not be exactly the same width, causing the flywheel to be slightly offset if fitted the wrong way round.

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