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| Manxmodder:
Bertie,nice to see you have not given up on it,you're sure to get a runner eventually. I really do like the look of it with the re-purposed components and gearwheel crank. :thumbup: ......OZ. |
| vtsteam:
Bertie, nothing's ever for sure, and you may surprise me yet, but I still think you have too much mass (and therfore friction) in the basic design for a really low temperature differential Stirling. I think it will work fine with more temperature differential, the only limitation being the material used for the displacer, and how much heat it can handle. Balsa can handle a higher temperature than foam or other plastics, and a hollow aluminum displacer can handle even more, though heat transfer along the sides of an aluminum can favors a longer displacer and cylinder. The length will determine how long it runs without the whole engine heating and slowing down. The shape and materials of a Stirling engine are closely related to the temperature differential chosen. It's a great looking engine, I think, and I'd love to see it run. :thumbup: :thumbup: :clap: :clap: |
| bertie_bassett:
managed a few more hours on it today firstly I cleaned up the balsa displacer, and glued in a M3 nut on each face. these are to hopefully allow things to stay square and secure. gluing these in was a right arse as iv made the displacer hollow with the faces only being 1-2mm thick, but I got there in the end :) next job was to turn up a small brass collar for the base of the power cylinder. this is mostly cosmetic, but also allows me to get more silicone round the base for better sealing ( there was a small leak last time) then everything was re-assembled and siliconed up. currently waiting for it to dry |
| bertie_bassett:
well after a few jobs and writing the last instalment I got bored/impatient so decided the silicone must have gone of and it was time for a test run. here the result! started running at 18:25 on a fresh cup of hot water from the kettle and stopped at 18:45 not bad for an engine with the wrong materials and too much mass :thumbup: on close inspection there are a few issues still with the displacer though, namely: 1- there is a slight rubbing noise form the displacer seal 2- the displacer is on slightly crooked 3 - the displacer is just catching on the base, just enough for it to stop momentarily, but not enough to cause binding ( there is a bit of slop in the clevis pin which is helping me out here ) 4- the balance could be improved ( for the moment iv just stuck an M6 nylock nut on with double sided sticky tape) oh and its still going backwards :doh: I believe if the displacer wasn't crooked then it wouldn't be catching, but being as its a runner i'm not going to fiddle with it anymore. its going to be a present for my dad's birthday next week so don't want to risk it not running again. all that now left to do is to make up a nicer balance weight ( am thinking brass letters with his initials) and to make up some small brass covers for those bearing mounts. then its just going to be polishing! |
| Stilldrillin:
Nice one Bertie! :clap: :clap: Learning the necessary finesse, for these frustrating engines, is really character forming...... :bang: :bang: Well done! :thumbup: David D |
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