my first stirling engine

[Perry]

Hi there, I was admiring stirling engines for some time already, finally (some months ago) Ive decided to give it a try with Moryia stile engine.

I had few targets :
1. build functional stirling engine
2. to pracitce in building build-up crankshaft using silver steel rod and undersized reames
3. to practice radius machining with rotary table
4. take a brake from my longterm project (2 cylinder IC engine)

just yesterday evening I made first trial start and it was runing for 30 seconds until aluminium powerpiston seized, polished it and second run was simmilar with even worse seizure. so it is operatiolal but definitely not yet finished

some photos of where I am so far will follow

[Perry]

turning the cooling cylinder. Comparing to Moryia Ive decided to stay with cylindrical shape and much larger cooling fins, turning the thin deep grooves was not realaxing job as the aluminum of suitable diameter that I had on hand was radher soft and was sticking to HSS tool oftenly.

[Perry]

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[Ian S C]

Aluminium is not a good idea for a piston (or any sliding part), I don't know what your cylinder is made of, a steel bore would be good, and in this a cast iron piston.  These motors are a bit different than an IC motor, that can have an aluminium piston with rings, and the rings make contact with the bore and the ally piston has enough clearance not to seize, but the Stirling Engine relies on a free fitting, but close fitting ringless piston for minimum friction.
Ian S C

[b.lindsey]

Perry, graphite is often used for the power piston and will work with aluminum cylinders. It's also self lubricating.

Bill

[Perry]

Power cylinder is out of steel with lapped bore. aluminum piston was dry lubed with graphite powder and had very low friction while compression was excelent when tested without heat, however this combo did not survived first heat test. As suggested above, new power piston will be from castiron and if required lubed with graphite powder or MoS2 if I can get powder form.

[Perry]

to cut the friction down, a ball bearing was used also on displacer pistonīs conrod big end.
Ball bearing was installed in to build up crankshaft durring assembly. while brass conrod have a split bigend held by M2 allen bolts

[Perry]

crankshaft consist of 6mm dia silver steel rods and milled mild steel throws. Ive used a press fit assembly ( reamer 5,97 H7) secured with again press fitted 3mm silversteel pins. Iīm pleased with this crank.

hot cap was turned from SS roundstock (lots of wasted material)  with silverbrazed brass flange.

[zeeprogrammer]

Nice family shot. 

Looking great.

[Perry]

One of the main challanges for me was to machine gland with correct tolerance to be sufficiently airtight yet low at friction.

3mm silversteel rod was used for displacer piston rod and 2,99mm H7 reamer to machine hole in to the brass flange, with little graphite powder it seems to work well.

[burnit0017]

Thanks for posting, any info on how the crank shaft is fabricated? Great project, thanks again.

[Kim]

Looking very good Perry!

Thanks for sharing your build.  The Moryia is on my not-so-short list of engines to build too!
Kim

[b.lindsey]

Perry, if you can, please downsize the pictures to no more than 800x600. There is no advantage to the megapixel size since the forum software reduces them anyway so they will show on the screen withouy scrolling. It helps save server space and also downloads much faster especially for those with slower connections. There are numerous free software apps that can do this easily. I use Picassa but there are others as well.

Thanks.

Bill