Hi Russell,I know the problem, had it myself with water pipe, started boring and it popped open, V’ed it out and a run with the arc welder, the engine is running ok, it was the power cylinder. If your OK with gas welding that would be good.The “Ventolin” canister should work although not ideal, I’m just picturing it, the ideal lenght is approximately 3 x the diameter. Another similar size cylinder is one of the old aluminium starter cans for fluorescent lights. Another one is old electrolitic capacitors,they come in all sorts of sizes. As long as the gap is’nt much more than 2mm all round it should be ok. There’s another thread a bit farther down and 3 or 4 of us get on there and anoy each other-tell each other how were’r getting on, drop in anyway,see ya mate. Ian S C

I did this model some years ago, and it worked (and is still working) a treat. This is indeed a first class plan. The diameter of the displacer and its cylinder are not so critic as long as the gap between them is kept at about 1 mm. The displacer came from a Hupmann cigar aluminium tube and I did the displacer cylinder to fit, from a part of a steel tube. It was more easy this way since displacer are much more difficult to find (I don’t smoke!) than steel tube, which fill a large part of my workshop. Look also if you can find those large felt pens with an aluminium body, generally replaced now by an ignominious plastic bodyI never had the problem you mention with cycle frame tubing. I was amazed on the opposite by the quality of this stuff, a seamless steel tube. The extremely penetrating noise during boring is frightening and it takes a long time to bore accurately about 100 mm.

About the same plan was republished (Popular Science, July 1965, p106-110,176. & cover picture), the burner being replaced by a mirror to catch sunrays.

I’m very pleased by this engine, which run at 1200 rpm on a simple alchol burner, I can post pictures or videos if you wish.

Best regards

FM

Edited By gedeon spilett on 27/03/2010 22:52:57

Hi Gideon, I have made a displacer an its cylinder out of one piece of steel water pipe, the cylinder by boring, and the displacer by first boring to smooth,placing it on a mandrel, then turning down the outside. Got a friend (not a modeler)who as an engineer developed a solar water heating unit back in the 1970s, he obtained, and still has a hot air engine with a parabolic reflector that he used to demonstrate the power of the sun. I’v run my largest motor with a large fresnel lense. The kids at school can supply all the aluminium bodied felt pens I’d ever need (they use them on white boards instead of chalk and black boards), I’v used one, they are about 16mm dia maybe a little less, but now replaced by stainless steel. I know about the tendancy for boring bars to chatter( screach),if you want a half decent finish you’v got to stop the noise. Mark I went to the show, two chaps from the Historic machinery Club also went, but we did’nt display anything(it was too cold to stand around). Ian S C