First Sterling Finally Running

Discussion on Stirling or "hot air" engines (all types)
Posts: 4
Joined: Sun Oct 08, 2017 10:27 am

Re: First Sterling Finally Running

Postby mhafele » Tue Nov 28, 2017 7:04 am

Ian S C wrote:That's excellent speed, just needs a bit of engineering to redesign the hot end. If you haven't broken something, you are not really trying hard enough, the hot end probably needs to be brazed into the flange, what is the hot cap made of?
Ian S C
Hot cap is mild steel tube turned down to make it thin. I tig welded the end cap on. I tried to braze the end cap but it got so hot the braze would drip off. Right now I'm trying some jb weld extreme heat crack sealer. So far so good. Seems to be kind of a ceramic material that holds up to 2400F. Looks ugly and slopy though. To do it right I might remake the hot cap flange and tig that on to the tube. Its aluminum now because I had the material on hand. Kind of nervous to tig material that thin.

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Ian S C
Posts: 1983
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: First Sterling Finally Running

Postby Ian S C » Wed Nov 29, 2017 3:56 am

At first I made hot caps from solid stainless steel, bored out in a cup shape, the displacers were made in a similar way but from mild steel. Newer motors have the hot cap made of thin walled stainless steel tube (0.010"/0.25 mm or less), with the end TIG welded in place, and a mild steel flange brazed on the hot cap, and an aluminium plug held in place with high strength/ high temperature Loctite. I'v got a tame TIGger who dose the welding for me, some of the displacers I made hade a thickness of 0.007", he didn't like that.
Below is one of the hot caps made from solid, it has an internal thread to screw onto the rest of the cylinder of a BETA motor.
Ian S C
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