Hot Cold Ratios

[ElecTech]

Here are the finished spec's I ended up with. I planned to use the glass cylinder and found 32mm test tubes I ordered were .005-.006 out of round. I didn't want to order a long stick of boro. The replacement cylinder and lower section are titanium.

Graphite piston, Ball bearings in the conrods and dual in the upright support.

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[Ian S C]

I'd try for some stainless steel for the bolts would be the best, the centre part, ie., from say 1/4" from the bottom, to a similar distance from the top, thin it down (if the rods are 1/4" dia, thin it to 1/8"), this will slow heat conduction.
What sort of bearings do you have for the crankshaft, ideally the bearings, ball or plain should be spaced as far as possible to eliminate the see-saw effect induced by the reciprocating motion of the cranks, if you look at mine, there are two bearings, one just behind the fan, and the other between the two cranks. Ian S C

[ElecTech]

Hi Ian,

The support post is out of 1/2" plate and there are (2) 1/2"ODx1/4"ID ball bearings carrying the crank loads. No noticeable seesaw effect.

Time will tell if I need to change out the tie-rods. The ambient temp saturation atop the fireplace insert may expedite that requirement.

Crankdwg.JPG (17.98 KiB) Viewed 2710 times