Two Questions.

[Bob Hornby]

I am designing and building a simple "Cup of Tea" engine. The displacer diameter is 95 mm internal. The height is 20 mm and the displacer is 9.5 mm thick with a 10 mm stroke.The power cylinder will be 6.5 mm diameter with a 12 mm stroke. The power cylinder and piston are not yet made so I can change these. I can also change the stroke of the displacer piston. My progress so far is to make the displacer cylinder and top & bottom plates.
So, my questions are -
1. What clearance should I make between the displacer and cylinder (on radius)(I am thinking about 2 mm) ?
2. Is the ratio between the displacement of the displacer and the power cylinder OK ?
Regards Bob

[Tom Booth]

That is all about the same as this engine, except the piston diameter, which, on this engine, is a bit bigger at about 9.5mm, and the clearance around the displacer is slightly less, about 1.5mm if that's any help.

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[Bob Hornby]

Thanks Tom. that helps a lot giving me confidence that I am on the right track.
Bob