Another Simple Hot Air Engine

Quote from: Minh Thanh1/ I’m going to remove the colored section behind the displacer.
2/ I  make the displacer cap as shown in the picture; it’s simple—no glue or welding required. You just press it on and use a pointed tool to crimp the outer edge onto the cap's rim—doing this at just a few points ensures a durable hold. I’ve used this method often when making displacers.

Thanks again. I've already removed the area in (1) as I'd made a mistake in the drawing and the displacer would have hit the guide bush so I've removed that completely and closed the end gap to 1.5mm on the plan but I'm still adapting the design to suit materials that I have. One thing I noticed when looking through my photos of various engines is round water jackets. This would be much easier to make and fit than a cuboid tank and I already have some suitable material Your idea for a crimped cap is certainly interesting, I think I need to experiment with that - do you have a photograph?

You don't need to experiment with it, as all my Stirling engines use that same method 
I don't have detailed photos, but you can see a picture of the completed  . , It's just slightly different where I cut the groove.
Regarding the power output—yes, it is low—but if factors like friction and airtightness ...are "good enough" , the engine can perform some interesting tasks. This is a Stirling engine I built five years ago; it has a power piston with an 8mm diameter.

  https://www.youtube.com/watch?v=O-hfsQfuBlI

Quote from: Minh ThanhYou don't need to experiment with it, as all my Stirling engines use that same method 

I meant experiment with making it, not test how well it works That's quite a set up you have in the video 

It is simple:
Finish the outer and inner diameters and cut the grooves.
Then, machine the parting line (shown in red), leaving a small amount of material—about 4 or 5 mm. Next, reduce the material thickness as much as possible, down to about 0.3 or 0.5 mm.-and continue ...(green) . You might be able to make the cut in a single pass, depending on the rigidity of the lathe and the cutting tool.