Attempting to build a Micro LTD Stirling

[Paulie1982]

Hi Everyone,

I am attempting to build a Micro LTD Stirling Engine. It is approx 2 inches (50mm) tall and 1 inch in diameter (25mm). I say attempting because it is quite difficult to make a normal size LTD Stirling, never mind such a small one.

I completed the design phase a couple of days ago and have begun to make the parts. Here are a couple of images of the original design (some parts will probably require redesigning and modification as i begin assembling the engine)





AutoCAD 3D model -







2d dxf file in LazyCAM -






Orange A Frame (on the left) after being CNC'd



Proposed completed engine

[Brass_Machine]

Very ambitious! I like the design a lot.

What is the material for the orange frame?

Have you ever built a LTD stirling before?

Eric

[Paulie1982]

Thanks Eric,

The rendered design (last image) is a bit out of date, as you can see i have the power piston and power cylinder inside the displacer cylinder, i had to modify this design because a) it was decreasing the overall volume of the displacer cylinder and b) the displacer was rubbing off the power cylinder as it twisted slightly during its up and down motion, this caused enough friction to stop the engine.

You can see it in action here, the animation, not the real engine ;). Unfortunately in this animation it is also the old design, with the power cylinder inside the displacer cylinder.

http://www.youtube.com/watch?v=NvKbPEuMRy4&feature=channel_video_title

I've never successfully built a Stirling before, this is the only one i've worked on, i attempted building it quite a while ago and failed, but now i'm reinvigorated and ready to go for round 2

The orange A Frame is made of 3mm thick acrylic sheet, its nice and sturdy and easy to cut.

[raynerd]

Nice one, good luck. What is the power piston material going to be along with the cylinder material?

Chris

[Paulie1982]

Hi Craynerd & Da_Kengineer_Meister,

I think i'll be able to answer the both of you with the same reply -

I cheated slightly with the power piston and cylinder, i bought them from a company called Airpot (albeit with great difficulty, living in Ireland is no fun at all when trying to source any type of manufacturing materials, had to get them in Australia  ). The cylinder is borosilicate glass (i think) and the piston is graphite. They run very smoothly and need very little force. The cylinder i have is 7mm OD with 5.02 ID and 5mm piston, i currently have the piston set at a 4mm stroke from top dead centre to bottom, i'll see how that works.....or doesn't .
If you haven't heard of them you should check out their cylinder & piston sets, they're fairl cheap and definitely save a lot of work.

[saw]

Thanks for showing this video, it's very intressting good luck with construction. 

[raynerd]

Hi Paulie, yes I have heard of them and nearly used them when I made my failed LTD. I did look at purchasing but found they were very ££££ !! Nice work... look forward to more updates.

Chris

[Paulie1982]

Thanks folks, I'm sure i'll be needing your help in the future when i get down to the nitty gritty business of trying to get this lady to run .
Hope you got my message Chris, good luck with the Stirling.

[NickG]

Hi Paulie,

I attempted one after seeing Jan Ridders - I did my own design but failed. I think i documented it on here, can't quite remember. I like your design, looks simple but hopefully effective - that's what I was trying to achieve. I don't think I got the balance of the mass of components right and my machining wasn't up to scratch.

I've re-designed it now on CAD but not got around to building Revision B - it's a few projects down the list.

Good luck

NIck