Stirling Engine H8101 Grizzly

Hello, as I have now made most of the parts for the Stirling Engine H8101 from the drawings on the Grizzly web site, I need the dimensions for the hot cap which are not shown.

I contacted Grizzly and asked to purchase the part, but a minimum of $200 and a minimum 70lb shipping weight. I also asked the technical department if I could have the dimensions but they refused. They suggested if I knew someone in the USA they could post the part to me.

I understand that the dimensions for hot and cooling pistons are important, I have made the 13mm cooling cylinder and piston. If anybody has the dimensions for this hot cap it will be much appreciated.

Thanks for any replies

If you know the stroke, you can probably work it out by looking at other designs. From memory, swept volume (stroke x piston diam.) of the displacer piston is about 1.5 times the swept volume of the power piston. Some engines go as low as 1.2, others as high as 2.0. But it seems 1.5 is a good rule of thumb. You then need to make the cylinder to have 20 to 40 thou (half to one mm) clearance between piston and cylinder bore and about the same between piston and the end of the cylinder at each end of the stroke.

Otherwise, if you want to buy Grizzly's hot cap, there are numerous mail forwarding agencies in the US who charge basic air freight plus a small service fee. Still not cheap, as US postal prices have gone stupid high recently, but you would certainly get a lot of change from $200! If you google "mail forwarding agencies USA" you will find some good options.

Edited By Hopper on 17/05/2016 02:19:40

If SIEG HAE01 kit, then try this:

HAE01-Part 21:

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HAE01-Part 45:

Thanks for your replies on this, I didn't really have clue on the displacer piston being 1mm smaller than the cylinder. It seems obvious now, hot air moved to cooling power piston creating the vacuum.

Can the displacer piston be made out of solid brass, as the drawing shows it being hollow. I have made the power piston out of aluminum as well as the cylinder if thats correct.

It is best to make the displacer piston hollow but sealed. That way it conducts less heat from the hot end to the cold end of the displacer cylinder. Stainless steel is a common choice because of its poor conducting properties.

Aluminium on aluminium for the power piston/cyl is not the greatest combo either for friction or wear. I would think about making the cylinder from steel and the piston from ally, or even vice versa. Or brass for one and steel for the other. A popular choice though is a cast iron piston in a steel cylinder, or vice versa. Lowest friction option would be a graphite piston in steel cylinder, but graphite is 'orrible messy stuff to machine.

With advice given I have decided to make remake the power cylinder with a steel liner and cast iron piston. The drawing and advice given shows a sealed displacer piston. I was to put a minimum vent hole in this as I thought of expansion when hot, am I correct or not. I am grateful for these replies as my questions must seem rather basic as to question on this forum.

I dont know enough about the subject, but I do know that the displacer piston needs to be light. Generally these systems work well when things are light, and, to the best of my knowlege, avoid putting in a vent hole.

Perhaps invest in this book for guidance. Roy Darlington - Author of the book is a great authority on the subject, along with the members of the Stirling Engines Society.

I am sure that the Society will have a stand at the Doncaster Show over the weekend. If you can make it there, I am sure that members of the society will be a great source of information and guidance.

Ketan at ARC.