Moriya stirling engine fan build

[Technical Ted]

It was around a year ago I was reading on this list posts by @rmac about his fan build and I got the itch! He was nice enough to give me his Fusion 360 model and that was fun to play with. Well, about a month ago I decided to scratch that itch and make it!

Did just a couple things a little different like we all do when we make our versions of models. Made the displacer out of a solid piece of stainless steel; the cylinder and end all one piece. Made the hot end out of a solid piece of steel so cylinder, end and flange all one piece. No need for silver soldering either of this parts. Got my Prusa 3D printer into the act making the fan blade. Brass bearing inserts for the connecting rods. I trepanned the lightening recess in the displacer piston end on my lathe. Turned out very well. Trepanning is always a little nerve racking especially when using a fairly long, narrow cutting tool. The 1/4" diameter stem wasn't an issue at all as there is plenty of clearance between that OD of it and the inside of the recess so I could get the tool block right in there keeping the tool as short as possible. I also used Dykem to check and make sure the tool wasn't touching where it's not suppose to touch.

Fun project.

Edit: Forgot to give credit to Dr. James R. Senft for his design and drawings.

Ted

[NP317]

Nicely done.
Thanks for sharing.
RussN

[rmac]

How about that! Looks like a Moriya fan to me.

I like the brass bearing inserts.

How thick did you make the displacer walls?
Can you post a picture of your trepanning tool?
And what material did you use for the gland? It doesn't look like brass or bronze in the picture.

-- Russell Mac

[Technical Ted]

I like the brass bearing inserts.

-- Russell Mac

Making the split bearing for the displacer connecting rod was enjoyable. I needed to cut/face a piece of square brass stock and clamp the two halves together before lining them up in my lathe. The split had to be right on center. All dimensions had to be close tolerance. Turned out very well.

How thick did you make the displacer walls?

-- Russell Mac

To tell you the truth, I don't actually remember the exact thickness. From the drawing, the designed thickness was 0.047" but I went below that. I think it ended up between 0.020" - 0.030". I did the bore first and then light cuts on the OD. I know the end wall thickness was right around 0.020". I wanted to keep the weight down.

Can you post a picture of your trepanning tool?

-- Russell Mac

Here are pictures of my tool and I put it back in the holder so you can see the setup. First, it's best to start off with a quality tool bit. You need to have everything as short and ridged as possible. Make sure there is clearance (the tool gets narrower towards the shank). This can be double checked when in the lathe using a test indicator as shown in one of the pictures. The tool needs adequate clearance on the sides as well. Doesn't take much on the inside of the recess, but takes quite a bit on the outside. The cutting edge goes right on center and it NEEDS to be the only thing on the cutting tool that touches the work piece. I marked the tool up multiple times with Dykem to check for rubbing... which would have lead to big problems. When I saw a section rub, I took the tool to the grinder to grind a little more off. I used lots of cutting oil and stopped to clear out chips frequently. I took my time and all turned out very well.

And what material did you use for the gland? It doesn't look like brass or bronze in the picture.

-- Russell Mac

I used a piece of cast iron for the gland since it makes such a nice bearing material and is somewhat self lubricating. I had a piece left over from the 3, yes three, Jeroen Jonkman Stirling 60 Engines I made a few years ago. I roughed the OD and drilled/reamed the ID first. I super glued it to a mandrel to finish the OD to make sure it was perfectly concentric.

Ted

[rmac]

Thanks Ted, for the extra info.

[Technical Ted]

If interested, here's a short video of it running on my stove:

https://youtu.be/6Y7Dp2dOQiA

Ted

[rmac]

If interested, here's a short video of it running on my stove:
https://youtu.be/6Y7Dp2dOQiA

Ted, looks like your Moriya fan is a winner, but your other engines are just stunning! Have you built others besides these?

-- Russell Mac

[Technical Ted]

Ted, looks like your Moriya fan is a winner, but your other engines are just stunning! Have you built others besides these?

-- Russell Mac

The only other one I made was a simple wobbler that runs off a few pounds of air pressure. My first build.

Yes, the Jeroen Jonkman Stirling 60 Engines are beautiful things! When I first saw one I knew I had to make one. Ended up making three of them. It's hard to tell in the video, but the middle one is running at less RPMs than the others. That one was the first one I made and I learned a few things making it that helped with the next two. It's very calming listening to the one I made for my wife running on the mantel. Kind of like listening to a stream running... The boys love theirs too!

Ted