Author Topic: A Simple Uniflow Engine  (Read 45801 times)

Offline gary.a.ayres

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Re: A Simple Uniflow Engine
« Reply #435 on: July 15, 2021, 02:06:15 PM »
That's a really interesting design Gary, for the longest time I really had no idea where you were headed with this, and now I see that you had a plan the whole time. :)
Great project and great outcome, nicely done!

Dave

Thanks Dave - very kind of you.

I had a pretty clear view from the start as to where I wanted to go with it, though I may not have explained it very clearly. The one main mid-build change was that I had originally intended it to be symmetrical, with two pulleys inboard of the frame sides and twin brass flywheels. However, the two brass flywheels combined weren't heavy enough so I made one of them into a pulley and made a new and much bigger flywheel out of some steel that I had. The whole frame became narrower (and better-looking) because of that, which was a bonus. It also leaves me with two spare pulleys for a future project, which is nice. Other than that fairly major change it's as per my initial idea.

Cheers,

gary

Offline RichardHed

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Re: A Simple Uniflow Engine
« Reply #436 on: October 24, 2022, 01:32:40 AM »
Hello All.

It has been a while, what with everything that is going on.

Hope you are all ok...

Finally and at last, I have made a start on my second engine. A slightly unusual one, this.

First of all, the 'simple' in the title of the thread refers to the simplicity of the concept of the engine. It does not mean that I think I'll find this build simple.

The design upon which I am basing the working heart of the engine is by Stan Bray. It's 'Clarence - a clapper valve engine'' from his book on building simple model steam engines:



I don't like the sound of 'clapper valve', so I'm describing my version as a 'uniflow', which I believe it is, albeit a simple example of the type. I am taking the basic working concepts and the relative dimensions of the working parts from the book. There, however, the similarity will end - mine will have a very different look, and it will be at least three times the size of the original, which has only a 10 mm bore.

Essentially this engine will be scratch built. I have an overall idea in my mind but I'll let it unfold as the thread progresses rather than set it all out here, particularly as the plan will most likely change as I go along.

I decided to start with the flywheel - or I should say flywheels. I have had these two brass discs in my parts box for some time. They are about 11.5 cm in diameter. Originally I had thought of somehow joining them to make one chunky flywheel, but I have now decided that the engine will have twin flywheels. This, along with my idea for a frame, will have implications for some of the engineering further down the line. For the crankshaft, the bigger of the two pieces of precision ground mild steel is a bit heavier than I would have chosen, but I have it in my shop and I fancy pursuing a 'use what you have' aesthetic as far as possible with this build:



The flywheels will be composite in nature, each having a central boss  made from a separate piece of brass. They will also have a pattern of holes so I had to drill out and bore the centres so that they will fit the small four-jaw chuck which is mounted on my rotary table:



So, a small start has been made.

This will be a fairly chunky engine and it will need a fairly powerful boiler to run it. More of that later...

I can't find where you got this "Clapper" from.  Also, I can't find the K.N. Harris book.  Do you have an exact name?


 

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