Before I made model ships I made model cannons and before that I made model steam engines and boilers. This post will show some of the engines.

The steam engines all work on steam or compressed air, and are exhibited once or twice each year. Some are scratch built and some are built from castings of bronze or cast iron.

The first one is a 1:8 scale engine which was designed by Richard Trevithick and built it 1803. It was the first steam engine to run on "high pressure" steam (50psi). Before then there were steam engines which worked at less than atmospheric pressure by condensation of steam. Trevithick's engine was vastly more efficient and compact. The version of his engine was designed to power a dredger which was used to deepen the Thames River at London. The cylinder was double acting and the steam was directed to each end of the cylinder by a rotary valve. The cylinder was located inside the boiler, for heat conservation efficiency, but that location was ultimately discontinued.

This model runs on steam produced by propane, but the original used coal and/or wood. The model can be seen running on steam at johnsmachines.com

The pressure gauge and water level glass were not on the 1803 original, but were added to the model in order to get the boiler certification.

Currently it sits on a bench in my kitchen, with decorations added by my wife.

Edited July 11Jul 11 by JohnofOZ

p.s. this one was scratch built.

This model steam engine is based on a water supply pump from the 19th century. It was made from cast iron castings and plans. It took me about a year to make. The steam cylinder is double acting ( the steam pushes alternately from each end of the cylinder). The water pump is a separate unit powered by a rope belt. (not shown). The large flywheel rotates slowly and majestically.

Some of the unmachined castings are shown in photo 2 and 3.

The complete model in photo 1 is quite heavy at 20+ kg.

The 4th photo is the beam engine and the vertical boiler which I made to power it. The boiler is heated with propane.

John – your steam engines are tremendous!  Having them both look incredible and work is really challenging.  I went to Cabin Fever, an annual miniature engineering meeting in Lebanon, PA last winter.  They had around 100 engines like yours running at the same time – it was really impressive.  I left with a PM Models kit of a stationary engine with big plans to learn machining skills by building it.  It is still sitting on the shelf – once I got a better sense of what was involved I decided I should wait until I have more time.  Your models are way more complex than the kit I got. You clearly are a really talented machinist.

Dave

Dave, thank you.

Buying a kit of plans and castings was exactly how I started. Plus joining a model engineering club and tapping frequently into the knowledge of other model engineers. And making mistakes and learning from them. Often repeatedly.

So open up your kit and get going! One part at a time. If I (a retired doctor) can do it, anyone can.

This is the most difficult engine which I have built. It took me 3 years, with several long breaks to recover my sanity.

It is a 3 cylinder marine steam engine, triple expansion, double acting. It runs on steam at 100psi, and would probably run more efficiently at 120+psi.

It is based on the engine of a large ferry from Sydney harbour, which was sunk during a Japanese midget submarine raid in 1942 (look it up... SS Kutabul, possibly sunk by friendly fire from a US heavy cruiser).

Made from plans and bronze castings.

The build details are on johnsmachines.com

The last shot is the castings which the engine was built from.

I am a crap painter which is why I usually leave the metal bare.

Would you consider a steam boat at some point? Mixing the hobbies together a little?

Your work is just incredible. I'm always in awe of skills like this.

James, thankyou, but I feel that I am still a model shipbuilding newbie and just making some progress with my semi-scratch 1:72 HMS Bellerophon. But anything is possible. John

Edited July 11Jul 11 by JohnofOZ
Photos of ship model under construction deleted.

Hello John, and welcome to the forum from up in Sydney.

Your engines are magnificent, although I should advise you that a steam engineer would probably correct you on the ferry engine from, 'triple expansion engine' to 'three pot up and downer'. 😀

John

It's a blessing that you left it unpainted, looks more interesting that way!

What exactly made that last engine so challenging as compared to your other engines?

An interesting project would be a scratch-built ship with one of your working steam engines for a Saucy or an African Queen model.

Just now, RichSloop said:

An interesting project would be a scratch-built ship with one of your working steam engines for a Saucy or an African Queen model.

That boat was always something I aspired to.

On 7/13/2026 at 12:23 AM, Mike Y said:

It's a blessing that you left it unpainted, looks more interesting that way!

What exactly made that last engine so challenging as compared to your other engines?

Sorry Mike, I thought that I had answered your question but I don't see my response so here it is....(must have forgot to hit enter)

The triple expansion engine is much more complex than all of the other engines due to the 3 cylinders of different diameters, each requiring its own timing, and the inaccessibility of many fasteners and particularly the middle cylinder. Also it has a suction pump and water pump and a condenser. PLus I was a relative newbie to steam engines, having built only one prior to the triple. And the plans were pretty basic, with minimal advice how to accomplish some very complex (for me) machining. And this was my first solid crankshaft. But I did manage to make it on my second attempt.

Full details of the build are on my blog at johnsmachines.com but you will need to search 2014-2017 posts to see everything.

John