For all you would-be machinists out there and experienced engineers as well, we have sourced many Free Plans for Model Steam Engines from around the internet.
Some are beyond the scope of novice builders, like fully complete locomotives that take years to construct.
Other simpler engines like wobblers (oscillating engines, whether steam or air driven) can be done in a few weeks without too much trouble, although these are readily available in a completed working state from Amazon and many other sources.
If you are into self-assembly, these same or similar engines can be found here at PM Research who offer fully machined or non-machined engines for you to build and as a bonus, many of them work well on boats.
However, as we’ve not built all of these engines below from plans, we cannot guarantee the plans or descriptions are complete.
The best bet is to download any pdf’s that take your interest and decide from there.
To make life easier; we have arranged them into different categories to help you choose your downloads – just click the blue links and you can then download your free pdf.
Quick Links to Categories Below:
Free Beam Engine Plans
The image below shows the type of steam engine meant by Beam Engines – for those who are unsure.
The drawback initially was they relied on air pressure to force the piston down, so they had to be huge – 5-foot diameter pistons and more, along with strokes to match – with very poor seals because of poor manufacturing processes back then, meant steam had to be drawn into the cylinder at low pressure (boiler containment pressure problems back then were common with many boiler failures) and when the piston was highest, cold water was sprayed into the captured steam to condense it to water, causing a vacuum below the piston.
Later versions, once boilers became more reliable and pressures were raised, meant steam pressure could be used to drive the piston, meaning smaller cylinders could be used and the motors could be sped up a little.
Not exactly authentic, but this very inexpensive, snap-together water pump in the guise of a model beam engine encourages kids to become more constructive and leads them on to explore the past, especially the steam era.
Free Boat Engine Plans
In the case of boat engines, you can easily use any model steam engine for a power source providing it is big enough for the hull and you can also get a boiler in there.
Many operators have to use remote-controlled servo-assisted rudder steering with these models for obvious reasons.
Oscillating engines, being lower in height, have the benefit of another safety measure, owing to the spring pressure holding the cylinder against the main block, allows the cylinder to lift away from the block to relieve any excess boiler pressure.
Also, if gas is used as a fuel, that can be regulated using a servo too.
Launch engine — Medium build
Marine Engine — Easy build
Twin cylinder oscillating boat engine — first-timers build
Compound Condensing Engine (1) — very difficult
Compound Condensing Engine (2) — very difficult
This one is a 90-degree twin-cylinder model constructed of brass with everything brazed. It has its own cylinder lubrication system – one of the well-proven displacement lubricators used on smaller live-steam engines.
On top of this, a single servo can control steam flow and pressure to the engine as well as forward and rear direction.
On top of these, although not free, we recommend Stan Bray’s ‘Model Marine Steam’ book (above – just click the picture or this green section) where you are taken through the construction of a model steam vessel from start to finish showing detailed plans of different steam engines used to drive boats, some simple, others complicated, along with hull construction and ancillary fittings… Well worth a read if you are into building your own steam-driven watercraft.
Free Boiler Plans
Model boilers – general boiler guide
Pop Science Boiler 1949 — Easy build
FLASH – A very simple flash tube boiler — easy and cheap to build
Free Hot Air and Stirling Engine Plans
Hot Air and Stirling Engines run using a sealed system of air where one end is heated and the other cooled, either naturally or by being immersed in a liquid. Between these ends is a displacer piston to move the air around, pushing the cooler air to the hot end and the hotter air to the cooler end.
Sounds a bit complicated as this gif does not show exactly what is written, but by using two pistons, one the power piston and a second as a displacer piston, both linked to a crankshaft, this air movement can achieve rotation of a crank by using very little heat at the hot end.
Obviously, Hot Air Engines do not produce a great deal of power unless they are scaled up considerably with great heat applied to the hot end, although they were used in the early days for trans-Atlantic shipping, using seawater for the cooling and coal for the necessary heating.
This diagram is very basic in that it does not show the air transferring from the cool end to the hot end, but as you will see, the cylinders need to be set at 90 degrees apart for this process to happen efficiently.
There are 4 variations on the principal of hot air engine building and design, some very simple and some extremely complicated, but the ones below are the simpler versions.
Air Cooled Hot Air Engine — a relatively easy build
Hot-Air Engine — a simple build
Live Steam Stirling — a bit of a difficult one, this.
Free Steam Loco Plans
For most of these loco’s, be prepared for the construction to take ages to complete, especially if you are manufacturing the parts yourself as many parts are so fiddly you’ll need a good magnifying glass.
However, many of these engines have castings available from different suppliers throughout the world, mainly in the UK.
Ajax Model Engineer 1947 — a very simple first-timers loco.
Newbie Locomotive — Large pull-you-round loco – medium difficulty – American made.
JPDuval Steam Train — A bit on the difficult side, this one, as are the remainder below.
Rose (loco for beginners)
Free Steam Engine Plans (and other) Oddities
Free Wobbler or Oscillating Engine Plans
Free Turbine Plans
Micro-Steam Turbine Car — super easy
Model Steam Turbine Design – super easy
Free Vacuum Engine Plans
Not to be confused with Stirling Engines and sometimes known as flame lickers, these were the first type of steam engine available, where low-pressure steam was drawn into a cylinder, then allowed or forced to cool, meaning the piston would be drawn along the stroke by a vacuum before the cycle was repeated.
Present-day ones are much simpler and do away with having to stoke up and raise steam pressure in a boiler, but draw hot air directly from a flame into the cylinder which cools naturally and does exactly the same thing, although because the cooling is slower, they produce very little power.
Owing to the lack of speed regarding quick-cooling, these Vacuum Engines tend to rev relatively slowly, plus they also need a good-sized flywheel to continue the crankshaft momentum.
How about Building the Piston Valve Engine???
There… That should keep you busy for a while…
More to come in the very near future…