Live Steam 
Twin Cylinder "Mill" Model Steam Engine 
Fully Machined Kit in Brass, Bronze and Steel 


The horizontal twin cylinder "mill" engine is a simple design, yet retains the basic mechanics of engines which powered factories, workshops and mine pits in the nineteenth century.

NOTE: Pictures are of the finished, assembled and painted model, this listing is for the kit of parts, see picture.

The classic mill engine layout has two double acting cylinders, eccentric driven piston valves and the brass flywheel offers smooth running and is capable of powering a range of accessories, in a variety of roles. The engine also includes triple split bronze pedestal bearings for the crank shaft, tube sliders and a very substantial cast base.

On the twin crank shaft, the cranks for each cylinder are offset by 90° which means the engine will self-start in any position.

The engine will run in reverse by applying the steam (or air) input to the outlet ports. Our Reversing/Throttle Valve (optional extra) will control the direction and speed of the engine in either direction.

The kit consists of precision produced parts each carefully made and checked to ensure ease of assembly and reliability in service.

The cylinder assembly and piston are manufactured from brass and the piston shaft, connecting rods, column screws and valve from stainless steel so are not susceptible to corrosion. The piston shafts passes through an adjustable glands and the steam inlet can be on the top or bottom of the chests.

Detail Specification:
- Type: Tube Slider
- Bore: 14mm
- Stroke: 18mm
- Flywheel Diameter: 56mm
- Valve type: Piston
- Height (excluding manifold): 65mm
- Length: 150mm
- Width: 100 mm
- Weight: 1.7Kg
- Connections: 1/4" x 40 tpi ME

The kit consists of a set of fully machined parts that can easily be assembled using simple tools such as a screw driver, allen keys, pliers and metal file. The parts are mainly unfinished metal and will also require painting, polishing, filing, etc. to achieve the appearance shown in the pictures.

NOTE: The kit is supplied with hex or socket head set screws (as per the pictures), although some screws for ease of installation, have to be socket head screws. Some screws as provided may need to the cut or filed to length to complete the model, contact us if this will cause a problem.

Two of the pictures show the optional Manifold set which combines two inlet or outlet ports together into a single port.

When assembled the engine is fully working and can be run using steam or simply using compressed air e.g. from hand or foot pumps.

To power the engine with live steam, connect it to one of our Model Steam Boilers.


NOTE: The model steam engines and boilers are NOT children’s toys and should not be assembled or operated by children unless under close supervision of an adult.
Name Size Action
Mill Twin Cylinder Model Steam Engine v2 Assembly Instructions 2.64MB Download
Mill Twin Cylinder Model Steam Engine Assembly Drawing 779.52KB Download

Horizontal Mill Twin Cylinder Engine Kit

  • Product Code:HTA2
  • Availability:8
  • £270.00


Available Options


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Tags: Live Steam, Model Steam Engine, Fully Machined Kit, Twin Cylinder Mill Engine