Boulton and Watt's 10hp Engine

The Model
The Watt's engine that can be built from the kit provided is of the 'Standard 10 hp Engine' type based on
drasvings from John Farey's book 'A Treatise on the Steam Engine' (1827). In the book, John Farey states that he took the measurements from a 1797
working engine in Chelsea. It must be stated at the outset that, because of the scale (approx 1:18) and in the interest of ease of construction, the model
has limitations and is not a fully accurately scaled model but is a reasonable representation of the full sized engine. All the major components are
represented but some are for display
purposes only.
The engine will work with live steam or compressed air at about 5psi and can also be made to operate by means of an electric motor (not provided) for
display purposes
The limitations are as follows:
There is no steam plant included. It is hoped that one will be available in the future, but for now if you wish to operate the engine with live steam, you
will need to provide your own source of steam.
The design of the valve operating gear is different from that described by Farey:. Watt's original engine used drop valves the model uses rotating valves
because of scale limitations and ease of construction.
Again because of scale and practical constructional and operational considerations, the condenser, pumps and governor are for display purposes only
To construct the model, it will be necessary to make small brass components from materials supplied. This involves sawing, drilling and fettling.
The kit is designed so that it can be constructed without the use of a lathe or milling machine but a small bench top or pillar drill would be very useful
as there are some small components which need accurate drilling. Other tools required are
hammer, vice, metric or imperial drill bits, small files, junior hack saw, small screw drivers, small pliers and cutters. Other materials required are matt
black paint, emery cloth, Wood glue and dye/varnish, metal to metal super glue and
gasket sealant
Although the model is not particularly difficult to build, a model making novice may find the construction and setting to work a little too difficult. This
applies especially the valve gear which is quite intricate both in construction and setting up.