The great bugbear staring the amateur mechanic in the face when he
contemplates making a small steam engine is the matter of boring the
cylinder. To bore an iron cylinder on a foot lathe is difficult even
when the lathe is provided with automatic feed gear, and it is almost
impossible with the ordinary light lathe possessed by most amateurs. To
bore a brass cylinder is easier, but even this is difficult, and the
cylinder, when done, is unsatisfactory on account of the difficulty of
adapting a durable piston to it.
The engravings show a simple steam engine, which requires no difficult
lathe work; in fact the whole of the work may be done on a very ordinary
foot lathe. The engine is necessarily single-acting, but it is effective
nevertheless, being about 1-20 H. P., with suitable steam supply. It is
of sufficient size to run a foot lathe, scroll saw, or two or three
sewing machines.
The cylinder and piston are made from mandrel drawn brass tubing, which
may be purchased in any desired quantity in New York city. The fittings
are mostly of brass, that being an easy metal to work.
The principal dimensions of the engine are as follows:
Cylinder.--Internal diameter, 1½ in.; thickness, 1/8 in.;
length, 3-3/8 in.
Piston.--External diameter, 1½ in.; thickness, 3-32 in.; length,
3¾ in.
Length of stroke. 2 in.
Crank pin.--Diameter, 1/4 in.; length of bearing surface, 1/2 in.
Connecting rod.--Diameter, 5/16 in.; length between centers, 5½
in.
Shaft.--Diameter, 5/8 in.; diameter of bearings, 1/2 in.; length. 6
in.; distance from bed to center of shaft, 1½ in.
Flywheel.--Diameter, 8 in.; weight, 10 lb.
Valve.--Diameter of chamber, 9-16 in.; length, 1¼ in.; width of
valve face working over supply port, 3/32 in.; width of space under
valve, 3/8 in.; length of the same, 1 in.; distance from center of
valve spindle to center of eccentric rod pin, 3/4 in.
Ports, supply--Width, 1/16 inch.; length, 1 in. Exhaust.--Width,
1/8 in.; length, 1 in.; space between ports, 5-16 in.
Pipes.--Steam supply, 1/4 in.; exhaust, 3/8 in.
Eccentric.--Stroke, 3/4 in.; diameter, 1-5/16 in. length of
eccentric rod between centers, 8-3/8 in.