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.
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.
Wooden base, 6¼ in x 8 in.: 2-3/8 in. thick.
Thickness of plate supporting cylinder, 3/8 in.
Distance from base plate to under side of cylinder head. 9¼ in.