This section is from the book "The Boy Mechanic Vol. 2 1000 Things for Boys to Do", by Popular Mechanics Co.. Also available from Amazon: The Boy Mechanic, Vol2: 1000 Things for Boys to Do.
Wherever a water pressure of over 30 lb. is available a small hydroelectric-power plant will produce sufficient electric current for any light work, such as charging storage batteries, operating sewing and washing machines, toys, etc. The design is for a 6-in. hydraulic motor of the Pelton type, which will operate well on almost all city-water pressures, and at
80 lb. will drive a 100-watt generator to its full output.
The castings may be procured from any foundry cheaply, so that these parts need not trouble the builder. The patterns can be constructed easily and are not so complicated that they will tear the molds when being removed. They are made from well seasoned white pine, 1/4 in. thick. Fill in all sharp corners with small fillets. All the patterns should taper slightly from the parting line.
The motor casing is shown in Fig. 1, It is made with a wide flange so that the cover plate can be bolted to it. The lug A is to give additional strength and thickness to the side so that it may be drilled and tapped for the nozzle. The legs B and C are for bolting the case to a base or support. The outlet pipe is of lead, 1 3/4 in. outside diameter, and the hole for it in the case can be either drilled or cored. Solder the pipe flush with the inside of the casing. Drill and tap the holes around the flange for 8, 32 bolts. The shaft hole must be drilled very carefully. Drill 1/4 -in.holes in the feet. The oil holes are 1/8 in. in diameter. File the surface of the flange smooth and also the inside shoulder of the bearing lug. Drill and tap the nozzle hole for a 3/4-in. pipe thread.
The cover plate is shown in Fig. 2. This is bolted to the casing with 8, 32 brass bolts, 1/2 in. long. The holes for them are drilled 3/16 in. in diameter. A shallow hole, for the end of the shaft to fit in, is drilled in the lug, as shown.
Ill: The Best Shape of the Buckets to Take Up the Force of the Water
It does not pass all the way through the plate. File the inside face of the lug smooth and also the edge of the plate where it joins the casing.
The wheel, with brackets attached, is shown in Fig. 3. This style of wheel need not be followed out closely. Bore the hub centrally for a 1/4-in.
shaft and fit in two setscrews. Drill and tap the rim for the buckets with a 1/4-in. standard tap. The buckets must be evenly spaced and bolted on to make the wheel balance.
Ill: The Motor as It is Coupled to Drive the Dynamo, and the Water Connections
The buckets are shown in Fig. 4. They may be cast from iron or babbitt. The sharp ridge in the center provides for a deviation of the water jet as it flows on the bucket. The ridge divides the bucket into two equal lobes which turn each division of the jet through almost 180 deg., using all the kinetic energy in the jet. This is shown at D. The dividing ridge must lie in the plane of the revolution, so that each bucket will enter the center of the jet. The buckets being evenly spaced on the periphery of the wheel, only one at a time receives the force of the jet, the one in front and the one behind clearing the jet.
The nozzle is shown in Fig. 5. It can be made of iron or brass. The inside gradually tapers from 3/4 to 3/16in. It has a 3/4-in. pipe thread and is screwed into the hole in the case from the inside and is secured with a lock nut. Enough additional threaded portion is left protruding to allow the supply pipe to be connected.
When assembling the motor, fasten the wheel to the shaft with the two setscrews, and place a metal washer, E, on each side of the wheel. Place the wheel in the casing and screw the cover plate in place. A thin rubber gasket should be placed between the cover and the casing to provide a water-tight joint.
The general arrangement of the plant is shown in Fig. 6. The motor and dynamo are mounted on a heavy wood base, which in turn is firmly bolted to a concrete foundation. Level up the two machines by the use of thin washers on the bolts between the base and machine. A heavy sleeve and set-screws are used to connect the two shafts. The connection to the water supply is made with 3/4-in. pipe, with a globe valve in it to regulate the flow of water. Any dynamo of about 100-watt output can be used.