** Measure [310]

Never guess the length of a piece of work—­measure it.

** Home-Made Water Motor [311]

The small water motor shown in the illustration is constructed in the same manner as a German toy steam turbine.  The wheel, which is made of aluminum 1/16 in. thick and 7 in. in diameter, has 24 blades attached to it.

The lugs or extensions carrying the rim must be made from the metal of the wheel, therefore a circle 8 in. in diameter must be first described on the aluminum plate, then another circle 7 in. in diameter within the first and then a circle for the base of the blades, 3-1/2 in. in diameter.  Twenty-four radial lines at equal distances apart are drawn between the two smaller circles and a 1/4-in. hole drilled at the intersecting points of the radial lines and the innermost circle.

Centrally between each pair of radial lines and between the two outer circles, 1/2 by 3/8-in. lugs are marked out and the metal cut away as shown in Fig. 1.  A 1/8-in. hole is then drilled in the center of each lug.  Each division is separated by cutting down each radial line to the 1/4-in. hole with a hacksaw.  Each arm is then given a quarter turn, as shown by the dotted lines in Fig. 2, and the lug bent over at right angles to receive the rim.  The rim is made of the same material as the disk and contains twenty-four 1/8 in. holes corresponding to those in the lugs to receive brass bolts 1/4-in. long.

The disks PP were taken from the ends of a discarded typewriter platen, but if these cannot be readily obtained, they can be turned from metal or a heavy flat disk used instead.

The casing was made from two aluminum cake pans whose diameter was 8 in. at the base, increasing to 9 in. at the rim.  The centers of these were located and a 1/4-in. hole drilled for the

[Illustration:  Fig. 3]

shaft.  The disks P are the same as used on the wheel.  Six holes 1/8-in. in diameter were drilled through the flat part of the rims while the two halves were held together in a vise.  Bolts were placed through these holes to join the casing when ready for assembling.  One side of the casing was then bolted to two 4-in. ordinary metal shelf brackets which were

[Illustration:  Details of Motor]

screwed to a substantial wood base.  This kept one-half of the casing independent of the main structure so that the wheel is easily accessible.

The nozzle was made of 1/2-in. brass pipe which was first filled with molten babbitt metal.  When the metal was cool, a 1/4-in. hole was drilled halfway through the length of the tube, the hole being continued through to the other end by means of a 1/8-in. drill.  The lower orifice was then slightly enlarged with a small taper reamer, and the upper portion of the bore was reamed out almost to the brass to make a smooth entrance for the water.