Page:Popular Mechanics 1928 01.pdf/174

 placed the materials used for making the lift on one end of a plank, pivoted in the center, to balance the counterweight on the other end. When both weights were equal, I added about 8 lb. to the counterweight. Then I proceeded to build the lift, which was made with double sides, top and bottom in order to make it solid and heavy. Ordinary 1 by 6-in. lumber was used. Angle iron may be used to add weight and rigidity but it must be rememhered that no additional material must be used besides that which was balanced with the counterweight. Between the two boards forming the side, a groove is left for the guide, on each side. The pulley assembly is then made. It must be carefully calculated where the ropes and weights are to hang in order to be sure that they clear the lift while in motion or at rest, and the weight must be hung in a position where it can do no damage if it falls. The pulleys need be of no special size; anything from 2 to 7 or 8 in. will do. They must, however, be of the grooved type and able to retain a $3/8$-in. rope. Lengths of pipe or rod make good axles. I used one 2-in. and two 4-in. pulleys, the rope passing over the large ones and under the small one to provide the necessary friction to hold the waiter steady at the top or bottom, yet allow it to move freely when pulled up or let down. Ordinary sash cord is well suited for use in a dumb-waiter.



 

Coiling wire for springs, electrical coils or for binding purposes, is accomplished usually with some means to restrain the wire and keep it under tension. Leather and wood will serve for holding the wire under tension while it is fed on a lathe mandrel at a slow speed. A new means, differing from any of the customary practices, is shown in the attached drawing, and consists of a short length of small copper pipe, with abrupt bends, which restrains the wire and maintains sufficient friction to insure tightly wound coils, in spite of the fact that the operation is rapid and the wire tension uniform.



