# Page:Popular Science Monthly Volume 89.djvu/485

Popular Science Monihli/

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IN the shop it is often necessary for the workman to read dimensions from blueprints that are half size, three- quarter size, etc. The usual practice is to caliper the dimension, transfer it to a ruler, and multiply it in order to get the actual size. It is a very simple matter to fix up \-our calipers so that they will be

���Method of Improving Calipers So as to Eliminate Involved Calculations

ready directl\-, thus giving the full size without any calculation.

Measure accurately the distance A, B, and divide it into four equal parts. In the same way lay oft points on .-1 C. These points should be in a straight line, from A to C, and from A to B. Holes should then be drilled at these points and tapped to take small long machine screws. Be careful to drill the holes perfectly straight and perpendicu- lar.

Now put the machine screws in the holes. If >2 scale is to be read, place them in No. 2 and No. 5; then the distance between the ends of the dividers is just twice that between the machine screws. To read ^4, use holes Nos. 3 and 6. Nos. i and 4 give 3-4 size.

The time spent in making this im- provement will be more than saved in actual use. — R. L. Kenvon.

Soldering Iron for Light Work

A SOLDERING copper f(jr light work can be made from a length of trolley wire one end of which is filed to a point and the other end bent to fit into a wooden handle.

��The Completed Iron, Showing Simplicity and Neatness of Its Construction

��Making a Driving-Box Lifter

THL device wiiich is illustrated here- with is designed to be used for lifting dri\-ing-l)oxes with a traveling crane, for use with planers, boring-mills, drill-presses and the like. It is made from two forgings and a ^'s-in. chain. The two rectangular links are made from

'4-in. iron. The ring is made first, then

the rectangle, and lastly the two are welded. The link slips over the driving box and the ring is used in the crane hook.

Just as soon as the crane hook is hoisted, the two links are drawn to- gether. An accident is practically im- pos-sible. The size of the link can be made to fit any driving-box, though it can be used for any box it will go over, unless the box happens to be very much too small. — Joseph K. Long.

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