Bore a 1/4-in. hole through the center of the
blocks in the 2 in. direction. Remove the clamp and set the nut
into one of the blocks, so that the hole will be continuous with
the hole in the wood. Cut out a piece from the block combination,
leaving it shaped like a bench, and glue the bottoms of the legs
to a piece of thin board about 2-1/2 in. square for a support.
Solder one end of a stiff wire that is about 2 in. long to the
head of the bolt at right angles to the shaft, and fix a disc of
heavy pasteboard with a radius equal to the length of the wire,
and with its circumference graduated into equal spaces, to serve
in measuring revolutions of the end of the wire, to the top of the
bench. Put the bolt in the hole, screwing it through the nut,
[Illustration: Micrometer]
and the construction is complete. The base is improved for the
measuring work by fastening a small piece of wood on the board
between the legs of the bench. A small piece of metal is glued on
this piece of wood at the point where the bolt meets it.
Find the number of threads of the screw to the inch by placing the
bolt on a measuring rule, and counting the threads in an inch of
its length.
Pages:
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323