Fig. 29 shows a very simple and light five-inch micrometer that can be quickly set to exact position from one to five inches. The round beam is graduated by a series of angular grooves, 1 inch apart, which are of such a form and depth that the clamping fingers at the end of part _A_ spring in, allowing one inch adjustment of the beam to be quickly and positively made. The sleeve _K_ is of tool steel, being counterbored from the forward end for all but one-half inch of its length. For this half inch it is threaded on the inside and acts as a micrometer nut. The outside of the same end is threaded to receive the adjusting nut _F_, and two slots are cut in the sleeve, at 90 degrees with the graduations. These slots, by a movement of the nut _F_, provide a means for compensating for wear. The bushing _E_ is hardened and lapped, and fitted tightly in the forward counterbore of this sleeve, where it acts as a guide for the front end of the micrometer screw. The barrel _J_ is the same as that of a regular micrometer, and is graduated in 0.025 inch divisions. The most essential part of the tool is the threaded screw _I_, over the end of which fits the barrel _J_. The end is tapped out to receive the speeder _H_, which serves to hold the barrel in position. The thread is 5/16 inch in diameter, with 40 threads per inch, while the unthreaded part is hardened, ground and lapped. To adjust the instrument, loosen the speeder _H_ and turn the barrel until the proper adjustment is obtained; lock the barrel by again tightening the speeder. The beam _C_ has a ¼-inch hole drilled throughout its entire length in order to make it light. Small 90-degree grooves are cut into it at intervals of 1 inch, and a 1/8-inch slot is milled through one side to within 1¼ inch of the forward end. The back end of part _A_ forms a spring-tempered split chuck, which grips the beam and holds _A_ in position, while the exterior is threaded to receive the knurled cap _B_ by which the chuck is tightened firmly to the beam. From the front end, toward the split chuck, the body is counterbored 5/8 inch and the bushing _D_ driven in tight. This bushing has a key _G_ fitted into it, which slides in the slot of the beam and prevents the arm from turning. The projecting arm is bored and tapped to receive the sleeve _K_. This gage must be carefully and accurately made to be of value.[16] Inside Micrometer for Setting Calipers [Illustration: Fig. 30. Method of Setting Calipers from Inside Micrometers] Fig. 30 shows an application of inside micrometers which is very handy. The hole for the scriber in the scriber clamp of a surface gage is reamed out to fit the rods used with inside micrometers. This forms a convenient holder for the micrometer when used for setting outside calipers to it. The calipers can be set easily and accurately at the same time, and where extreme accuracy is not necessary this arrangement is more handy than that of using large-sized micrometers.