TM 9-243TYPES AND USESSURFACE GAGEA surface gage is a measuring tool used to transfermeasurements to work by scribing a line, and to indicatethe accuracy or parallelism of surfaces. The surfacegage consists of a base with an adjustable spindle (1) towhich may be clamped a scriber or an indicator (2).Surface gages are made in several sizes and are clas-sified by the length of the spindle. The smallest spindleis 4 inches long, the average 9 to 12 inches, and thelargest 18 inches. The scriber is fastened to the spindlewith a clamp. The bottom and the front end of the base ofthe surface gage have deep V-grooves. The groovesallow the gage to measure from a cylindrical surface.The base has two gage pins (3). They are used againstthe edge of a surface plate or slot to prevent movementor slippage.RULE DEPTH GAGEmarks (1) located on the sliding head (2). The rule depthgage is a graduated rule (3) with a sliding head (2)designed to bridge a hole or slot. The gage holds the ruleat a right angle to the surface when taking measure-ments. This type has a measuring range of 0 to 5 inches.The sliding head has a clamping screw so that it may beclamped in any position. The sliding head is flat andperpendicular to the axis of the rule. It ranges in sizefrom 2 to 2-5/8 inches wide and from 1/8 to 1/4 inch thick.MICROMETER DEPTH GAGEThe micrometer depth gage consists of a flat base (1)that is attached to the barrel of a micrometer head (2).These gages have a range from 0 to 9 inches, depend-ing on the length of extension rod used. The hollowmicrometer screw has a 1/2 or 1 inch range. Some areprovided with a ratchet stop. The flat base ranges in sizefrom 2 to 6 inches. Several extension rods are suppliedwith this type gage:NOTEFor additional information on microme-ters, see chapter 7 in this manual.A rule depth gage measures the depth of holes, slots,counterbores, and recesses. Some rule depth gages,such as the one shown above, can also be used tomeasure angles. This is done by using the angle14-2
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