To use this surface gage, the pointer marked _C_ in Fig. 9 is set to the lowest spot in the casting, and then the pointer _B_ is set from it with perhaps 1/32 inch between the points for a cut sufficient to clean up the surface. Pointer _C_ is then folded up as shown at _C'_ in Fig. 10, and the table is raised until the pointer _B_ will just touch the under side of the cutter as shown at _B'_ in Fig. 10. In this way the table is quickly adjusted to a cut that will clean the casting or other piece being machined, and with no cutting or trying whatever.[4] To Adjust the Needle of a Surface Gage [Illustration: Fig. 11. Method of Adjusting the Needle of a Surface Gage] [Illustration: Fig. 12. Scale Attachment for the Square] Fig. 11 illustrates a method of adjusting the needle of a surface gage. To set the gage 3¾ inches from the table, get somewhere within ¼ inch of the mark on the square. With the thumb and forefinger on hook _A_, turn the needle till it reaches the point desired. By turning the needle, it will travel in a circular path, on account of the bend near the point, and thus reach the desired setting. Scale Attachment for the Square Fig. 12 shows a device for attaching a scale to a square. This combination makes a very convenient tool to use when setting up work for keyseating, as is illustrated in the engraving, in which _S_ is the shaft to be splined and _C_ the milling cutter. It is also a very handy tool for truing up work on the boring mill or lathe. At the upper left-hand corner, is shown the construction of the parts, which are made of dimensions to suit the size of the scale and the square. For the combination to be successful, it is essential that the blade of the square is the same thickness as the scale.[5] Attachment for Machinist's Scale [Illustration: Fig. 13. Convenient Attachment for Machinist's Scale] Fig. 13 shows a very convenient appliance. It will be found very useful in the machine shop for setting inside calipers to any desired size. The gage is clamped over the rule wherever desired, and one leg of the calipers set against the gage, the other leg being brought flush with the end of the scale.[6] Setting Dividers Accurately To set dividers accurately, take a 1-inch micrometer and cut a line entirely around the thimble as at _A_, Fig. 14, and then, with the instrument set at zero, make a punch mark _B_ exactly one inch from the line on the thimble. If less than one inch is wanted, open out the micrometer and set the dividers to the dot and line so as to give one inch more than the distance wanted. Now with the dividers make two marks across a line, as at _a_ and _b_, Fig. 14, and then set the dividers to one inch and mark another line as at c. The distance from _c_ to _b_ is the amount desired, and the dividers can be set to it. Great care must, of course, be exercised, if accurate results are required. [Illustration: Fig. 14. Method of Setting Dividers Accurately] Combination Caliper and Divider