pair of inside calipers which are bent so as to be well adapted for calipering distances difficult of access, such as the keyway in a shaft and hub which does not extend beyond the hub, as indicated. With the ordinary inside calipers, having straight legs, and which are commonly used for inside work, it is generally impossible to get the exact size, as the end which is held in the hand comes in contact with the shaft before both points come into the same vertical plane. The engraving plainly shows how calipers for this purpose are made, and how used. Any mechanic can easily bend a common pair to about the shape shown to accommodate this class of work.^[3]

Fig. 8. Inside Calipers for Close Spaces

Surface Gage with Two Pointers

Figs. 9 and 10 show a special surface gage, and illustrate an original idea which has been found to be a great saver of time and of milling cutters. It can also be used on the planer or shaper. By its use the operator can raise the milling machine table to the right height without testing the cut two or three times, and eliminate the danger of taking a cut that is liable to break the cutter. This tool is especially valuable on castings, as raising the table and allowing the cutter to revolve in the gritty surface while finding the lowest spot is very disastrous to the cutting edges.

Figs. 9 and 10. Surface Gage with Two Pointers

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

Fig. 11. Method of Adjusting the Needle of a Surface Gage

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

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.

Fig. 14. Method of Setting Dividers Accurately

Combination Caliper and Divider

The combination caliper and divider shown in Fig. 15 is one that is not manufactured by any of the various tool companies. It is, however, one of the handiest tools that can be in a machinist's kit, as it lends itself to so many varied uses, and often is capable of being used where only a special tool can be employed. The illustration suggests its usefulness. The tool can be used as an outside caliper, as an inside caliper, and as a divider. The common form of this tool has generally only one toe on the caliper legs, but the double toes save the reversal of the points when changing from outside to inside work. The divider points may be set at an angle, which permits of stepping off readily around the outside of a shaft at angular distances, where the ordinary dividers are useless. A number of other uses could be mentioned, but any intelligent mechanic can readily