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graduations backwards; then no difficulty will be experienced in using it as an inside micrometer.

In all shops where micrometers are used generally it will faciliate their use and expedite the production of accurate work by having the feed-screws of all machines fitted with graduated dials; and if the micrometers in use are graduated to read in thousandths, by having the dials to read the same.

The universal use of micrometer-calipers for regular machineshop gauges is not far distant, as it will not be long before the chief and perhaps the only interdiction to their extensive usetheir cost-will be overcome. That the demand is growing is evidenced by the fact that one concern in the East manufactures a line measuring from six to twelve inches for use on the larger classes of interchangeable machine work.

THE HEIGHT-GAUGE AND ITS USE.

While the micrometer occupies first place among the small precision tools of the universal shop, there is another tool which follows it a close second. I refer to the height-gauge, Fig. 301; a tool that although it is used quite generally among tool-makers, is comparatively unknown outside of them. If more were known of the great utility of this handy, accurate, reliable, and almost indispensable tool, its use would become common in all shops where accurate work is done. By many the height-gauge is thought to be merely an accessary to the tool-maker's kit, and of no use except in verifying measurements; when, on the contrary, it can be used for a thousand and one jobs in the attainment of results with ease which would otherwise be almost impossible of attainment were other means used. In accurate work, especially, by means of the height-gauge, jobs that appear to present insurmountable difficulties are accomplished with ease.

In order that the utility and value of this accurate tool may become better understood I will present a few examples of its use:

By far the most usual and common method of striking or scribing a line on a piece of work is with the surface-gauge; setting the scriber to some graduation on a scale. This method, however, is not to be compared with the height-gauge and its

scriber in point of economy of time, labor, and worry; for the reason that the height-gauge may be set almost instantly and accurately when one is familiar with it, and a line may be scribed with it at once with the assurance positive that it is in exactly the place that one wishes it to be. With the surface-gauge the scriber must be raised and lowered many times before the correct (?) height is obtained; even then the final setting is a guess.

7

1

FIG. 301.

For example second, let us say that it is necessary to locate eight holes in a circular finished casting as per Fig. 303; the holes to form the corners of two squares, one within the other, with the four holes of each equidistant from the centre of the casting. The way to accomplish the desired results accurately with ease will be to take an angle-plate like 302, true it on three of its sides, and then clamp the disk on its face A. The exact diameter of the casting in which the holes are to be located is found first; then the height of its lower edge from the surfaceplate on which the angle-plate rests; then, by means of the

veriner on the height-gauge and the scriber which comes with it, we scribe two lines the required distance apart, equally above

Bolt Holes

FIG. 302.

and below the centre, for the outside square, then two more lines for the inside square. Next, without removing the casting from

Centers

Centers

FIG. 303.

Centers

Centers

the angle-plate, we turn the plate on to face B and then scribe four lines in a like manner, thus finishing the two squares.

All

is now ready to drill and tap the eight holes approximately correct, where the lines intersect, for the "button" screws, which we use to locate the "buttons" true for boring the holes. From this example it will be at once obvious that holes may be located in a like manner on any given surface, providing that care has been previously taken to have the surfaces from which the necessary measurements are taken perfectly true and square with each other.

For the third example, we will take the block shown in Fig. 304, which has a hole at Cand in which it is desired to drill two more holes centrally with the first one way, but at angles with it the other, as shown by the dotted lines. We first bolt the angle-plate on the table of the miller, square with the spindle,

Angular Holes

C

FIG. 304.

and then fasten the block to the angle-plate, at the required angle with the table. We locate a plug in the hole first drilled at C, as shown in Fig. 305, and then find with the height-gauge the exact distance the centre of the hole is from the table. Then, with a plug in the miller-spindle-which must run perfectly true -we measure from the plug to the table, raise or lower the knee until the centre of the spindle is the same distance from the table that the centre of the plug in hole C is, setting it horizontally, by measuring from the plug in the spindle to the angleplate, or the edge of the block to be drilled, with the heightgauge. We have now everything ready to bore one of the angu lar holes; which may be accomplished by using a draw-in collet end-mill, or a single-pointed boring-tool, to finish the hole. The other hole may then be finished in the same manner by reversing the block on the angle-plate and proceeding as before.

In conclusion I may state that experience has proved that more accurate and expeditious results can be obtained with the height-gauge than the surface-gauge. Lay out your work with the height-gauge; prickpunch carefully where the lines intersect

Strap Bolt

Angle Plate

Stud

Angular Hole

Strap Bolt

Block

Miller Platen

FIG. 305.

-using a glass where unusual accuracy is essential-and indicate carefully on the lathe face-plate; drill the hole, and finish it by boring. In this manner you will get as near perfect accuracy as it is possible to get.

If you are machinist, tool-maker, or die-maker, learn of the multiple uses of the micrometer-caliper and the height-gauge; and your ability to do fine and accurate work will be further developed and your earning capacity will be increased. If you are a shop manager, superintendent, or foreman, furnish your de partments and tool-rooms with such tools and teach your men how to use them; as by so doing your shop will produce more and better work accurately with ease.

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