TM 9-4910-579-14&P
SETTING THE TOOL IN THE BORING HEAD
Determine the size to bore and set the micrometer. Each graduation of the micrometer body, or one revolution of the
thimble, represents fifty thousandths.
For the roughing cut, the micrometer should be set two thousandths smaller than the desired finished size. Two
thousandths is the proper amount for the finish cut. After setting the micrometer, lock it with the micrometer lockscrew.
Loosen the plunger lockscrew and place the R tool holder along side the micrometer spindle as shown in Figure 9. Move
the plunger until the overall length of the tool, tip of tool to tip of plunger, is approximately 1/2 inch longer than the
extended length of the micrometer stem.
FIGURE 9
SETTING THE TOOL IN THE BORING HEAD
CAUTION
UNLESS THE PLUNGER IS PROPERLY SET, IT WILL BE IMPOSSIBLE TO MAINTAIN
UNIFORMITY OF BORE SIZES.
Figure 9 shows the tool holder in the boring head ready to be locked in position. The small spring plunger is partly
compressed, thus pushing the tool holder .ad tool bit out against the face of the micrometer body with a light spring
pressure.
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