TM 9-4910-638-14&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 he desired finished size. Two thousandths is
the proper amount for finish cut. After setting the micrometer, lock it with the micrometer lockscrew. Loosen the plunger
lockscrew and place the R tool holder along the micrometer spindle as shown in figure 9. Move the plunger until the length
of the tool, tip of tool to tip of plunger, is approximately 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 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 and tool bit out against the face of the micrometer body with a light spring
pressure
- 14 -
