Machinery Repairman

(round side), up to the cutting edge. Table 9-4 provides
information on chip clearance for various sized cutters.
Grinding Three- and Four-Sided Cutters
Three- and four-sided cutters (see fig. 9-27) are
used to cut small steel stamps and to engrave small
engraving where a very smooth finish is desired. The
index plate on the toolhead collet spindle has numbered
index holes for indexing to grind three- and four-sided
cutters, as explained in the next paragraph.
Set the toolhead for the desired angle. Plug the pin
in the index hole for the desired number of divisions and
grind the flats. Now, without loosening the cutter in the
toolhead collet, reset the toolhead to the proper
clearance angle. Clearance angles are listed in table 9-5.
PANTOGRAPH ATTACHMENTS
Some attachments commonly used with the
pantograph are copy dial holders, indexing attachments,
Figure 9-27.—Three-sided cutter.
Table 9-4.—Chip Clearance Table for Square-Nose Cutters
Table 9-5.—Clearance Angles for Three- and Four-Sided Cutters
9-20
forming guides, and rotary tables. These attachments
extend the capabilities of the pantograph from flat,
straight line engraving to include circular work,
cylindrical work, and indexing.
When you use a circular copy plate, you may use
the copy dial holder, shown in figure 9-28, instead of
the regular copyholder. This holder has a spring-loaded
indexing pawl, which is aligned with the center pivot
hole. This pawl engages in the notches in a circular copy
plate to hold the plate in the position required to engrave
the character.
You may use an indexing attachment, such as that
shown in figure 9-29, to hold cylindrical work to be
graduated. In some cases, the dividing head (used on the
milling machine) is used for this purpose. The work to
Figure 9-28.—Copy dial holder and plate.