MILLING MACHINE OPERATIONS - OD1644 - LESSON 1/TASK 1
This tapping should be continued until the parallels cannot be moved by
After once set, additional tightening has a tendency to raise the
work off the parallels.
If the workpiece is so thin that it is impossible to let it extend
over the top of the vise, holddown straps, such as those illustrated in
figure 9 on page 22, are generally used. These straps are hardened pieces
of steel, having one vertical side tapered to form an angle of about 92
degrees with the bottom side and the other vertical side tapered to a narrow
edge. By means of these tapered surfaces, the workpiece is forced downward
onto the parallels, holding them firmly and leaving the top surface of the
workpiece fully exposed to the milling cutter.
Whenever possible, the workpiece should be clamped in the center of
the vise Jaws (see figure 8 on the following page); however, when necessary
to mill a short workpiece which must be held at the end of the vise, a
spacing block of the same thickness as the piece (see figure 8) should be
placed at the opposite ends of the jaws.
This will avoid strain on the
movable jaw and prevent the piece from slipping.