PRIN. OF DRAFTING AND SHOP DRAWINGS - OD1641 - LESSON 1/TASK 4
Reaming is a machine operation that smoothes out the surface of a
From a drawing standpoint, reamings are drawn the same way that
drilled holes are drawn.
The call out notes, however, are different as shown in
figure 87, view B (on the previous page).
c. Counterboring. Counterboring is a machine operation in which part of a drilled
hole is redrilled to a larger diameter (figure 87, view C).
d. Countersinking. Countersinking is a machine operation in which a drilled hole
is redrilled to produce the tapered shape shown in figure 87, view D. Countersinks
are usually made at 82,, but they may be drawn at 90, (45, on each side).