Delta 70-200 - Manual (Page 14)

14
DRILLING METAL
Use clamps to hold the work when drilling in metal. The work should never be held in the bare hand;
the lips of the drill may seize the work at any time, especially when breaking through the stock. If the
workpiece is whirled out of the operator’s hand, he may be injured. In any case, the drill will be broken
when the work strikes the column.
The work must be clamped firmly while drilling; any tilting, twisting or shifting results not only in a rough
hole, but also increases drill breakage. For flat work, lay the piece on a wooden base and clamp it
firmly down against the table to prevent it from turning. If the piece is of irregular shape and cannot be
laid flat on the table, it should be securely blocked and clamped.
BORING IN WOOD
Twist drills, although intended for metal drilling, may also be used for boring holes in wood. However,
machine spur bits are generally preferred for working in wood; they cut a square bottom hole and are
designed for removal of wood chips. Do not use hand bits which have a screw tip; at drill press speeds
they turn into the wood so rapidly as to lift the work off the table and whirl it.
For through boring, line up the table so that the bit will enter the center hole to avoid damage. Scribe
a vertical line on the front of the column and a matchmark on the table bracket, so that the table can
be clamped in the center position at any height.
Feed slowly when the bit is about to cut through the wood to prevent splintering the bottom face. Use
a scrap piece of wood for a base block under the work. This helps to reduce splintering and protects
the point of the bit.