Delta ShopMaster 638517-00 - Manual (Page 15)

15
T R O U B L E S H O O T I N G
CORRECT DRILLING SPEEDS
Factors which determine the best speed to use are: kind of material being worked, size of hole, type of drill or other
cutter, and quality of cut desired.
Use the recommended speed for the drill press bit and workpiece material.
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 flat 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 to the table. Scribe a vertical
line on the front of the column and a matching mark on the table bracket and the drill press head, so that the table and
drill press head 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 as a base block under the work; this helps to reduce splintering and protects the point of the bit.
DRILLING METAL
Use clamps to hold the work when drilling metal. The work should never be held in the bare hand; the drill bit may seize
the work at any time, especially when breaking through the stock. If the piece is whirled out of the operator's hand, the
operator may be injured. The drill bit will be broken if 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 bit 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.