Delta 11-950 Instruction Manual download pdf (Page 13)

CORRECT DRILLING SPEEDS

Factors which determine the best speed to use in any drill press operations are: material, size of hole, type of drill or

other cutter, and quality of cut desired. The smaller the drill, the greater the RPM required. When drilling in soft

materials, use a higher speed than what would be used for harder materials.

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 piece is whirled out of the operators

hand, he may be injured. 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 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. 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.

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Delta 11-950 Instruction Manual Page 13