Operation; Operating Precautions; Drilling Recommendations - Jet JDP-20EVS-110 Operating Instructions And Parts Manual

9.0 Operation

9.1 Operating precautions

The following operating and safety precautions
must be observed in order to avoid harm to
operator or damage to drill press.
1. Head assembly must be locked to column so
the thrust produced by drilling will not force the
head assembly up the column.
2. Work table must be locked to column so it will
not be forced down the column.
3. Be sure belt is tightened to proper tension.
4. Do NOT start to drill workpiece until making
certain workpiece is held down securely.
5. MAKE SURE DRIVE MOTOR IS RUNNING
BEFORE turning speed shift lever (I, Figure 7-
1) in either direction.
6. Point of operation protection is required for
maximum safety.
responsibility of the user/purchaser since
conditions differ between jobs.
7. Make sure the drill is secured in the spindle or
chuck before attempting to use the drill press.
8. Make sure spindle taper is clean and free of
burrs, scoring, and galling to assure maximum
gripping.

9.2 Drilling recommendations

9.2.1 Drilling speeds
The speed of a drill is usually measured in terms of
the rate at which the outer periphery of the tool
moves in relation to the work being drilled. The
common term for this is Surface Feet per Minute
(SFM). The relationship of SFM is expressed in the
following formulas:
SFM = 0.26 X rpm X Drill Diameter (in inches)
RPM = 3.8 x ________SFM__________
Drill diameter (in inches)
In general, the higher the speed the shorter the drill
life. Operating at the low end of the speed range
for a particular material will result in longer life. The
most efficient speed for drill operation depends
upon many variables:
1. Composition and hardness of material.
2. Depth of hole.
3. Efficiency of cutting fluid.
4. Type and condition of drilling machine.
5. Desired quality of hole.
6. Difficulty of set-up.
This remains the
9.2.2 Drilling feed
The feed of a drill is governed by size of tool and
the material drilled. Because feed rate partially
determines rate of production and also is a factor in
tool life, it should be chosen carefully for each job.
In general, the most effective feeds will be found in
the following ranges:
Diameter of Drill
(inches)
Under 1/8
1/8 to 1/4
1/4 to 1/2
1/2 to 5/8
9.2.3 Excessive speed/feed indicators
A drill that splits up the web is evidence of too
much feed or insufficient tip clearance at the center
as a result of improper grinding. The rapid wearing
away of the extreme outer corners of cutting edges
indicates that speed is too high. A drill chipping or
breaking out at the cutting edges indicates that
either feed is too heavy or drill has been ground
with too much tip clearance.
9.2.4 Speeds for high speed steel drills
Material
Alloy Steel — 300 to 400 Brinell
Stainless Steel
Automotive Steel Forgings
Tool Steel, 1.2C
Steel, .4C to .5C
Mild Machinery Steel, .2C to .3C
Hard Chilled Cast Iron
Medium Hard Cast Iron
Soft Cast Iron
Malleable Iron
High Nickel Steel or Monel
High Tensile Bronze
Ordinary Brass and Bronze
Aluminum and its Alloys
Magnesium and its Alloys
Slate, Marble, and Stone
Plastics and similar materials (Bakelite)
Wood
Titanium Alloys
Titanium Alloy Sheet
Note: In cases where carbon steel drills are applicable, the
drill should be run at speeds of 40 to 50 percent of those
given above.
12
Feed per Revolution
(inches)
0.001 to 0.002
0.002 to 0.004
0.004 to 0.007
0.007 to 0.015
Table 2
Speed
(SFPM)
20-30
30-40
40-50
50-60
70-80
80-110
30-40
70-100
100-150
80-90
40-50
70-150
200-300
200-300
250-400
15-25
100-150
300-400
10-25
50–60
Table 3