This document provides information on various types of drilling machines and their parts and operations. It describes portable, sensitive, upright, radial, gang, multiple spindle, automatic and deep hole drilling machines. It outlines the main parts of an upright drilling machine including the base, column, table, head, spindle assembly, and drive and feed mechanisms. It also discusses workholding devices, toolholding devices, and common drilling machine operations such as drilling, reaming, boring, counterboring, countersinking, spot facing and tapping.

1. DRILLING
• Drilling machine is the most important in a workshop.
• As regards its importance it is second only to the lathe.
• Primarily designed to originate hole.
• Holes maybe drilled quickly and at a low cost.
• Hole is generated by the rotating edge of a cutting tool known as the drill which
exerts large force on the work clamped on the table.

2. Types of drilling machines
1. Portable drilling machine
2. Sensitive drilling machine
a) bench mounting b) flour mounting
3. Upright drilling machine
a) round column section b) box column section.
4. Radial drilling machine
a) plain b) semiuniversal c) universal
5. Gang drilling machine
6. Multiple spindle drilling machine
7. Automatic drilling machine.
8. Deep hole drilling machine.
a) vertical b) horizontal

3. Portable drilling machine
• Can be operated with ease anywhere in
the workshop.
• Some of the machines operated by hand
power, but most of the machines are
driven by individual motor.
• Entire drilling mechanism including the
motor is compact and small in size.
• Motor is universal type which may be
driven by both A.C and D.C.
• The maximum size of the drill that it can
accommodate is not more than 12 to
18mm.
• Can be operated at high speeds.
• Some of the portable machines are driven
by pneumatic power.

4. Sensitive drilling machine
• Small machine designed for drilling a small holes
at high speed in light jobs.
• Base of the machine may be mounted on a
bench or floor.
• It consists of a vertical column, a horizontal
table, a head supporting the motor, driving
mechanism , and a vertical spindle for driving
and rotating the drill.
• No arrangement for for any automatic feed of
the drill spindle.
• The drill is fed into the work by purely hand
control.
• Hand feed permits the operator to feel or sense
the progress of the drill into the work.
• As the operator senses the cutting action, at any
instant, it is called sensitive drilling machine.
• Capable of rotating drills of diameter from 1.5 to
15.5 mm.
• Super sensitive drilling machines are designed
to drill holes as small as 0.35mm in diameter
and the machine is rotated at high speed of
20000 r.p.m.

5. Upright drilling machine
• Designed for handling medium sized
workpieces.
• Similar to a sensitive drill and is supplied
with power feed arrangement.
• Large number spindle speeds and feeds
may be available.
There are two general classes
1. Round column section or pillar drilling m/c.
2. Box column section
Round column section-
consists of a round column that rises from the
base which restson the floor, an arm and
round table assembly, and a drill head
assembly.
Arm and table may be moved up and down on
the column.
May be moved in an arc upto 180o

6. Upright drilling machine
• heavy and odd-size work may be
supported directly on the base of the m/c
and drilled after the arm is swung out of
the way.
• Table may be rotated 360o about its own
centre.
• Can drill upto 50 mm.
Box column section:
Has the square table fitted on the slides at the
front face of the machine column.
Heavy box column gives the machine strength
and rigidity.
Table is raised or lowered by an elevating
screw that gives the additional support to the
Table.
Holes more than 50mm can be drilled by it.

7. Radial drilling machine
• Intended for drilling medium to large and
heavy work piece.
• m/c consists of a heavy, round, vertical
column mounted on a large base.
• Column supports a radial arm which can
be raised and lowered to accommodate
work pieces of different heights.
• Arm may be swung around to any position
over the work bed.
• Drill head containing mechanism for
rotating and feeding the drill is mounted
on a radial arm and can be moved
horizontally on the guide ways and
clamped at any desired position.
• The work may be mounted on the table or
on the floor.

8. Radial drilling machine
Plain radial drilling m/c
Provisions are made for vertical adjustment of
the arm, horizontal movement of the drill
head along the arm, and circular movement of
the arm in horizontal plane about the vertical
column.
Semi-universal m/c
In addition to the above three movements
drill head can be swung about horizontal axis
perpendicular to the arm.
Fourth movement permits drilling hole at an
angle.
Universal m/c
In addition to the above four movements, arm
holding the drill head may be rotated on a
horizontal axis.

9. Gang drilling machine
• Number of single spindle drilling machine
columns are placed side by side on a
common base and a common work table.
• Four to six spindle mounted side by side.
• Some m/c s spindles are permanently
spaced on the work table, and in others
the position of the columns may be
adjusted.
• Speed and feed controlled independently.
• Specially adopted for production work.
• Series of operations may be performed on
the work by simply shifting work from one
position to other on the work table.
• Each spindle may be set up properly with
different tools for different operations.

10. Multiple spindle drilling machine
• Function of a multiple spindle m/c is to
drill a number of holes in a piece of work
simultaneously and to reproduce the
same pattern in number of identical
pieces.
• Several spindles are driven by a single
motor.
• Feeding motion is obtained by both raising
the table and lowering the drill head.
• Drill jigs may be used in mass production.
• Spindles centre distances can be adjusted.
• Spindles are connected to the main drive
by universal joints.

11. Automatic drilling machine
• It can perform a series of machining
operations at successive units and transfer
the work from one unit to the other
automatically.
• Finished work comes out from the last
m/c without any manual handling.
• It is used for production purposes.

12. Deep hole drilling machines
• Special m/c s and drills are required for
drilling deep holes in rifle barrels, crank
shafts, long shafts etc.,.,
• Machine is operated at high speed and
low feed.
• A long job is usually supported at several
points.
• The work is rotated while the drill is fed
into the work.

13. Size of a drilling machine
• Portable drilling machines is specified by the maximum diameter of the drill that it can hold.
• The sensitive and upright drilling machines are specified by the diameter of the largest piece
that can be centered under the spindle.
• Maximum size of the drill that the m/c can operate.
• Table diameter
• Maximum spindle travel
• Number of spindle speed and feeds available.
• Morse taper of the drill spindle.
• Power input.
• Floor space required.
• Net weight.
• Radial drilling m/c is specified by the diameter of the column and length of the arm . Others
are maximum drilling radius, spindle speeds and feeds etc.,

14. Upright Drilling Machine Parts
• Base
• Column
• Table
• Head
• Spindle, quill and drill head assembly
• Spindle drive and feed mechanism

15. column
• Vertical member which supports table and the
head containing all mechanisms.
• Should be sufficiently rigid
• Column- round type, box column type
• Rack teeth are cut on the face of the column

16. Table
• Mounted on the column
• Provided with T slots
• Round or square in shape
• Vertical adjustment, radial adjustment about
the column, and circular adjustment about its
own axis.

17. Head
• Mounted on the top of the column
• Houses the driving and feeding mechanisms of
for the spindle.
• Some machines having provisions to adjust
the height of the head
• In lighter machines driving motor is placed at
the rear end of the head.

18. • Spindle and drill head
assembly
1. vertical shaft which holds the drill.
2. receives its motion from the top shaft .
3. Long keyway cut on the spindle and bevel
gear is connected.
4. Spindle rotates with in a non rotating
sleeve or quill.
5. Rack teeth are cut in the outer surface of
the sleeve.
6. Sleeve may be moved up or down by
rotating pinion.
7. Downward movement through thrust
bearing and washer.
8. Upward movement through thrust bearing
and nut.
9. Lower end of the spindle provided with
morse taper.
10. Slot is provided at the end of the tapered
hole.

19. Spindle drive mechanism
• By step cone pulley.
• By step cone pulley with one or more back
gears.
• By gearing.

20. • Step cone pulley drive
1. Motion is transmitted from an overhead
line shaft to the counter shaft.
2. Counter shaft may be started or stopped
by shifting fast pulley to loose pulley by
operating foot pedal.
3. Drill spindle receives power from over
head shaft .
4. Speeds may be varied by shifting the belt
on different steps of the cone pulley.

21. • By step cone pulley with
back gears.
18 and 16 are connected with the help
of belt 17.
14 and 16 attached together on a
hollow shaft.
Clutch 13 is keyed to shaft 10 .
24, 33 are the beck gears.
Spindle drive by gearing

22. 1. quick traverse hand feed
2. Sensitive hand feed.
automatic feed- 10 -11 to six speed
feed box.

23. parts
Base
Column
Radial arm
Drill head
Spindle speed and feed mechanism

24. • Base- large rectangular casting
- One end is support the column
- Other end is supports the work table
- Some m/c s has T slots
- When drilling is done on a job supported by
base the other job can be loaded on the work
table.

25. • Column- cylindrical casting that is mounted
vertically at one end of base.
- Supports the radial arm which may slide up or
down on its face.
- An electrical motor on the top of the column
which imparts vertical adjustment of the arm
by rotating a screw passing through a nut
attached to the arm

26. • Radial arm- it is mounted on the column
extends horizontally over the base
- Massive casting
- Front vertical face accurately machined to
provide the guide ways on which the drill head
may be made to slide.
- May be swung round the column
- Some m/c s this movement controlled by
separate motor.

27. • Drill head- it is mounted on the radial arm and
drives the drill spindle
- Encloses all the mechanisms
- Made to slide on the guide ways of the arm
for adjusting the position of the drill spindle

28. Work holding devices

29. T-bolts and clamps
Diameter of T-blots usually 15 to 20
mm.
Clamps or straps are made of mild
steel flats 12 to 20 mm thick and 45 to
7o mm wide.
A slot is cut at the centre of the strap
to allow T-bolts.
Types of clamps.
plain slot clamp
goose neck clamp
U-clamp.

30. Goose neck clamp
Used for holding work of sufficient.
Smaller size of T-bolts and packing
pieces can clamp the work securely.
Clamps are sufficiently strong.
Usually manufactured by forging.

31. U clamp
Useful for quick adjustment of the
work.
Clamp can be removed without
removing the nut.

32. Finger clamp
With round or flat extensions.
may be fitted with in hole of the work
piece for clamping

33. Adjustable step clamp
Has screw at one end which is used to
level the clamp when its other end
rests against the work.

34. Drill press vice
Used for holding regular shaped
workpieces.
Screw of the vise may be squre or
acme threaded.
parallel blocks are placed below the
work so that work may be pass
through the work without damaging
the vice table.
In universal vise the base may be
swiveled at any angle about the
vertical axis.

35. Step blocks
It used in conjunction with T-bolts
It can be used in holding various
heights work pieces.
Made of mild steel.

36. V-blocks
Used for holding round workpiecs.

37. Angle plates
Made of cast iron.

38. Drill jig
Used in mass production.
Hold the work.
Locate the work.
Guide the tool.

39. Tool holding devices

40. Directly holding the tool
Spindle bored out to a standard taper
to receive the taper shank of the tool.
Tool may be rotated with the spindle
by friction between the tapered hole.
Tongue of the tools fits into a slot at
the end of the taper hole.
Tool removed by pressing a drift.
Mallet should be used instead of
hammer.

41. Drill sleeve
Different sizes of tool shanks may be
held in spindle by using different
sleeve.
If the taper shank of the tool is smaller
than the taper in the spindle hole, a
taper sleeve is used.
Taper in outer surface does not
change.
The sleeve with the tool may be
removed by forcing a drift with in the
slot of the spindle.

42. Drill socket
When the tapered tool shank is larger
than the spindle taper drill sockets are
used to hold the tool.

43. Quick change chuck
Also known as magic chuck.
Used for locating series of tools one
after another without stopping the
spindle.
Body having the taper shank which is
fitted into the spindle.
Sliding collar is fitted with the loosely
on the rotating body
Sleeve (2) holding different tool may
be fitted on the body (1).
Balls (3) are placed in the holes
provided on (1)
The collar (4) is raised with one hand
the sleeve and the tool may be fitted
in the chuck body with the other hand.

44. Self centering chuck
It is particularly adapted for holding
tools having straight shanks.
Three slots are cut 120 degrees apart
and houses jaws having threads.
ring nut attached to the sleeve.
Bevel gear cut all round the sleeve
body.
Sleeve may be rotated by rotating a
key .

45. Floating holder
To follow a previous hole floating
holder is used.
Slot is cut at the cylindrical portion of
the body.
Cylindrical plate (2) has a key type
projection on one of its face which fits
into the slot of the shank body.
Another short key type projection
fitted on the sleeve (1).
(1) And (2) coupled by coupling (3).

46. operations
1 drilling
2. reaming.
3.Boring.
4.Counterboring.
5.Counter sinking.
6. Spot facing.
7.Tapping.

47. Operations in drilling machine

48. Drilling
• It removes the solid metal from the job to produce a circular hole.
• Before drilling, the hole is located by drawing two lines at right angles.
• Centre punch is used to make an indentation for the drill point
• The rotating drill is made to feed in the job
• Depending upon its length, may be drilled in one or more steps.
• Chips are cleared both from drill flutes and the job with the help of brush
Reaming
- It is a finishing operation.
- Carried out by a reamer
- Reamer is a multiple cutting edge tool
- Made up of hss or fitted with carbide cutting edges on its shank.
- Reamer can not produce hole in a solid job.
- It can accurately size and finish the already drilled holes.
- If the reaming operation is to be carried out on a job, the hole drilled in it is kept slightly undersize.
- Speed of the spindle made half that of drilling and automatic feed is employed for reaming the hole.

49. • Boring
- boring enlarges a hole, sizes it and finishes it.
- It is carried out when a drill of particular dimension is not available, when straight, accurate
hole is desired, or when holes need to be enlarged.
- Boring tool is held in boring bar which in turn is fitted into the drill spindle socket.
• Counter Boring
- Boring enlarges the holes to its full length but counter boring enlarges to a small length in
order to accommodate the heads of the bolts, studs.
- Counter boring tool has a pilot or guide that goes into the already drill hole and thus
maintains the alignment of the counter boring tool.
- It is held in the drill spindle.

50. • Counter sinking
- This operation bevels the mouth of a hole with a rotary tool called a counter sink.
- Cone shaped end of the hole accommodates a flat head screw or counter sink rivet fitted into the hole.
- Available in many styles and sizes, and with point angles.
• Spot facing
- It provides a locally machined, flat seating around a hole for nuts or bolt heads being pulled down onto
otherwise rough castings or forgings.
- The surface machined should be square with the hole.
Tapping
- It may be carried out on the drill press in order to cut threads in drilled hole
- When a large number of tapped , hand tapping is a slow process, and work is expedited by driving the tap
with the drilling machine, running on slow speed.
- Size- drilled hole smaller than the tap by twice the depth of the thread.

51. Twist drill nomenclature
• Drill axis is the longitudinal centre line.
• Drill point is the sharpened end of the drill body consisting of
all that part which is shaped to produce lips, faces and chisel
edge.
• Lip or cutting edge is the edge formed by the intersection of
the flank and face
• Lip length is the minimum distance between the outer corner
and the chisel-edge corner of the lip.
• Face is that portion of the flute surface adjacent to the lip on
which the chip impinges as it is cut from the work.
• Chisel edge is the edge formed by the intersection of the
flanks.

52. • Flank is that surface on a drill point which extends behind the
lip to the following flute.
• Flutes are the grooves in the body of the drill, which provide
lips, allow the removal of chips, and permit cutting fluid to
reach the lips.
• Flute length is the axial length from the extreme end of the
point to the termination of the flutes at the shank end of the
body.
• Body is that portion of the drill nomenclature, which extends
from the extreme cutting end to the beginning of the shank.
• Shank is that portion of the drill by which it is held and driven,

53. • Heel is the edge formed by the intersection of the flute
surface and the body clearance.
• Body clearance is that portion of the body surface reduced in
diameter to provide diametric clearance.
• Core or web is the central portion of the drill situated
between the roots of the flutes and extending from the point
end towards the shank; the point end of the core forms the
chisel edge.
• Lands are the cylindrically ground surfaces on the leading
edges of the drill flutes. The width of the land is measured at
right angles to the flute.

54. • Recess is the portion of the drill body between the flutes and
the shank provided so as to facilitate the grinding of the body.
Parallel shank drills of small diameter are not usually provided
with a recess.
• Outer corner is the corner formed by the intersection of the
lip and the leading edge of the land.
• Chisel edge comer is the corner formed by the intersection of
a lip and the chisel edge.
• Drill diameter is the measurement across the cylindrical lands
at the outer corners of the drill.
• Lead of helix is the distance measured parallel to the drill axis
between corresponding points on the leading edge of a flute
in one complete turn of the flute.

55. • Helix angle is the angle between the leading edge of the land
and the drill axis.
• Rake angle is the angle between the face and a line parallel to
the drill axis. It is bigger at the face edges and decreases
towards the center of the drill to nearly 0°. The result is that
the formation of chips grows more un-favorable towards the
centre.
• Lip clearance angle is the angle formed by the flank and a
plane at right angles to the drill axis; the angle is normally
measured at the periphery of the drill. To make sure that the
main cutting edges can enter into the material, the clearance
faces slope backwards in a curve. The clearance angle is
measured at the face edge, must amount to 5° up to 8°

57. Milling cutter nomenclature
• 1. OUTSIDE DIAMETER. The outside diameter is the diameter of the
cylinder passing through the peripheral cutting edges.
• 2. ROOT DIAMETER. The root diameter is the diameter of the circle
passing tangent to the bottom of the fillet.
• 3. SIDE TOOTH LENGTH. Length of the raised land along the side tooth.
Required to calculate the number of resharpenings available and the
modification possibilities.
• 4. CUTTER FACE WIDTH. The cutter face is the surface at the side or end of
the cutter body which is perpendicular to the axis of the cutter. The
distances between the two faces of plain, helical and side milling cutters,
or the length of the outside diameter cylinder is the cutter width, if small,
or cutter length,with respect to the diameter.
• 5. TOOTH FACE. The tooth face is that surface of the cutting tooth against
which the chip is forced in the metal cutting operation.

58. • 6. LAND. The land is that part of the back of the tooth adjacent to the
cutting edge which is relieved to avoid interference between itself and the
surface being machined. A raised land permits numerous resharpenings
before a secondary clearance has to be ground.
• 7. CUTTING EDGE. The cutting edge is the intersection of the face of the
tooth with the leading edge of the land.
• 8. FLUTE. The flutt, is the chip space between the back of one tooth and
the face of the following tooth.
• 9. RELIEF ANGLE. The peripheral relief angle is the angle between the
surface formed by the land and a tangent to the cutter outside circle
passing through the cutting edge in a diametral plane. It is to prevent the
land from rubbing on the surface of the work being cut. Relief and
clearance are measured in degrees or in radial fall in inches at a certain
specified distance back of the cutting edge on the land. For this latter
measurement, a dial indicator may be used to measure the radial fall in
thousandths of an inch from the outside or cutting edge diameter back of
the cutting edge.

59. • 11 AXIAL RAKE ANGLE OR HELICAL RAKE. When a milling cutter has
helical teeth, that is, when its cutting edge is formed along a helix about
the cutter axis, the resulting rake is called helicall rake. If the cutting edge
is straight, its rake is axial rake. The axial rake or helical rake angle is the
angle formed between the line of the peripheral cutting edge and the axis
of the cutter, when looking radially at the point of intersection. This
applies in the case of helical mills, half-side mills, staggered tooth mills,
face mills, and metal slitting saws having face cutting edges.
• 12. GASH DEPTH. Gash depth is the distance from the outside diameter of
the cutter to the fillet radius or root diameter.
• 13. FILLET RADIUS. The fillet radius is the curved surface at the bottom of
the flute which joins the face of one tooth to the back of the tooth
immediately ahead.
• 14. DISH OR CONCAVITY. The progressive decrease in cutter width from
the periphery toward the center.

60. • 15. RADIAL OFFSET. The radial offset of a milling cutter is the physical
dimension that a tooth is behind (for positive rake) or ahead (for negative
rake) of a center line drawn parallel with flat, tooth face. It is calculated by
multiplying the sine function of the radial rake angle times the radius of
the milling cutter.
• 16. DEPTH OF RECESS. The distance from the cutting edge on the land of
the side tooth (or the hub which is the same width as the cutter) to the
recess is the depth of recess. This dimension is required to determine
width and angle modification limits.
• 17. HUB DIAMETER. The hub is the raised ground section between the
bore and recess. It is the same width as the cutter. Collar spacers butt
adjacent to the hub for holding and spacing of the cutter on the arbor. The
hub diameter dimension is required to determine the allowable depth or
cut and clearance between cutter and workpiece.
• 10. RADIAL RAKE ANGLE. The radial rake angle of a milling cutter is the
angle formed in a diametral plane between the face of the tooth and a
radial line passing through the cutting edge. This may be positive,