Unit 3A6 - Shaper, planer, slotter

Machining & Machining Tools
Unit-3A6
General Purpose and Special Purpose
Machine Tools
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Shaper, Planer, Slotter

Shaper
INTRODUCTION
 Shaper is a machine tool used for removing metal
surfaces in horizontal, vertical and angular planes by the
use of a single point cutting tool held on the ram that
reciprocates the tool.
MACHINE FEATURES
 Single point cutting tool is used for machining .
 Tool is clamped in the tool post mounted on the ram of
the machine.
 The ram reciprocates to and fro; tool cuts the material in
the forward stroke, no cutting action during return or
back stroke.
 Job is held rigidly in a vice.
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Operations on Shaper
 Producing a flat surface on horizontal, a vertical or an
angular plane. With proper tools and accessories even
irregular surfaces can be formed.
 Making slots, grooves and keyways
 Producing contour of concave/convex or a combination
of these
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Working principle of Shaper
 A single point cutting tool is held in the tool holder that
is mounted on the ram.
 The workpiece is stiffly held in a vice or clamped directly
on the table.
 The ram reciprocates and cutting tool mounted in tool
holder moves forward and backward over the specimen.
 In a standard shaper, cutting of workpiece takes place
during the forward stroke of the ram (exception draw
type shaper). The backward stroke remains idle and no
cutting takes place throughout this stroke.
 The feed is given to the workpiece and depth of cut is
controlled by moving the tool downward towards the
workpiece.
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Working principle of Shaper
 The time taken throughout the idle stroke is less as
compared to forward cutting stroke and this is obtained
by quick return mechanism.
 In a shaping machine, a flat horizontal surface is
machined by moving the work mounted on the table in a
cross direction to the tool movement. When vertical
surfaces are machined, the feed is given to the tool.
When a inclined surface is machined, the vertical slide
of the tool head is swiveled to the required angle and the
feed is given to the tool by rotating the down feed hand
wheel.
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Working Principle
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Typical parts and surfaces machined on a shaper

Principle parts of Shaper
1. Base
2. Column
3. Cross-rail
4. Saddle
5. Table
6. Ram
7. Tool head
8. Clapper box
9. Apron clamping bolt
10. Down feed hand wheel
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11. Swivel base degree
graduations
12. Position of stroke
adjustment hand wheel
13. Ram block locking
handle
14. Driving pulley
15. Feed disc
16. Pawl mechanism
17. Elevating screw

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Base
 Rigid ,hollow and heavy cast iron body to resist vibration and
takes up high compressive load.
 Support to other parts
 Rigidly bolted to floor or on the bench
 Act as reservoir for supply of oil
Column
 A box shaped casting mounted upon the base.
 Made of cast iron
 Inside hollow for weight reduction
 Houses the ram-driving (quick return) mechanism inside
 Two guide ways on top on which ram reciprocates.
 Two guide ways at the front vertical face to move the cross
rail up and down along these guide ways.

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Cross rail
 box like structure over which the saddle slides horizontally.
 It is fixed on the front vertical guide ways of the column.
 It consists of mechanism for raising and lowering table by
rotating an elevating screw which causes the cross rail to
slide up and down on the vertical face of the column.
 A horizontal cross feed screw is fitted within the cross rail
which actuates the table to move in a crosswise direction.

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Saddle
 The saddle is located on the cross rail and holds the table on
its top.
 Crosswise movement of the saddle by rotation the cross feed
screw by hand or power causes the table to move sideways.
Table
 a box like casting having T -slots both on the top and sides
for clamping the work.
 bolted to saddle and receives crosswise and vertical
movements from the saddle and cross rail.
 Universal Table - it may be swiveled to the left or right and if
needed can be rotated to a full circle. A dial plate graduated in
degree indicates the angular setting. The top surface may be tilted
up to 15º forward or backward.

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Table Support or Out Board Clamp
 It gives an extra support to the table.
 It is fitted on the front side of the machine to take up the
cutting pressure as the tool cuts in forward motion.
 To lower or raise the table the clamping nuts of outboard
support is to be loosened.
Ram
 It is the reciprocating part of the shaper, which reciprocates
on the guide ways provided above the column.
 Ram is connected to the reciprocating mechanism
contained within the column.

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Tool head
1. It holds the tool rigidly,
2. It gives vertical and angular feed motion of the tool, and
3. It permits the tool to have an automatic relief during its
return stroke.
 The different parts of tool head of shaper are apron clamping
bolt, clapper box, tool post, down feed handle, micrometer
dial, down feed screw, vertical slide, apron washer, apron
swivel pin, and swivel base.

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 By rotating the down feed screw handle, the vertical slide
carrying the tool gives down feed or angular feed movement
while machining vertical or angular surface.
 The amount of feed or depth of cut can be controlled by a
micrometer dial on the top of the down feed screw.
 Apron
 Apron consisting of clapper box, clapper block and tool post is
fitted upon the vertical slide by a screw.
 The two vertical walls on the apron called clapper box houses
the clapper block, which is connected via hinge pin.
 The tool post is mounted upon the clapper block.
 On the forward cutting stroke the clapper block fits tightly to the
clapper box to make a rigid tool support.

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 On the return stroke a slight frictional drag of the tool on the
work lifts the block out of the clapper box a sufficient amount
preventing the tool cutting edge from dragging and
consequent wear. The work surface is also prevented from
any damage due to dragging.
 Pointer or Stroke Indicator - It indicates the length of
stroke. When tightened, it clamps the ram where by the
oscillating motion of the rocker arm is transferred to the ram
through the link lever. If it is not clamped, movement of
rocker arm will not be transferred to the ram.

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 Friction Quadrant or Automatic Movement of Vertical Tool -
This mechanism is incorporated in heavy machines to impart
automatic feed of the tool through the swiveling slide.
 Small Link - This link is connected to one end of the rocker arm
and the other end to the ram. The oscillating movement of rocker
arm through the link is converted into the reciprocating motion of
the ram. It is pivoted on the sides to give freedom of movement
when the rocker arm moves forward and backward.
 Rocker Arm or Long Link Lever - The rocker arm is pivoted at
the bottom of the machine, which carries the sliding block in its
slot. The rotary motion of the bull gear is converted into oscillating
motion of the rocker arm through the crank block, crank pin, and
sliding block.

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 Bull Gear - It is a big (generally helical) gear which carries the
mechanism and is driven by a pinion. On the face of this bull
gear, there is a dovetail way in which the crank block is held.
 Sliding Block - The block is made of wear resisting metal. It is
generally made out of bronze and slides in the slot of the rocker
arm with up and down movement
 Elevating Screw - It is used for raising and lowering the table.
 Stroke Adjustment Crank - Through this the stroke adjustment
is done by offsetting the crank block from the centre of the bull
gear to the required distance.
 Clapper Box - It is hinged on the swiveling slide and carries the
tool holder.

Types of Shapers
Based on type of mechanism employed for the movement
of the cutting tool i.e. tool carrying ram
a. Crank type
b. Gear type
c. Hydraulic type
According to position and movement of ram
a. Horizontal type
b. Vertical type
c. Travelling head type
Based on design of the work table
a. Standard shaper
b. Universal shaper
Based on type of cutting stroke employed
a. Push type
b. Draw type 24

Crank Shaper
Ram reciprocate by help
of a crank mechanism
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Geared Shaper
Ram reciprocate by rack and
pinion mechanism.

Hydraulic Shaper
 Reciprocating motion of the ram is achieved by hydraulic
power.
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According to position and movement of ram
Horizontal Shaper
• the ram holding the tool reciprocates in a horizontal axis.
Vertical Shaper called slotter
• the ram reciprocates in a vertical axis.
• mainly used for machining keyways, slots or grooves,
and internal surfaces.
Travelling Head Shaper
• the ram reciprocates and also moves crosswise to give
the specified feed.
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Based on design of worktable
Horizontal Shaper
• the ram holding the tool reciprocates in a horizontal axis.
Vertical Shaper
• the ram reciprocates in a vertical axis.
• mainly used for machining keyways, slots or grooves,
and internal surfaces.
Travelling Head Shaper
• the ram reciprocates and also moves crosswise to give
the specified feed.
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Based on type of cutting stroke employed
Standard Shaper
 In standard shaper, the table has only two movements,
horizontal and vertical, to offer the feed.
Universal Shaper
 A universal shaper is commonly employed in tool room
work. In this type of shaper, in addition to the horizontal
and vertical movements, the table can be move about an
axis parallel to the ram ways, and the upper portion of
the table can be tilted about a second horizontal axis
perpendicular to the first axis.
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Specification of Shaper
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 Generally the dimension of a shaper is specified by the
maximum length of stroke or cut it can make.
 Adjustable stroke
 Length of Ram
 Max. & Min. distance from Table to Ram
 Max. table travel (Horizontal & Vertical)
 Angular movement of table
 Max. vertical travel of tool slide
 Max. swivel of tool slide
 No. of ram speeds & range of speeds
 Range of table feed per stroke of ram
 Overall dimensions (Length, Width, Height)
 Net weight

Shaper Mechanism
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 In a standard shaper metal is removed in the forward cutting
stroke, while the return stroke goes idle and no metal is
removed during this stroke.
 The shaper mechanism is made so that it moves the ram
holding the tool at a comparatively slower speed during
forward stroke, whereas during the return stroke it allows the
ram to move at a faster speed to reduce the idle return time.
This mechanism is known as quick return mechanism.
 The reciprocating movement of the ram and the quick return
mechanism of the machine are generally achieved by
subsequent methods:
 Crank and slotted link mechanism
 Whitworth quick return mechanism
 Hydraulic shaper mechanism

Crank & Slotted Lever Mechanism
32

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 pinion receives its motion from an individual motor or
overhead line shaft and transmits the motion or power to the
bull gear.
 Bull gear is a massive gear fitted within the column. Speed of
the bull gear may be controlled via different combination of
gearing or by simply shifting the belt on the step cone pulley.
 A radial slide is fitted to the centre of the bull gear. This radial
slide includes a sliding block into which the crank pin is fitted.
 Position of slide block is adjusted (to obtain different stroke
lengths) by turning the stroke adjusting screw using bevel
gear.

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 Rotation of the bull gear will cause the crank pin to revolve at
a uniform speed.
 Sliding block, which is fitted upon the crank pin is fitted within
the slotted link. This slotted link is also called the rocker arm.
It is pivoted at its bottom end attached to the frame of the
column.
 The upper end of the rocker arm is forked and connected to
the ram block via a pin.
 With the rotation of bull gear, crank pin will revolve on the
crank pin circle, and simultaneously move up and down the
slot in the slotted link giving it a rocking movement, which is
communicated to the ram.
 Hence the rotary motion of the bull gear is converted to
reciprocating motion of the ram.

Crank & Slotted Lever Mechanism-Derivation
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In this mechanism, the
link AC (i.e. link 3)
forming the turning pair
is fixed. The link 3
corresponds to the
connecting rod of a
reciprocating steam
engine.
The driving crank CB
revolves with uniform
angular speed about the
fixed centre C.
A sliding block attached to the crank pin at B slides along the
slotted bar AP and thus causes AP to oscillate about the pivoted
point A.
A short link PR transmits the motion from AP to the ram which
carries the tool and reciprocates along the line of stroke R1R2. The
line of stroke of the ram (i.e. R1R2) is perpendicular to AC
produced.

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In the extreme positions, AP1
and AP2 are tangential to the
circle and the cutting tool is at
the end of the stroke.
The forward or cutting stroke
occurs when the crank rotates
from the position CB1 to CB2 (or
through an angle β) in CW
direction.
The return stroke occurs when
the crank rotates from the
position CB2 to CB1 (or through
angle α) in the CW direction.
Since the crank has uniform
angular speed, therefore,

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Note: From Fig. , we see that the angle β made by the forward or
cutting stroke is greater than the angle α described by the return
stroke. Since the crank rotates with uniform angular speed,
therefore the return stroke is completed within shorter time. Thus it
is called quick return motion mechanism.
Since the tool travels a distance of R1 R2 during cutting and
return stroke, therefore travel of the tool or length of stroke

Whitworth quick return mechanism
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In this mechanism, the link CD (link 2) forming the turning pair is
fixed. The link 2 corresponds to a crank in a reciprocating steam
engine.
The driving crank CA (link 3) rotates at a uniform angular speed.
The slider (link 4) attached to the crank pin at A slides along the
slotted bar PA (link 1) which oscillates at a pivoted point D. The
connecting rod PR carries the ram at R to which a cutting tool is
fixed. The motion of the tool is constrained along the line RD
produced, i.e. along a line passing through D and perpendicular
to CD.

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 When the driving crank CA moves from the position CA1 to CA2 (or the link
DP from the position DP1 to DP2) through an angle α in the clockwise
direction, the tool moves from the left hand end of its stroke to the right hand
end through a distance 2 PD.
 Now when the driving crank moves from the position CA2 to CA1 (or the link
DP from DP2 to DP1 ) through an angle β in the clockwise direction, the tool
moves back from right hand end of its stroke to the left hand end.

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 A little consideration will show that the time taken during the left to right
movement of the ram (i.e. during forward or cutting stroke) will be equal to
the time taken by the driving crank to move from CA1 to CA2. Similarly, the
time taken during the right to left movement of the ram (or during the idle or
return stroke) will be equal to the time taken by the driving crank to move
from CA2 to CA1.
 Since the crank link CA rotates at uniform angular velocity therefore time
taken during the cutting stroke (or forward stroke) is more than the time
taken during the return stroke. In other words, the mean speed of the ram
during cutting stroke is less than the mean speed during the cutting and
return strokes is given by
Note. In order to find the length of effective stroke R1 R2, mark P1 R1 = P2
R2 = PR. The length of effective stroke is also equal to 2 PD.

Hydraulic shaper mechanism
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Hydraulic mechanisms are becoming increasingly popular
because of the following advantages:
 Greater flexibility of speed.
 Smoother operation.
 Ability to slip in case of overload.
 Ability to withstand against an obstruction without damage to
the tool or the machine.
 Possibility of changing speed and feed during operation.
 Velocity diagram of hydraulically operated shaper shows a very
nearly constant velocity as compared with the crank shaper as
shown in Fig.

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•A gear pump driven by an electric
motor pump supplies constant
quantity of oil at a moderate
pressure from reservoir and
deliver to cylinder through
control valve.
•By changing the position of the
control valve lever, the oil is
delivered to the right or left side
of the piston.
.
 In the position P1 , oil is delivered to left side of cylinder. Due to
oil force, piston moves from left to right. It is cutting stroke.
 At the same time, oil in right side (supplied in the previous
stroke) flows out of cylinder which goes to the reservoir through
the control valve.

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•When the lever is in position P2,
oil is delivered to the right side of
piston. It moves the ram from right
to left. It is return stroke.
•At the same time, the oil on the left
side of the cylinder (it is delivered
during the previous stroke) goes
to the reservoir through the
control valve. The position P1 and
P2 can be adjusted by adjusting
trip dogs.
 The length of stroke and position of stroke is adjusted by
adjusting the position of the trip dogs. Cutting speed in cutting
stroke is controlled by adjusting the throttle valve. Full opening
of this valve give more speed. Partial opening give less speed.

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There is a relief valve. It
releases the pressure when it
is more than system pressure.
Quick Return: The piston rod
is provided in the right side. It
occupies certain volume. So
less volume of oil can be filled
up in the right side. But the
pump pumps the oil at
constant rate. Hence, when
the oil enters from right side,
it gives more force. During the
return stroke, the ram moves
fast

Feed Mechanism-Hand Feed
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 At the end of return stoke feed is
given, known as feed
mechanism.
 Three types-horizontal, vertical
& inclined feed
 By down feed screw vertical and
angular feeds
 Cross feed by horizontal
movement of table using cross
feed screw
 The screw is engaged with a nut
fitted in table. When screw is
rotated by handle , table moves
horizontally on cross rail.
 If rotated by hand then called
hand feed

Automatic Table feed- Pawl & Ratchet Mechanism
49
A ratchet wheel is keyed to the feed
screw. A rocker arm is fulcrumed at
the centre of the ratchet wheel. It
has a spring loaded pawl at its top.
The pawl has bevel shape on one
side and straight flat shape on
another side.
The rocker arm is connected to a
driving disc by a connecting rod.
The driving disc has a T slot on its
face along its diameter. A crank pin
fits into the slot. The position of
crank pin can be adjusted in the
radial direction of the disc. The pin
is fitted with one end of the
connecting rod.

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 The driving disc gets the drive
from the bull gear. As the disc
rotates , the rocker arm rocks
(oscillates) on the fulcrum.
When the disc makes half
revolution in clockwise
direction, the top part of rocker
arm moves in CW direction. As
the bevel side of pawl, fits on
right side, the pawl slips over
the teeth of rachet wheel. It
gives no movement to the table.
 During the other half of rotation,
the top part of rocker arm
moves in anticlockwise direction
.

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 The straight side of the pawl
positioned on the left side
engages with the teeth of ratchet
wheel . It rotates the ratchet
wheel in ACW the feed screw
rotates and the table moves.
This movement takes place only
during the return stroke.
 To get reverse feed , the pawl is
turned through 180 after lifting
the pawl . Now the bevel side fits
on the left side and the straight
side on the right side.
 Amount of cross feed is varied
by changing the position of
crankpin in the radial direction
of disc.

Shaper Operations
52
Regular operations
 Machining horizontal surfaces
 Machining vertical surfaces
 Machining angular surfaces
 Machining dovetail groove
 Machining V block
 Machining a tongue and groove joint
 Machining external keyways
 Machining internal keyways
 T-slot machining
 Machining splines or cutting gears
 Machining irregular surfaces

Machining Horizontal Surfaces
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 By moving the work mounted
on the machine table at a cross
direction with respect to the
ram movement.
 The clapper box can be set
vertical or slightly inclined
towards the uncut surface.
 This arrangement enables the
tool to lift automatically during
the return stroke. The tool will
not drag on the machined
surface

Machining Vertical Surfaces
54
 A vertical cut is made while
machining the end of a
workpiece, squaring up a block or
machining a shoulder.
 The feed is given to the tool by
rotating the down feed screw of
the vertical slide. The table is not
moved vertically for this purpose.
 The apron is swiveled away from
the vertical surface being
machined as shown in the
diagram.

Machining Angular Surfaces
55
Machining the inclined (angular) surfaces can be done in several
ways. They are
Taper strip method – The taper strip is positioned on the table
and fixed. On the taper strip, the job is fixed and machined. The
angular surface is obtained.
Layout method – Slanting surface is marked on the work piece.
The job is positioned by suitable arrangement in such a way that
the marked line is either horizontal or vertical. If the machining is
carried out, the required angular surface is obtained.
Degree parallel method – Degree parallel block is a wedge
shaped precision block for a particular angle. The degree parallel
block is placed first on the table. Over and above that, the
workpiece is positioned and the machining is done as usual to
obtain the required angular surface.

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Universal vice method – The job may be fixed in the universal
vice and then the vice is swiveled to the required angular position.
If the machining is carried out, the required slanting (angular)
surface will be obtained.
Universal table method – If the universal table is available in the
shaping machine, then the table can be tilted to the required
position and the work is fitted on that. The machining is done as
usual to obtain the required angular surface.

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Swivel toolhead method – An
angular cut is made at any angle
other than a right angle to the
horizontal or to the vertical
plane. The work is set on the
table and the vertical slide of the
toolhead is swiveled to the
required angle either towards
left or towards right from the
vertical position. The apron is
then further swiveled away from
the work to be machined.

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Machining dove tail groove
 Dove tail joint is machined on two separate pieces of work as
male and female elements.
 The required shape is marked on the face of the work and the
unwanted metal is first removed by the round nose tool. A
special form tool is used to finish the machining

Special Operations
59
Machining a ‘V’ block
The required shape of a ‘V’ block is
marked on the face of the work and
machining is done by any suitable
method of angular machining.
Machining a tongue and groove joint
The male and female elements of the
tongue and groove joint having
vertical surfaces is machined after
the exact shape is marked on the
face of the work.

Machining External Keyways
60
Machining external keyways refers to the cutting of long slots along
the length of cylindrical rods. Initially a round nose tool is used and
then a square nose tool is used to finish the operation. A hole of
depth equal to the depth of the keyway is made at the blind end to
leave a clearance to the tool at the end of the stroke. When a
keyway is cut at the middle of the shaft, holes are drilled at both
ends of the keyway.

Machining Internal Keyways
61
Internal keyways are cut inside the holes of gears and pulleys. It is
done by holding the tool on a special tool holder called ‘snout bar’.
The snout bar is directly fitted on the clapper block.

Special Operations
62
T-slot Machining
 The shape of the T-slot is marked on
the face of the work.
 A parting off tool is fitted on the tool
post and a rectangular slot is
machined at the middle for the
required depth.
 The broad base of the ‘T’ slot is
machined by a T-slot cutting tool.
Machining a Rack Gear
process of cutting teeth elements at
linear pitch on a flat piece of work.
Firstly, the groove is machined with a
square nose parting tool.
Then, the groove is further machined
with a form tool conforming the shape of
the teeth.

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Machining Irregular Surfaces
 A shaper can also produce a contoured
surface using a round nose tool.
 To produce a small contoured surface a
forming tool is used.
 If the curve is sufficiently large, powered
cross feed along with manual down feed is
so adjusted that the tool will trace the
required contour
Irregular or Contour Cutting
 It calls for simultaneous operation of
horizontal table feed as well as vertical
hand feed of the cutting tool.
 It can be performed only by a very
skilled operator.

Machining Splines or cutting gears
64
 Using an indexing mechanism a gear or splines can be cut. Splines
are multiple keys integral with the shaft or hub. The WP is held
between centres. First a spline (keyway) is cut and the WP is
rotated through a predetermined amount and locked in position
using an index plate and pin Now the second spline is cut and the
WP is indexed for the next spline.
 In a similar way gears can also be cut using a form tool whose
profile resembles the space between a pair of teeth.

Machining Parameters-Shaper
65
CUTTING SPEED
 In a shaper, the cutting speed is the rate at which the metal is
removed by the cutting tool. This is expressed in meters per
minute.
 It is defined as the no. of cutting strokes, which the ram makes
per minute.
 In shaper, average cutting speed is considered as no cutting
takes place in return stroke.
 Harder the metal or deeper the cut, slower is the cutting speed.
 Softer the metal or lighter the cut, higher is the cutting speed.

CUTTING SPEED CALCULATIONS
66
 Difficult to measure time taken during the forward cutting stroke.
 So Let,
 L = the length of cutting stroke in mm
 m = the ratio between return time to cutting time
 n = the number of double stroke of the ram per minute or rpm of
the bull gear
 V = Cutting speed expressed in m/min
 From the equation number (I)
Cutting Speed=
𝐋𝐞𝐧𝐠𝐭𝐡 𝐨𝐟 𝐂𝐮𝐭𝐭𝐢𝐧𝐠 𝐒𝐭𝐫𝐨𝐤𝐞
𝐓𝐢𝐦𝐞 𝐑𝐞𝐪𝐮𝐢𝐫𝐞𝐝 𝐛𝐲 𝐂𝐮𝐭𝐭𝐢𝐧𝐠 𝐒𝐭𝐫𝐨𝐤𝐞
−− −(𝟏)
Time taken by Cutting Stroke=
𝐋𝐞𝐧𝐠𝐭𝐡 𝐨𝐟 𝐜𝐮𝐭𝐭𝐢𝐧𝐠 𝐬𝐭𝐫𝐨𝐤𝐞
𝐢𝐧 𝐦𝐞𝐭𝐫𝐞
𝐂𝐮𝐭𝐭𝐢𝐧𝐠 𝐬𝐩𝐞𝐞𝐝
𝐢𝐧 𝐦/𝐦𝐢𝐧
=
𝐋
𝟏𝟎𝟎𝟎× 𝐕

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 Difficult to measure time taken during the forward cutting stroke.
 So Let,
 L = the length of cutting stroke in mm
 m = the ratio between return time to cutting time
 n = the number of double stroke of the ram per minute or rpm of
the bull gear
 V = Cutting speed expressed in m/min
 From the equation number (I)
Cutting Speed=
𝐋𝐞𝐧𝐠𝐭𝐡 𝐨𝐟 𝐂𝐮𝐭𝐭𝐢𝐧𝐠 𝐒𝐭𝐫𝐨𝐤𝐞
𝐓𝐢𝐦𝐞 𝐑𝐞𝐪𝐮𝐢𝐫𝐞𝐝 𝐛𝐲 𝐂𝐮𝐭𝐭𝐢𝐧𝐠 𝐒𝐭𝐫𝐨𝐤𝐞
−− −(𝟏)
Time taken by Cutting Stroke=
𝐋𝐞𝐧𝐠𝐭𝐡 𝐨𝐟 𝐜𝐮𝐭𝐭𝐢𝐧𝐠 𝐬𝐭𝐫𝐨𝐤𝐞
𝐢𝐧 𝐦𝐞𝐭𝐫𝐞
𝐂𝐮𝐭𝐭𝐢𝐧𝐠 𝐬𝐩𝐞𝐞𝐝
𝐢𝐧 𝐦/𝐦𝐢𝐧
=
𝐋
𝟏𝟎𝟎𝟎× 𝐕

68
𝐦 =
𝐑𝐞𝐭𝐮𝐫𝐧 𝐬𝐭𝐫𝐨𝐤𝐞 𝐭𝐢𝐦𝐞
𝐂𝐮𝐭𝐭𝐢𝐧𝐠 𝐬𝐭𝐫𝐨𝐤𝐞 𝐭𝐢𝐦𝐞
Or Return stroke time = m× 𝐂𝐮𝐭𝐭𝐢𝐧𝐠 𝐬𝐭𝐫𝐨𝐤𝐞 𝐭𝐢𝐦𝐞 =
𝐦×𝐋
𝟏𝟎𝟎𝟎×𝐕
Time taken to complete one double stroke(t)=
𝐋
𝟏𝟎𝟎𝟎𝐕
+
𝐦𝐋
𝟏𝟎𝟎𝟎𝐕
=
𝐋(𝟏+𝐦)
𝟏𝟎𝟎𝟎𝐕
Number of double stroke per minute =
𝟏
𝐋(𝟏+𝐦)
𝟏𝟎𝟎𝟎𝐕
Or RPM of the bull gear (n) =
𝟏𝟎𝟎𝟎𝐕
𝐋(𝟏+𝐦)
=
𝐧𝐋(𝟏+𝐦)
𝟏𝟎𝟎𝟎𝐕
The cutting speed so calculated is the average cutting speed as it has been
assumed that the cutting stroke is completed at the uniform speed. But, in
reality, in a crank driven shaper cutting speed and return speed are not
uniform.

69
FEED
Feed is the relative movement of the tool or work in a
direction perpendicular to the axis of reciprocation of the
ram per double stroke and is expressed in mm. The feed
is always given at the end of the return stroke when the
tool is not cutting the metal. The selection of feed is
depending upon the kind of metal, type of job, etc.
DEPTH OF CUT
Depth of cut is the thickness of metal that is removed in
one cut. It is perpendicular distance measured between
machine surface and non-machine surface of the work
piece.

70
MACHINING TIME
If the length of cutting stroke, breadth of job, feed and cutting speed
is known, the time required to complete the job may be calculated as
follows:
Let
L = the length of stroke in mm
B = the breadth of work in mm
s = feed expressed in mm/ double stroke
m = the ratio of return time to cutting time
V = the cutting speed is meter / minute Then from equation …… (II),

Vices
72
(d) Plain vice - Plain vice is bolted
to the machine table. It holds the
work piece securely while
machining.
(e) Universal Vice - This type of
vice can be swiveled at any
desired angle through a horizontal
plane. It can be tilted and held
stationary at an angle from the
horizontal to the vertical by means
of a hinged knee. Work is
supported between the centres of
dividing head.

Clamping directly on Table
73
Using a Step block and Strap clamps
 WP is clamped to the surface of table by strap clamp
 Head of T bolt fits into T slot & other end of the clamp is
put on a step block. Clamp rest on the step whose height
is approximately equal to WP height
 Clamp is tightened using nut & T bolt should be placed
near to WP
 A number of clamps are used to hold large WP

74
Using strip and stop pins
 A strip is long piece of rectangular section. At bottom it has
a lengthwise projection. This projection fits into the T slot
of table.
 There are a number of holes in the strip. Using these holes ,
the strip is clamped to the table by means of T bolts. The
WP butts against the side of the strip plate.
 At the other side of the WP, stop pins are fitted in the T slot.
The stop pin screws are tightened to clamp the WP . This
method is used for holding thick WP.

75
Using a wedge strip and stop pins
 This method is used for holding large cylindrical WP. The wedge strip has
tong (projection) at its bottom. It fits into the T slot of the table. The wedge
strip is held in position by a T-bolt.
 At the other side of the WP a stop pin is fitted into the table. A wedge block
is placed between the work and stop pin. The stop pin screw is tightened
to clamp the WP. A filler block is placed between stop pin and wedge block
to avoid slipping of wedge block while clamping.

76
Clamping over a V block
 For holding small cylindrical WPs. Two V blocks may be used for longer
WPs
 WP is placed over V block
 It is clamped to the table by a clamp & T bolts

77
Fixture
 Figure shows a fixture for cutting internal keyway in a hallow WP. The
fixture is clamped to the table using T bolts. The WP is located by means
of a V block fitted to the fixture.
 The WP is clamped in position by a screw.
 A special tool holder is used so that the tool post will not hit against the
work

Angle Plate
78
 Used to clamp workpieces of irregular shapes and having holes.
 Clamped to the top of table by T bolts
 WP is clamped to the vertical face of angle plate
 A packing strip may be used to support WP at the bottom

Workholding Devices: Types of Clamps
79
Gooseneck Clamp
Adjustable Plain Clamp Adjustable Gooseneck Clamp
Screw heel clamp

Slotter
82
The slotting machine is a reciprocating machine tool in
which, the ram holding the tool reciprocates in a vertical
axis and the cutting action of the tool is only during the
downward stroke. The workpiece is held stationary
Construction: The Slotter can be considered as a
vertical shaper and its main parts are:
1. Base, column and table
2. Ram and tool head assembly
3. Saddle and cross slide
4. Ram drive mechanism and feed mechanism.

Slotter
86
Base
 Cast iron bottom casting to take compressive loads and to
support entire Slotter structure.
 On top horizontal guide ways which enables the saddle to
move perpendicular (near & away) to the column.
Column
 Cast iron vertical member integral to base
 Houses driving mechanism.
 Vertical front face has guideways for up-down motion of ram
Saddle
 Mounted on top guideways of base
 On its top face guide ways for cross slide. Perpendicular to
guideways present in base.
Cross Slide
 Mounted on saddle and movement is parallel to the column
face.

Slotter
87
Rotary table
 Circular shaped
 Mounted on top of the cross slide.
 Can be rotated about a vertical axis. Amount of rotation is
called circular feed
 Hand wheels are provided for longitudinal, cross and rotary
movements of the table.
 All the feeding systems are graduated.
 T- slots are being provided on the table for holding the work
piece.
 The longitudinal feed of the saddle, the cross feed of the
cross slide and the rotary movement of the table in all these
feeding mechanism the feed can either be given by hand or
by power.

Slotter
88
Ram
 Ram carry cutting tool at bottom and provide reciprocating
motion in vertical direction
 This reciprocation is achieved by the quick return
mechanism.
Counter weight
 Acts as a balancing weight for the ram during the operation
and prevents jerky action of the ram
Cone Pulley
 driving pulley to which power is applied from an external
source to drive the Slotter.
 The steps provide a different speed of driving.
Drive Pinion
This is keyed to the cone pulley shaft and meshes with large
bull gear

Slotter
89
Bull Gear - This gear is much larger than the drive pinion and
gives the necessary relative speed reduction between the cone
pulley and crank disc.
Crank Disc - The disc is keyed to the bull gear shaft and
revolves with it.
Crank - The crank is movably mounted in a radial slot in the
crank disc to which it can be rigidly clamped.
Stroke Adjustment Screw - By turning screw one way or the
other, it may be moved towards or away from the crank disc,
centre, thus shortening or lengthening the ram stroke.
Connecting Rod - This link connects the ram and crank and
changes the rotary motion of the crank into the reciprocating
motion.

Types of Slotter
90
1. Punch Slotter: a heavy duty rigid machine designed
for removing large amount of metal from large forgings
or castings
2. Tool room Slotter: a heavy machine which is
designed to operate at high speeds. This machine
takes light cuts and gives accurate finishing.
3. Production Slotter: a heavy duty Slotter consisting of
heavy cast base and heavy frame, and is generally
made in two parts.

Workholding devices
91
Vices , T Clamps, Parallel
Strips, Special Jigs and
Fixtures ,rotary table,
indexing head etc. Packing
pieces for over travel of
tool.

Operations on Slotter
92
 The slotting machine can be used to cut slots, splines
keyways for both internal and external jobs such as
machining internal and external gears.
 It can be used for shaping internal and external forms or
profiles.
 It can be used for works as machining concave, circular,
semi-circular and convex surfaces.
 It can be used for machining vertical surfaces, machining
angular or inclined surfaces, machining of shapes which are
difficult to produce on a shaper machine and machining dies
and punches.
 It can be used for internal machining of blind holes.

Specifications
93
 The maximum stroke length
 Diameter of rotary table
 Maximum travel of saddle and cross slide
 Type of drive used
 Power rating of motor
 Net weight of machine
 Number and amount of feeds
 Floor area required

Quick return mechanism
94
Metal from the work piece is removed only during the
cutting stroke. During the return stroke no metal is being
removed. To reduce the idle time of the return stroke quick
return mechanisms are being used. The following are the
generally used quick return mechanisms in a slotting
machine.
 Whitworth quick return mechanism.
 Variable speed reversible electric motor drive.
 Hydraulic drive.
All these mechanisms have been explained already in
shaper mechanisms

Planers
96
 Shapers are not suitable for large workpieces because of
overhang and short stroke .
 Hence large work-pieces are handled on the planer because
of its capacity of long table travel and robust construction.
 In case of shaper, reciprocating motion is given to the cutting
tool whereas in case of planer the work reciprocates and tool
is given the feed.
 The surface machined may be horizontal, vertical or at an
angle.
 The planer is used for:
Planing flat horizontal, vertical and curved surfaces.
Planing at an angle and machining dovetails.
Planing slots and grooves.

Working Principle
97
In a planer the work which is supported on the table reciprocates
past the stationary cutting tool and the feed is imparted by the
lateral movement of the tool. The tool is clamped in the tool holder
and work on the table. Like shaper, the planner is equipped with
clapper box to raise the tool in idle stroke.

Types of Planer
98
According to general construction, these are the following
types
 Double Housing Planer
 Open Side Planer
 Pit Type Planer
 Divided Table Planer
 Edge Type Planer

Double Housing Planer
100
1. Bed
The bed is a long heavy base and table made of cast iron. Its top
surface is flat and machined accurately. The flat top surface has slots
in which the workpiece can be securely clamped. The workpiece
needs rigid fixing so that it does not shift out of its position. The
standard clamping devices used on planer machine are: Heavy duty
vice, T-holders and clamps, angle plate, planer jack, step blocks and
stop. The table movement may be actuated by a variable speed drive
through a rack and pinion arrangement, or a hydraulic system.
2. Table
It is also a box type structure which reciprocates on the bed guide
ways. It is also having ‘T’ slots as that of shaper for clamping the
work piece.

101
3. Columns
The two long structural member along with guide ways
provided on both sides of the member. The two long
columns linked by a cross rail and cross beam. The cross
rail moves on the guide ways. It carries feed mechanism
and power transmission links.
4. Cross rail
It is a rigid structural member mounted between two
columns and slides on the guide ways already provided on
the columns. The cross-rail can be fixed or fastened at any
height. It moves tool heads.

102
5. Tool heads
Maximum four tool heads can be mounted on the planer.
Two on the cross rail and the other two are on the guide
ways of both the columns. It may tilt to any essential angle.
6. Driving and feed mechanism: The tool heads may be
fed either by hand or by power in crosswise or vertical
direction. The motor drive is usually at one side of the
planer near the centre and drive mechanism is located
under the table.

Open Side Planer
104
Only one supporting column, less rigid, Three tool heads,
two on cross-rail and one on column, main advantage is
that work may be extended out over the bed and large,
heavy & wide work pieces can be machined.

Pit Type Planer
105
 Table and the work piece resting on it remain stationary and
the tool reciprocates across the work surface.
 Preferred for very large work, where the weight of the work
piece and the table would make reciprocating movement
difficult.
 The job is either mounted on a stationary table, or on the floor
inside a pit, and hence the name pit type planer.
 One or two tool heads can be mounted on the cross rail and
two side tool posts on the housings, if required.
 The entire unit travels along the horizontal ways to and fro,
thus the tool moves past the work surface during operation.

Divided Table Planer
107
 It is also called tandem planer and consists of two
worktables, which may be reciprocated together or
separately.
 When mounting and setting of work pieces on the
worktable consumes more time thereby restricting the
machine for continuous mass production applications,
divided table planer can be used.
 In this, one worktable can be used for setting up a new
workpiece, while the second worktable carrying workpiece
is being machined.
 The two tables can be joined together to hold large work
pieces.

Edge Type/ Plate Type Planer
108

Edge Type/ Plate Type Planer
109
 This type of machine is used for machining the
edges of heavy work pieces.
 The work piece is clamped on the bed and the side
mounted carriage supporting the cutting tool is
reciprocated along the edge of the work piece.
 Cutting can take place during both directions of
carriage travel.

Comparison Table Shaper Planer Slotter
110
Aspect Shaper Planer Slotter
1. Work-tool
Motion
Tool
reciprocates
in horizontal
axis and work
feeds
intermittently
Work
reciprocates in
horizontal axis
and tool feeds
intermittently
Tool
reciprocate
s in
vertical
axis and
work feeds
intermitten
tly
2. Constructio
n & Rigidity
Lighter in
construction
& less rigid
Heavier in
construction
and more rigid
Lighter in
constructio
n & less
rigid

111
3. Motor
power
required
Relatively less
power
Higher power
compared to
shaper
Relatively
less power
4. Typical
work size &
set up time
Relatively
small parts,
Quick set-up
time
Bigger parts
require lengthy
set up time
Relatively
small
parts,
Quick set-
up time
5. No. of
surfaces
that can be
machined
at a time
Only one
surface at a
time
Three surfaces
can be
machined at a
time
Only one
surface at
a time

112
6. Material
removal
rate
(MRR)
Low MRR High since
multiple tools
can work at a
time
Low MRR
7. Tool Size Regular size
similar to lathe
Bigger size
tools that can
take higher
depth of cut
and feed
Regular size
similar to
lathe
8. Range of
speed and
feeds
Smaller range
and smaller
number of
speeds and
feeds
Wide range and
more number of
speeds and
feeds available
Smaller
range and
smaller
number of
speeds and
feeds

Unit 3A6 - Shaper, planer, slotter

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Unit 3A6 - Shaper, planer, slotter