The document describes the modeling, fabrication, and assembly of a Geneva wheel mechanism. It discusses generating a 3D CAD model, selecting materials, machining parts using both conventional and CNC machines, inspecting and finishing the components, and finally assembling the mechanism. The methodology involves modeling the design in NX Unigraphics, machining aluminum parts on a lathe and milling machine, programming and machining with a CNC center, and assembling the drive wheel, driven wheel, and base plate using bolts and nuts.

1. 1
MODELLING AND FABRICATION OF GENEVA
WHEEL MECHANISM
PRESENT BY
VIGNESHWARAN V B.E

2. OBJECTIVE
• To Fabricate And Assemble A Working Model Of An Existing
Geneva Wheel Mechanism Model.
• To Design The Geneva Mechanism Model Using Unigraphics-
Nx Cad 9.0
• To Study The Conventional Machines And Cnc Machining Centres.
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3. 3
METHODOLOGY
GENERATE GENEVA MECHANISM IDEA(AIM)
3D MODELING OF GENEVA MECHANISM
MATERIAL SELECTION
PROCESS PLANING OF GENEVA MECHANISM
ADVANCED MACHINING PROCESS USING CNC PROGRAMMING
FABRICATION OF PARTS
ASSEMBLY
WORKING CONDITION (ACHIEVE THE GOAL)

4. 4
INTRODUCTION
• The Geneva mechanism translates a
continuous rotation into an
intermittent rotary motion.
• The rotating drive wheel has a pin
that reaches into a slot of the driven
wheel.
• The drive wheel also has a raised
circular blocking disc that locks the
driven wheel in position between
steps

5. 5
MODELLING OF GENEVA WHEEL
COMPUTER-AIDED DRAFTING (CAD):
•It is the use of computer systems to assist in the creation,
modification, analysis, or optimization of a design
• To Increase the Productivity Of the Designer
•Improve the Quality Of Design
•Improve Communications Through Documentation
• To Create A Database For Manufacturing
•To Generate the 3-d Model By Using Nx Unigraphics Software.
•Model is a Representation of an object, a system, or an idea in
some form other than that of the entity itself

6. 6
`
MODELLING OF GENEVA WHEEL
TWO DIMENSIONAL MODEL OF ROTATOR TWO DIMENSIONAL MODEL OF GENEVA WHEEL

7. MODELLING OF GENEVA WHEEL
7TWO DIMENSIONAL MODEL OF BASE PLATE

8. 3-D MODELLING OF GENEVA WHEEL
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9. MATERIAL SELECTION
RAW MATERIAL:
•Rotator circle plate - Aluminium
•Geneva wheel - Aluminium
•Rectangular Base plate - Aluminium
•Bolt (2 nos) - Galvanized iron coating
•Nut(4nos) - Galvanized iron coating
•Bushes (4nos) - Plastic
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10. MATERIAL SPECIFICATION
S.NO NAME OF THE PART LENGTH
(mm)
BREADTH
(mm)
THICKN
ESS
(mm)
DIAMETER
(mm)
1 Rectangular base plate 270 200 12
2 Rotator circle plate 25 150
3 Geneva wheel Cut From rectangular plate
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11. PRE MACHINING PROCESS
HACKSAW PROCESS:
A power hacksaw (or electric hacksaw) is a type of
hacksaw that is powered either by its own electric motor
or connected to a stationary engine.
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12. PRE MACHINING PROCESS
FILING PROCESS:
Filing helps achieve work piece function by
removing some excess material and deburring
the
surface.
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NAME OF THE PART DIMENSION BEFORE FILING AFTER FILING
Rectangular base plate Length 270 mm 268mm
Thickness 12mm 11.5 mm
Breadth 200mm 196 mm
Square plate Length 116mm 115.5mm
Thickness 12mm 11.5 mm
Breadth 116mm 115.5mm

13. PRE MACHINING PROCESS
FACING PROCESS:
Machine: Lathe (three jaw chuck)
Workpiece: Geneva Rotator
Cutting Tool: High Speed Steel
Facing is the process of removing metal from the
end of a workpiece to produce a flat surface
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WORKPIECE HOLDING ALLEN NUT BOLT
SUPPORT
NAME OF
THE PART
DIMENSI
ON
BEFORE
FACING
AFTER
FACING
Rotator
circular billet
Length 25mm 20mm

14. PRE MACHINING PROCESS
TURNING PROCESS:
Machine: Lathe (three jaw chuck)
Workpiece: Geneva Rotator
Cutting Tool: High Speed Steel
Turning is used to reduce the diameter of the workpiece
usually to a specified dimension and to produce a smooth
finish on the metal
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NAME OF THE
PART
DIMENSION BEFORE
TURNING
AFTER
TURNING
Rotator circular
billet
diameter 150 mm 140 mm

15. PRE MACHINING PROCESS
MILLING PROCESS:
Machine: Vertical milling machine
Workpiece: Geneva Rotator,wheel,baseplate
Cutter: Facemill cutter
Milling is a cutting process that uses a milling cutter to
remove material from the surface of a workpiece.
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NAME OF THE
PART
DIMENSION
BEFORE
MILLLING
(in mm)
AFTER
MILLING
(in mm)
Geneva wheel
Length 115.5 115
Breadth 115.5 115
Thickness 11.5 10
Rectangular base
Length 268 266
Breadth 196 191

16. MACHINING PROCESS
CNC MILLING PROCESS:
•Computer Numerical Control (CNC) is one
in which the functions and motions of a machine
tool are controlled by means of a prepared
program containing coded alphanumeric data.
•CNC can control the motions of the work
piece or tool, the input parameters such as feed
depth of cut, speed, and the functions such as
spindle on/off, coolant on/off.
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17. CNC MILLING PROCESS:
PROGRAM STRUCTURE:
• G-Codes
• M-codes
• Absolute coordinate system
• Incremental system
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18. CNC MILLING PROCESS
NAME OF
THE PART
DIMENSION
BEFORE
MILLLING
(in mm)
AFTER
MILLING
(in mm)
Geneva
wheel
Length 115 113.1
Breadth 115 113.2
Thickness 10 8.1
Rotator Diameter 140 130
Thickness 20 15
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19. INSPECTION
• Vernier caliper
• Micrometer
• Dial gauge
• Bevel protactor
• Flatness
• Straightness
• Perpendicularity
• Parallelism
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20. FINSHING PROCESS
20
NAME OF THE
PART
DIMENSION
BEFORE
MACHINING
(in mm)
AFTER
MACHINING
(in mm)
Geneva wheel
Length 113.1 113
Breadth 113.2 113
Thickness 8.1 8
Rectangular base
plate
Length 266 265
Breadth 191 190
Thickness 12 10
Rotator Diameter 130 129
Thickness 15 14

21. ASSEMBELY OPERATION
PARTS:
•DRIVE WHEEL
•DRIVEN WHEEL
•BASE PLATE
•BOLT
•NUT
•BUSHES
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22. ADVANTAGES OF GENEVA MECHANISM
• Geneva mechanism may be the simplest and least Expensive of all intermittent motion
mechanisms.
• They come in a wide variety of sizes, ranging from those used in instruments, to those used in
machine tools to index spindle carriers weighing several tons.
• They have good motion curves characteristics compared to ratchets, but exhibit more “jerk” or
instantaneous change in acceleration, than better cam systems
• Geneva maintains good control of its load at all Times, since it is provided with locking ring
surfaces.
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23. DISADVANTAGES OF GENEVA MECHANISM
• The Geneva is not a versatile mechanism.
• The ratio of dwell period to motion is also established Once the no
of dwells per revolution has been selected.
• All Geneva acceleration curves start and end With finite acceleration
& deceleration.
•This means they produce jerk.
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24. APPLICATIONS OF GENEVA MECHANISM
• Stepper
• Mechanical Watches
• Plotters
• Cnc Machine
• Iron Ring Clock
• Modern film projectors may also use an electronically
controlled indexing mechanism or stepper motor, which allows for
fast-forwarding the film.
• Indexing tables in assembly lines, tool changers for CNC
machines and so on.
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25. CONCLUSION
 The parts namely Geneva wheel, rotator and baseplate were modeled using UNIGRAPHICS-NX
9.0 cad software and subsequently CNC coding were developed manually.
 The parts mentioned above were fabricated using conventional lathe, milling, and drilling
machines.
 Next stage of the process was carried out using CNC vertical machining centre to achieve the
near to finish dimensions and later the parts were finished using flat file and emery sheet.
 Finally the parts (Geneva wheel, Rotator) were assembled to the baseplate using fasteners
(bolt and nut) to complete the Geneva wheel mechanism.
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