The driver gear and the driven gear dimensions as below and they are to be metric with the following specifications: Driver Driven Number of teeth 18 19 Pitch diameter 73 mm 78.8 mm Outside diameter...

The driver gear and the driven gear dimensions as below and they are to be
metric with the following specifications:
Driver Driven
Number of teeth 18 19
Pitch diameter 73 mm 78.8 mm
Outside diameter 81 mm 87 mm
Pressure angle 20 20
Figure 1. Gears dimensions.
Drive from the motor to the roller is by V-belts running between two pulleys. Each
pulley is to be keyed to its respective shaft. The electric motor, refer to figure 2
for the basic dimensions, runs at a constant 1440 rpm but the roller must operate
at 900 rpm ± 10 rpm. Use these information to find the second pulley diameter.
The distance between the centre motor and the centre of the roller can vary
etween 560 to 600 mm.
Figure 2. Electric moto

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General introduction
MEC2304 – Solid modelling 1
Assignment 2

Solid modelling project

Due date: 21 October 2019
Value: 750 of the 1000 marks for this course

Background
A grain milling machine is a machine that
eaks grains into smaller pieces by grinding,
crushing, or cutting. The grinding process occurs through mechanical forces that
eak up the
structure by overcoming the interior bonding forces. After the grinding the state of the grain is
changed: the grain size, the grain size disposition and the grain shape. In this project, a two-
oller mills have been adopted. These type of grinders are the simplest variety, in which the
material is crushed between two rollers before it continues on to its final destination. The
spacing between these two rollers can be adjusted by the operator. Thinner spacing usually
leads to that material being crushed into smaller pieces.
This is a reverse engineering project as we have the machine and we need to generate the solid
model, the engineering detail drawings and to justify the functionality of each component. The
individual assignment activities of the project have been divided on a weekly bases to help you
master different modelling techniques and use more advanced functions of the CREO software.
Cu
ently, there are two shafts: driver and driven one. The driver shaft is a bit longer and it has
a pulley connected with a belt to a motor. The driver shaft also has a spur gear with 18 teeth
while the driven shaft gear has 19 teeth. The milling cylinders are identical on both shafts and
the gap between the two rollers is controlled by a mechanism pushing the driven shaft in and
out of the main body. This gap should be less than 3mm and bigger than 0mm.
The driver shaft has a diameter of 25mm. Force calculations predict this to be an appropriate
dimensions to allow good life span and use of the machine. However, if the actual forces differ
substantially from the calculated values then this diameters will have to change. The model you
create should facilitate this design consideration e.g. subsequent editing of the driver shaft
diameters should automatically update the dimensions of the roller hole. The co
esponding
features of the gear; pulley; bearings and other parts should also be automatically updated. It is
anticipated the 25mm driver shaft section will not exceed 28 mm.

2 MEC2304 – Solid modelling
The Project
Your task is to complete the overall design and the design of the various milling machine
components from the diagrams and images provided. More specifically you are required to:
1. Create parametric feature-based solid models for all the components either shown or listed
in the following pages. Part that are listed and may have been included in the following
pages are: belt, two pulleys, two gears, two different type of bearings (outside details only),
motor (general outside shape only), and the supporting structure for the machine.
2. Create an assembly model showing all parts in their working position.
3. Set up a parametric relationship equation between the Driver shaft and All the parts
connected to it, to satisfy the design requirement as outlined in the Background information
above.
4. Produce an engineering assembly drawing of the milling machine as configured in 2 above.
In addition to the orthographic views the drawing should also include a 3D view, title block,
parts lists, and other information generally shown in assembly drawings.
5. Produce fully dimensioned engineering detail drawings for the parts listed below:
 Main frame
 Steel hopper
 End plate
 Driven pulley
 Driver shaft
 Inner plate 1
 Outlet funnel
 Supporting structure
Specify appropriate surface finish requirements, general tolerances, and other information
normally shown in a detail drawing. Also include a 3D view of the part in addition to the
orthographic views or view.
6. Nominate and justify suitable fits and tolerances on a separate A4 sheet for the following
mating parts / features:
 Driver and driven shafts and those components connected to the shafts such as: gears,
ollers, bearings and pulley if the shaft connected to it.
The basic size and tolerance sizes for each fit should be included on the sheet. The
tolerance sizes should also appear in the detail drawings.
MEC2304 – Solid modelling 3
Guidance on the Project
The diagrams provided show limited details and in many cases the dimensioning of the details
is incomplete or missing (minimal dimensions provided). Therefore, you will be expected to
combine some research with sound practical judgement to obtain all the missing information
necessary to complete the design.
Before commencing this assignment you should think about the function of each feature and
each part and how the individual components might be made. Also consider the physical
assembly process i.e. how the parts actually fit together, the order in which the components
might be put together and the use of sub-assemblies. Your model creation process should reflect
this wherever possible. Some guidance is given in the instructions for the Roller Bracket
exercise you completed as part of assignment 1. I would like to suggest you hand sketch each
part before you model them.
What you need to submit:
Your assignment is to be submitted online through USQ StudyDesk in a compressed (zipped)
folder. Do not submit the files individually.
In the zipped folder include:
• Part ‘.prt’ files and assembly ‘.asm’ files of all the Creo5.0 models*
• ‘.pdf ‘ files for all the working drawings listed in 4 and 5 above – i.e. you will need to
‘save as’ or’ export’ the Creo5.0 drawings (.drw) to .pdf before submitting. Do not
submit Creo5.0 .drw files.
• A ‘.pdf’ electronic copy of an A4 sheet or sheets (created from a word document)
with:
 A listing of the file names you used for each part and each assembly.
 Fits and tolerance justifications as requested in 6 above.
 Instructions on how to test the parametric relationship between the Shaft and the
connected components.
Check that your files open co
ectly from the zipped folder before submitting your assignment.
It is very important that you do this as a marks penalty will apply if the files cannot be easily
accessed by the markers.
Marking this assignment
The following sample marking sheet has been included to indicate the criterion to be assessed
and the relative marking for each criteria.
4 MEC2304 – Solid modelling
MEC2304 Assignment 2 – marking sheet
Student name: _______________________________
Marker: ______________________________ XXXXXXXXXXTotal mark / 750
Models
Criterion Your mark Out of
1. completeness – all parts modelled and all features included 100
2. accuracy of parts and assembly 150
3. presentation / creation of computer models, part and / or
assembly relations
200
total 450
Assembly drawing

Criterion Your mark Out of
1. completeness – all parts shown and clearly identified; title
lock / parts lists
50
2. presentation / clarity – view selection and layout 50
total 100
Detail drawings

Criterion Your mark Out of
1. completeness – all parts drawn and submitted; title block /
notes
60
2. presentation / clarity – view selection and layout 60
3. accuracy – dimensioning / tolerances / surfaces finishes 80
total 200
Marker’s feedback and comments:
MEC2304 – Solid modelling 5
Figure 1: Mini milling machine.
6 MEC2304 – Solid modelling
Week 1: you should complete all the following parts, partial of the assembly shown
elow.
Figure 2: End plate assembly details
Figure 3: Plate and Handle details
MEC2304 – Solid modelling 7
Figure 4: Guide bushes.

Figure 5: End Plate details
8 MEC2304 – Solid modelling

Figure 6: Driver shaft
The driven shaft is 230 mm and the two ends is 20mm in diameter for length of 75 from
each end and the middle part of the shaft is 25mm diameter.
9
MEC2304 – Solid modelling
Figure 7: Roller details (it has 84 triangular teeth and the outside diameter is 75.5mm),
the tooth depth is 2mm.
Figure 8: Driven pulley
10
Figure 9: Gate plate
Figure 10: cover plate details

11
Week 2: You should complete the frame (This is partial of the frame assembly)
The main frame is made from 50×50×6.5 mm steel angle.
Figure 11: Main frame details 1.
12
Figure 12: Steel hopper made from 1.6mm steel sheet and the base is 4.5mm.
13
Figure 13: Steel hopper made from 1.6mm steel sheet and the