BELT TIGHTENER
Objective:
The student will construct a complete set of working drawings for the Belt Tightener including, detail
drawings, assembly drawing(s), Parts List and tolerance calculations.
Assignment:
Part I: Preliminary Sketches
Make a sketch on Graph Paper of each of the parts of the Belt Tightener. Show the necessary views and
add the required dimensions.
Part #1: Frame
 Sketch of the necessary views
 Sketch showing required dimensions
Part #2: Pulley
 Sketch of the necessary views
 Sketch showing required dimensions
Part #3: Bracket
 Sketch of the necessary views
 Sketch showing required dimensions
Part #4: Washer
 Sketch of the necessary views
 Sketch showing required dimensions
Part #5: Shaft
 Sketch of the necessary views
 Sketch showing required dimensions
Part #6: Pin
 Sketch of the necessary views
 Sketch showing required dimensions
Part #7: Bushing
 Sketch of the necessary views
 Sketch showing required dimensions
Part #8: #406 Woodruff Key
 Sketch of the necessary views
 Sketch showing required dimensions
Part #9: Hex Nut
 Sketch of the necessary views
 Sketch showing required dimensions
Assembly Drawing
 Sketch of the necessary views
 Parts List
Part II: Drawing Setup for CAD
Begin a new drawing and set the limits for size "C" drawing paper. Insert the border and title block (C-7)
into the drawing. Create the following layers:
Layer Name
Border
Construction
Object
Hidden
Center
Cuttingplane
Hatching
Dimensions
Description
Border and Title Block
Construction lines
Object lines
Hidden lines
Center lines
Cutting plane lines
Hatching lines
Dimensions, notes, text
Color
(student’s choice)
(student’s choice)
(student’s choice)
(student’s choice)
(student’s choice)
(student’s choice)
(student’s choice)
(student’s choice)
Linetype
Continuous
Continuous
Continuous
Hidden2
Center2
Phantom2
Continuous
Continuous
Lineweight
0.010
0.010
0.020
0.012
0.010
0.030
0.010
0.010
Create a new dimension style and set the dimensioning parameters as needed for mechanical style
dimensioning. Do not use AutoCAD’s default settings.
 Limits set for size "C" drawing paper
 The UNITS setting is to be
23.60 x 16.66
Decimal
 The precision setting for dimensioning is to be
.
.
0.00
.
BELT TIGHTENER
Part III: Tolerance Calculations
On engineering paper show the calculations for the following tolerances:
Part 7 in Part 2: Locational Interference Fit (ISO Symbol H7/p6) 26mm
Part 5 in Part 7: Free Running Fit (ISO Symbol H9/d9) 19mm
Part 5 in Part 1: Sliding Fit (ISO Symbol H7/g6) 22mm
Part 5 in Part 1: Sliding Fit (ISO Symbol H7/g6) 16mm
Part 6 in Part 1: Free Running Fit (ISO Symbol H9/d9) 16mm
Part 3 in Part 1: Sliding Fit (ISO Symbol H7/g6) 70mm
Use the Preferred Metric Hole Basis Clearance Fits-American National Standard tables in your textbook
To find the limit dimension values.
Calculate the required tolerances for the specified parts.
Set all tolerance dimensions to three decimal place accuracy (0.000).
Show all calculations on Engineering Paper.
Format for filling in the heading sections on the Engineering Paper:
Part IV: Grease Cup update
Replace the specification for the 1/8 American Standard Pipe Tap for Bowen Grease Cup (T-76-001) with a
10mm Grease Fitting/10mm Zerk Fitting (M10-1-AM) from SAE Products. Locate and print the
specifications from http://saeproducts.com and include this with the drawing project. Add this part to the
Parts List.
Part V: Complete the required drawings
Complete all of the required drawings following ANSI and ISO drafting standards. Drawings will include
detail drawings, assembly drawing(s), Parts List, revisions block, and general notes. Add identification
circles to the assembly drawing. Consult your drafting textbook for correct sizes. Add the titles of each
part below each detailed drawing.
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