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Reading Drawings
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2. Why Have a Plan or Blueprint?
There are different types of plans or blueprints to allow the viewer different visual clues for producing the products.
Drawings are used to make the parts.
The drawing standards have been set for ease of understanding and producing the part.
There are different types of lines used to draw a blueprint or a plan.
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Machined Toy Top
1 dia.
2.75
1.50
.75
.25 dia.
The machined toy top is dimensioned in decimals. It shows two views: a front view and a right side view.
Ask the students what size piece of aluminum material will be needed to be cut to make their top.
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Types of Drawings
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5. Three View Drawing or Working Drawing3 1
1 1/2
2 1/2
1 3/4
The three view drawing or working drawing shows the object from three sides.
These views will show the shape of the object and location of any cutouts or holes.
The dimensions are usually added to this type of plan.
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Oblique Drawing
The oblique drawing is a pictorial drawing showing the shape of the object. The drawing is drawn as a front view, then the depth is projected from the corners at an angle. There are no dimensions or hidden lines on an oblique drawing.
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Isometric Drawing
The isometric drawing is drawn at a 30degree angle for the front and the side. This gives a 3D effect to the drawing. There are no dimensions or hidden lines on an isometric drawing.
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Exploded View Drawing
This drawing shows how parts in an assembly fit together.
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9. Sectional View Drawing
The sectional view is a drawing with a part removed or cut out to show the internal parts of the part.
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10. Sheet Metal Development Drawing
This drawing shows a box or other sheet metal project in a flat view. It allows the project to be laid out on metal, cut and folded in the finished product.
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Welding Plans .
The welding drawings describe how the weld joints are to be produced.
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Drawing a Plan
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Drawing a Plan
Only necessary views are drawn.
They show shape, location and size.
The front view shows the most detail.
Dimensions are in between views if possible.
Other views may be added for clarification.
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Drawing Projection
A glass box is unfolded showing all sides of the project.
Fig All Planes Are Revolved until they Coincide with the Front Plane
Fig. 256 Revolution of the Planes of Projections.
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Six Views of an Object
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16. Necessary Views of a Drawing
The three views in black are the necessary views: front, top, and right side.
The three views in red are mirror images of the black views and show the details as hidden lines.
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17. Dimensions on a Drawing3
Dimensioning each view makes the drawing too difficult to
understand.
The dimensions are placed on the drawing only once. 1
1 ½
1 ½
1 ½
1 ½ 1 1 1 2 2 1 1 3
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18. Correct Placement of Dimensions
1 ½ 3 1 2 1
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19. Types of Lines on a Blueprint
What are all the arrows pointing to?
What do dashed lines mean?
Have students attempt to answer the questions.
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20. Copyright © Texas Education Agency, 2012. All rights reserved.
Line
Symbol
Definition
Object
Solid black line showing the shape of an object
Hidden
Dashed line as dark as the object line shows shapes covered by other parts. For example, depth of a hole, etc.
Center
Line with a dash in the middle or a plus with lines radiating from it shows where the center is located.
Section
Line that has long and short sections with arrows pointed out shows the inside of a part by cutting out a section.
Fold
Line with 2 X’s show where to fold a sheet metal development.
Extension
A thin line extending from the edge to the dimension line indicates the dimension.
Dimension
Thin lines pointing to the extension lines show the measurement. + X X 2
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Plan Dimensions
Measurements are in inches or mm.
Dimensions have three parts: extension lines,
arrows and the number.
The largest measurements are on the outside of the set of dimensions.
Dimension arrows
6 1/4
Dimension number
Extension lines
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Examples of Plans
Fig Draw views with instruments; add missing lines. Layout 3D (Appendix I).
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Worm Saddle Plans 3
1 1/2
7/8
2 7/8
2 7/8
2 Dia.
7/8 DRILL
7 1/2
1/4
½ DRILL
2 HOLES
What is the length of the piece of metal this part is made from? 7 ½”
What is the thickness of the worm saddle? ¾ “
What size block on metal will it take machine the part? 7 1/2” X 3” X 3”
How many holes are drilled in the worm saddle? 3 (2) ½ drills and (1) 7/8 drill
Can you sketch a drawing of the worm saddle on graph paper? 3
3/4
2 1/2
2 1/2
WORM SADDLE
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24. Reading a Basic Drawing
1 1/2
1/2
2 1/2 4
1/2 DRILL
4 HOLES
1 R
3/4 R 1 2
What is the total length of the part?
What is the total height of the part?
Explain the dashed lines on the drawing?
The drawing is an adjuster base.
The total length is figured by taking the 4 inch measurement from the back of the block to the center of the 1” radius and adding the radius dimension 4” + 1” = 5”
The total height is done the same way the distance from the bottom of the part to the center of the ¾” radius and then adding then radius dimension 1 ½” + ¾” = 2 ¼”
The dashed lines are the edges of the 4 holes drilled in the part. The dashed lines show that the holes are located in the view but are hidden inside the part.
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25. Copyright © Texas Education Agency, 2012. All rights reserved.
Hammer Drawings
1/2” ROUND 3
1/4-20 THREADS 3/4” DEEP
HAMMER HANDLE
3/4 SQUARE
2 1/2
1 1/8
3/8
1/4-20 THREADS 3/4” DEEP 6
HAMMER HEAD
1/4” ROUND
1/4-20 THREADS x ¾ LENGTH BOTH ENDS
This slide shows the three pieces of the hammer.
The information on the three drawings are enough to make the parts.
HAMMER SHANK
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26. Exploded View of Hammer
The exploded view shows how to assemble the hammer.
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27. Sheet Metal Development
Cylinder
Prism
The graphic shows some of the different types of sheet metal development. The following slides will show how to read and draw simple sheet metal development drawings or plans.
Cone
Pyramid
Fig. 568 Development of Surfaces
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28. Sheet Metal Layout Drawings
The layout is a flat drawing with cut and fold lines drawn.
These lines are used to form (develop) the 3D shape.
Drawings have tabs, folds, and hems shown.
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Sheet Metal Box Plans
8 1/2 5
1/4 Hems
All Around 11 1
45° X
Hem
Fold
Hems fold over the edges so it is not sharp and the edge is strengthened.
Folds are marked to allow for bending the shape.
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30. Sheet Metal Layout Plans2 3 5
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31. Sheet Metal Layout Plans Or Development
10 1/2 2 1
ALL HEMS 1/4” 3
7 1/2 X
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