MECHANICAL DRAWING
and
Standard Operating Procedure
Procedure in Setting up Drawing
tools, Materials and Equipment
•Before starting the drawing activity:
•Select the tools, materials and equipment which are needed
in the assigned task.
•Properly set up the required tools and materials in a place which is
convenient for you to move and execute your work.
•Clean the table and tools, see to it that these are free from the dust
and other elements that would cause damage to your work.
•Wash your hand with clean water.
•Activity proper:
•Perform the activity by following the standard operating procedure
per job requirement.
•Properly manipulate all the tools and equipment that are used in the
activity.
•In case of meeting an errors or mistakes along the way of activity
( for instance misprinting of lines, letters, and other forms of mistakes)
use appropriate eraser for a particular mistakes.
•After the activity:
• Submit your output to your teacher for checking
•Check all the tools and materials to ensure that nothing has lost.
•Return the tools and materials to the assigned tool keeper for safekeeping.
•Clean your work station before leaving.
Alphabet of Lines
Lines in technical drawing are represented as follows:
• According to weight
•Thick
•Medium
•Thin
•According to construction
•Continues line
•Broken and dashed line
•Combination of continues and broken/dashed line
•According to meaning or use
• Border lines are generally the heaviest or the darkest lines in a drawing. The border surrounds a drawing and is usually rectangular in shape. It makes the onlooker feels as if the parts of the drawing are combined into a single unified graphic representation.
• Visible lines this is used to show the outlines and corners that can be seen when the object is viewed. It is often called as the object lines.
• Hidden lines this is used to show the edges that are not normally seen when the object is viewed.
• Dimension lines this is a line terminated by arrowheads at each of its end, it is used to indicate the direction and extent of measurements. Along this line is a numerical value indicating the units of measurements.
• Extension lines this is lines that extends from a point in the drawing to which the dimension refers and meets the dimension line at the right angle.
20m
m2
0m
m20
mm
20mm20mm20mm
60m
m
• Center line this is used to indicate the center of a circle or arc, or to indicate the axis of an object with circular features.
•Leader Line – a thin solid line leading from a dimension value or a note to thepart on the drawing to which the note applies. An arrowhead is used to pointthe leader, but never on the note end. The end note of the leader should endwith a short horizontal bar at the mid-height of the lettering and should runeither to the beginning or end of the note.
Leader Line
• Cutting plane lines this lines are used to indicate an imaginary cut through an object along the line. It is made with long heavy dashes alternating with two short dashes.
• Section lines this are light lines used in making sectional views. They are spaced evenly to make a shaded effect.
THEORIES AND PRINCIPLES OF ORTHOGRAPHIC
PROJECTIONThe term orthographic came from the Greek word orthos and
graphos which means straight line drawing.
Planes of Projection
•Frontal Plane – this shows the shape of an object when viewed from the front.
This is known as the Front View of the object.
•Horizontal Plane – this give the appearance
of the object as if viewed directly from above.
It shows the distance from the front to the rear.
This is known as the Top View of an object.
•Profile Plane – this shows the shape of the
object when viewed from the side. The distance
from bottom to top and front to rear also appears.
It is known as the Side View of an object.
When opening the planes that forms a box or is sometimes called imaginary
box, the six views of the object are represented on the following positions as
shown below.
1. Top View
2. Front View
3. Bottom View
4. Rear View
5. Left Side View
6. Right Side View
FRONT VIEW: Height and Width
TOP VIEW: Width and Depth
RIGHT VIEW: Depth and Height
Principles of Orthographic Drawing
1. The front view and top view are always drawn in line vertically.
Align views with each other (features project from one view to the next)
2. The front and the right side view are always drawn in line horizontally.
8. A line projected perpendicularly to the plane of projection, its projection onthe plane will be a line.
13. The front of the object in the side view faces the front view.
3. The height of the front view is the same as height of the right side view.
4. The depth of the top view is the same as the depth of the side view.
6. A view taken from above is a top view and must be drawn above the front view.
7. A view taken from below is a bottom view and must appear below the front view.
9. A line when projected parallel to the plane of projection, its projection will be a line.
10. An inclined line projected to the plane of projection, its projection on the plane will be foreshortened.
11. A view from the right, is a right-side view and must be drawn left of the front view.
12. The front view of the object in the top view faces the front view.
Plan View or Top ViewThis can be little more difficult to visualize because you have to imagine yourself moving over the top of the object and looking vertically downward. The left-hand and right-hand illustration shows how the plan is placed above the front. Again, sketch the light vertical construction lines to locate the plan in its proper position. Draw these upward from each corner of the front view.
Front ViewConcentrate on the front view. If you look at it correctly the effect
will be seen below at the left, while at the right illustration shows whatyou will actually see. Notice that in the left-hand drawing, you can only seethe dark-inked front “face” of the object. Notice also that you cannot seeany of the other sides of the object. This is because all those sides are“going away” from you in your line of sight and are simply not visible fromyour view point. They are still there, of course, but are hidden behind theouter edges of the first face.
Right-Side View
Right-side view should be drawn at the right side of front view. Imagine movingaround the object to look directly at its right side. How you see it is shown below-left andwhat you see is shown below-right. Again the faces you actually see are heavily outlined.
Procedure in Constructing Orthographic Views
1. Analyze the given object.
2. Draw the proper construction line where the three regular
view of the orthographic projection will be designated.
FRONT VIEW SIDE VIEW
TOP VIEW
3. Start focusing at the frontal plane of the object to obtain the
necessary details of the front view.
• Consider the height and length of the
object in constructing the front view.
Draw the height details using construction
lines.
4.Draw the length details of front view.
• Extend the construction lines to the
position of the plan considering that the
front view and the plan share the same
length as stated in the principles of
orthographic drawing.
5. Draw the object lines base on the intersection of the construction lines
of step 3 and step 4.
6. Provide a distance of not less than 20mm on top of the front view to start the construction of the plan. Draw the depth details of the object since the length details are already in place. Use construction lines in doing this step
7. Draw the object lines base on the intersected of the construction
lines that corresponds to the details of the object.
8. Provide a 45° angle line that extends from the edge of the front view
towards the side of the plan.
•The 45°angle line will serve as a pivotal
point of the lines that have intersected it
coming from the depth details of the plan.
Lines that are intersected will be projected
towards the Position of the right side view
which will provide the same depth of the
right side view. Use construction lines in
doing this step.
9. Draw the object lines base on the intersected of the construction
lines that corresponds to the details of the object.
10. Provide the necessary labels,
and dimensions of each of the views.
20m
m2
0m
m20
mm
20mm20mm20mm
60m
m
Drawing Exercises: Base on the given drawings, construct thethree principal views following the principles in constructing orthographic drawing.Utilize the proper type of lines in accordance with its use.
