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Advanced Engineering Drawing
Mechanical Drawing
Constructing a Cam Profile
Uniform Motion
Objective:
This is a method describing the procedure to draw a radial plate cam with uniform motion.
Requirements:
Assume that a pointed follower is to rise 1 1/2" in a uniform motion in 180 degrees and fall 1 1/2" in the
same motion in 180 degrees. The rotation of the cam is counterclockwise. The diameter of the base circle
is 3".
Drawing the Cam Displacement Diagram:
1. Lay off the base line of the displacement diagram equal to the circumference of the base circle.
2.
Lay off the height of the displacement diagram equal to the maximum rise of the follower
(1 1/2"). Dimension this height.
3.
Divide the base line of the displacement diagram into twelve equal parts, each division
representing 30 degrees of cam rotation. Draw vertical lines through these points to complete
the displacement diagram. Label the divisions from zero degrees to 360 degrees.
4.
Draw a line from the base line at zero degrees to the maximum height of the displacement
diagram at the 180 degree line. This represents the rise of the cam motion. Draw a line from the
180 mark down to the base line at the 360 degree line. This represents the fall of the cam motion.
5.
The displacement diagram describing the cam motion is completed. Add a title to the
displacement diagram to complete the drawing.
Constructing the Cam Profile:
1. Construct the base circle including centerlines.
2.
Draw radial line spaced every 30 degrees. Label these lines in a clockwise direction. The
rotation direction is given in the problem. The labels should correspond to the degree numbers
on the displacement diagram.
3.
Transfer the distances for each degree interval from the displacement diagram to the radial lines.
The distances are measured from the base line of the displacement diagram to the graphed cam
motion line.
4.
Draw a smooth curve through the intersection on the radial lines to complete the cam profile.
Finished Cam Drawing:
1. Darken in the cam profile. Show the radial lines as dimension lines for dimensioning a radius
and then show the dimension of the distance from the center of the base circle to the cam
profile and the degree number. Draw the shaft and the key and add the dimensions.
2.
Draw and dimension the cam follower. Be sure to show the minimum and maximum position of
the follower. Dimension this distance.
3.
Indicate the rotation direction.
4.
Draw the side view of the complete cam, shaft, key, and follower.
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