Term :

Definition

Base Circle :

The diameter of the smallest circle that is tangent to the Cam-Profile.

Prime-Circle :

The diameter of the smallest circle that is tangent to the Pitch-Curve.

Cam Lift (STROKE) :

The difference between the Prime-Circle and the maximum radius of the Pitch-Curve.

Use a Measurement FB to measure the three dimensions of a Cam-Profile.

1.Click

2.Click Filters toolbar > Filter Points

Base-Circle

The Base-Circle is the minimum radius of the Cam-Profile.

When Add Measurement FB is active:

1.Click Kinematic FB toolbar > Measurement FB  (or Function-Block menu > Measurement)

2.Click the Contact-Point between the Follower-Roller and the Cam-Profile

3.Click a Point at the center of the Cam-Shaft

4.Click the graphics-area to place the Measurement FB

5.Cycle/Jog the model until the Measurement is a minimum

... you have found the radius of the Base-Circle

Prime-Circle

The Prime-Circle Radius = Base-Circle + Follower-Roller Radius

1.Add the radius of the Follower-Roller to the Base-Circle

or

1.Add a new Measurement FB to measure between the center of the Cam-Shaft and the center of the Follower-Roller

Cam-Lift (Stroke)

The difference between the minimum and maximum radii of the cam is the Cam-Lift (also called its Stroke).

1.Rotate/Jog the model until the Measurement is a minimum and note the dimension

2.Rotate/Jog the model until the Measurement is a maximum and note the dimension

Advantages of a small Cam.

A small cam:

•decreases required space

•decreases manufacturing cost - however, an extremely small cam can also increase manufacturing costs

•decreases inertia to help rapid starting and emergency stopping

•decreases out-of-balance force (if you do not balance the Cam)

•decreases Follower-Roller RPM - if you use the same roller

Disadvantages of a small Cam.

A small cam:

•decreases the flywheel effect - a flywheel helps to rotate the cam-shaft with a constant angular velocity.

•decrease the radius of curvature which will increase Hertzian Contact-Stress.