Basics of Coordinate Metrology
Unit 4:  Geometric Elements - Cylinder

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The next standard geometric element is the cylinder. A cylinder describes a cylindrical area in the direction of the cylinder axis of infinite extension without specification of the cylinder height (!). All points on the surface of the cylinder have the same vertical distance R from the cylinder axis. A cylinder has the following characteristics:
Extension: Radius R vertical to the cylinder axis, infinitely along the cylinder axis
Its direction is given by the cylinder axis

A cylinder is determined by at least five (probing) points (on the surface of the cylinder). These points are used to calculate the cylinder axis (described as a line through a point P (x, y, z) and a direction vector V (x, y, z). 

In practice the diameter (Ø) D is usually used instead of the radius R. It is twice the value of the radius (D = 2 R).

Tip: A good practical solution is a circular probing of the cylinder at various heights. Probing along a helical line is not recommended.

 

Important: The points used to calculate the cylinder must not be on a single circular or straight line.

      

Element:
Cylinder
Display:
Parameters:
point P (x, y, z), 
direction vector V (x, y, z)
radius R
Required minimum number of probing points:
5 probing points
Example using a part:
(Shaft, borehole)