7.3 Types of probes and sensor system
All CMMs have one or more probes and a method of moving them along three
orthogonal axes relative to the workpiece. Most the probes used currently are the ‘soft’ or touch
sensitive types. These types of probes use electronic mechanism to break the circuit when
contact between the probe and workpiece occurs.
Several types of touch probes are available and the type selected depends on the
workpiece material and dimension to be measured. All of these can be grouped into three types
as follows:
(a) Ball type probe
These are standard type probes used in CMMs and have various applications (Figure
7.6(a)).
(b) Tapered probe
These are used for determining the location and diameter of holes (Figure 7.6(b)).
(c) Cylindrical probe
The cylindrical probes are used to measure thin plates (Figure 7.6(c)).