Capacitive TechNote LT03-0032
Copyright © 2012 Lion Precision. www.lionprecision.com
Summary
A method for reliably grounding masterballs.
Masterball Target Grounding:
Peak performance is achieved with capacitive sensors when the target is reliably
grounded. The rotor of a spindle may not be reliably connected to ground
because of separation between the rotor and stator caused bearing grease or a
nonconductive bearing technology such as ceramic or air.
To provide a reliable ground to a rotating shaft, the Lion Precision microfiber
ground brush assembly (P017-4350) can be used. The brush is installed on the
3- or 5-probe nest such that conductive microfibers remain in contact with the
rotating shaft while being measured.
The brush is positioned to contact the masterball shaft as shown below.
It is recommended that the system be installed and positioned before the brush is installed. This will prevent any accidental contact between the masterball and the grounding brush frame which could damage the masterball’s precision surface.
Installation is achieved with a single screw into existing threaded holes on the
probe nests. Different mounting holes are provided for mounting on the 3- and
5-probe nests (see below).
3-Probe Mount
5-Probe Mount
