Renishaw touch probe bits

[gerry maddenParticipant @gerrymadden53711]

I purchased some setting rings at an auction recently and the lot included a number of bits and pieces. One of these was a small box containing parts of a Renishaw TP20 touch probe from a CMM.

I did think I would attempt to re-sell it but I’m wondering if I can make a edge-finder out of it. There are two small brass contacts on the upper face of the unit, which look like electrical contracts, but these seem to be open-circuit regardless of whether the probe tip is touched or not. So its either broken OR I have no idea what I’m doing!

Can anyone advise me as to how this probe unit indicates to the CMM that its touched something? Reading the booklet in the box that the probe came in, the tip sensitive to 1/2 a micron deflection, so its a pretty clever device 🙂

Gerry

 

[SillyOldDufferModerator @sillyoldduffer]

Could be a strain gauge rather than resistive sensor?  The latter requires a voltage to be applied, and detects a current change on contact. Ohmmeter required.

A strain gauge produces a voltage on contact, so I guess no external power needed unless it contains an amplifier.  Voltmeter required.

Another guess: the resistance change and voltage produced are both tiny, requiring a sensitive multimeter or a scope to see what happens.  The electronics in a CMM are probably more sophisticated than a simple on-off switch detector.

Dave

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