Probing small parts

I’d like to probe very small parts, is there a ratio of probe tip size to probe length that is recommended? I know that a smaller probe tip on a short stick needs more travel to trip and smaller probe tips get a lot more expensive. Ideally I would like a 1mm tip and at least an inch longer than stock probe. (When I probe the A-axis Chuck for center the probe body almost touches the Chuck.)
Anyone know about this?

@Dr_Harold_Jones ,

Great question. There’s no tip diameter to probe length ratio that I know of, but there is a stylus diameter to length ratio that styli manufactures follow: 1:10 - 1:30 depending on material (carbon fiber, tungsten carbide, ceramic). It’s easy to see why: long thin things bend, and stylus deflection is one of the primary sources of probing error.

Longer probe styli also magnify errors (whether they are mechanical, from vibration, or just from surface irregularity on the part you’re probing). A rule of thumb is that for every inch of increase in stylus length the you see about 0.0005" increase in error.

Practically speaking, if you are probing for A axis center, deflection will be an error that gets canceled in the center calculations. You could use a wet noodle as the probe stylus and as long as it deflects the same when you probe from the Y+ direction as it does from the Y- direction, your center will be unaffected :slight_smile:.

I hope that helps.