GearPro Involute Probe Diameter

[[an...]]

Hi, first post 🙂
I am looking for suggestions for determining the optimum probe tip diameter for measuring gears. Is the largest diameter that will fit in the tooth better than a very small diameter tip?
Thanks.

[[Ma...]]

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The answer depends somewhat on what characteristics you are trying to measure on the gear teeth. If you are trying to measure pitch using 2-flank measurement you will need a probe sized correctly to contact somewhere near the middle of the tooth profile. If you are measuring the involute profile of the tooth you will need to use a probe small enough to explore the full active profile of the tooth without interference in the root area.

[[an...]]

Thanks Mark,
For a 2 flank measurement, as long as the stylus diameter isn't too large to actually fit between the teeth, is there a meaningful difference in results due to a smaller vs. larger stylus diameter choice?
Thanks again.

[[Ma...]]

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For best correlation to manual measurement, the ideal stylus diameter would be the same as the specified ball diameter for tooth size measurement. Using standard stylii, this is usually not possible. Differences can be caused by inaccuracies of the tooth surface from nominal. Generally speaking, these differences are reduced as the geometric errors of the gear become smaller. Low accuracy or heavily modified profiles would cause larger differences than high accuracy unmodified profiles.

[[Wo...]]

The best probe diameter for single probing is Modul / 2.
For the measurement in double flank probing the probe is available from Drawing: MdK Ballsize
In the case of evaluation "shop floor evaluation" ( MdK in double flank tolerance )the probe must be Ballsize.

In measuring pitch and runout with single flank probing the probing diameter to measure it, you can calculate the diameter in tolerance runout by inputting the Mdk Ballsize and get the contact diameter. This diameter you can copy to the diameter for pitch measurement. This is avoiding the differences between double flank measurement and single flank measurement.