I keep encountering a somewhat annoying error when probing holes that have diameters slightly larger than the diameter of the probe tip of my Faro Arm. I can get around the error by selecting the "probe is larger than hole" option, but if the probe isn't larger than the hole, won't I be misrepresenting the center point? Has anyone encountered this problem or have any recommendations on how to get around it? (besides using a smaller ball probe, that's not always an option!) Thanks in advance!
I've seen that error before, but only when too few points have been probed. Is it possible that the probe is not recording a couple of the points due to instability or something?
Still seems to happen regardless of the number of points probed.
I think it is problem concerning the compensation...
Please check the displayed tip-diameter, perhaps start a new calibration anyway.
And if you use the orientation of the probe switch to 'compensation point' for compensating.
I think what "Firefly" means is to change the compensation method from compensation point (the default for all Faro devices) to Probe orientation, you do not need to place the probe at the center of your probed points to compensate.
The probe orientation compensation method means that you need to orient the shank of the probe so that it sticks out of the material. The compensation orientation is recorded on the first point only, all other points can be probed with any orientation.
Trying to probe a very "tight" hole (nearly the same diameter as your probe) is a nightmare when using a compensation point. Use the probe oreintation instead, in the "Device->Compensation method" section of the probing options.
QuoteI can get around the error by selecting the "probe is larger than hole" option, but if the probe isn't larger than the hole, won't I be misrepresenting the center point?
You're right, the "large probe" option should only be used if the probe is really larger than the hole. But maybe this an option for you? since it does not seem to be possible for you to use smaller probes, you might consider using a slightly larger instead?
The probe is larger than hole option should be used only if, physically, the probe sits on top of the hole.
The diameter of the circle is then calculated based on the probe's diameter and the distance to the constraining plane.
It is a very innacurate way of measuring a diameter. The center point of the circle is going to be OK, but the diameter may vary greatly depending on the bur on the edge of the hole.
Really, the best method to get accurate results is to change the compensation method to probe orientation instead of compensation point. Then you can get many points all around the inside of the hole. The arm is accurate enough that you do not have to have a great amount of movement for the precision to be good.