For Faro Arm Users

[BigTank]

What is the maximum number of moves you have used for your equipment with repeatable results? Curious...

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Fitter, happier, more productive

 

[unclesyd]

I believe that the number of points depends on the software as I've never heard any complaints about the lack of data need for a particular set of measurements. I can't see the arm limiting as it just gets the data and sends it to separate processor.

I would contact FARO with your question. The last time I talked with them they were very forthcoming with information.

 

[BigTank]

Thanks for the tip, but I'm asking more about practicality as you come up against the limits of the arm's accuracy during use.

Right now, I'm using it to measure, in simplest terms, a 9'-0" cube volumetrically speaking that requires (4) moves. I've had trouble with repeatability in the past, but believe the problem has been solved through more careful setup and measurement procedure. I'm wondering if my movement philosophy might need changed for better accuracy from movement-to-movement.

It's just difficult for me to get my head to go from +/- 0.004" point-to-point accuracy to how accurate the arm can locate, say, an 11/16" dia. hole on the last move of the program. I'm not sure anyone can tell me definitively... That's a pretty complicated problem to solve geometrically and statistically.

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Fitter, happier, more productive

 

[geesamand]

I'm not sure of the details you're trying to work out, but anytime the words Faro and accuracy or repeatability come together I feel compelled to share my opinion.

My short opinion is that Faro accuracy varies significantly within the same volume. The real correlation between accuracy and arm movement is based on the angular movement of the arm encoders.

Therefore, if you are measuring features on opposite sides of an object you will see more error than if you measure 2 features on the same side of the object, because the arm has to contort and articulate much further in the first case. Take a plate with a single through-bore and measure the location of that bore from both sides to get a feel for this.

I have also studied the ASME standard for accuracy of arm style CMMs that Faro uses to test their arms and state accuracy performance. It's nowhere near as "tight" as the accuracy and IMHO it does not account for the real-world requirements of measuring actual features.

My personal opinion is that Faro equipment is fabulous if the portability and versatility outweigh accuracy requirements. If your accuracy requirement is anywhere near the stated accuracy of the unit, take great caution to verify that the Faro will provide the accuracy you need in your application.