How do you add accuracies for tools with different measurement devices?

#1
Hello,

If you want to measure something with a tool that uses more than 1 device and each one of them has it's own accuracy, how do you get the total accuracy?
Imagine you are measuring with a Laser tracker whith an accuracy of 0.05 and a reflector with an accuracy of 0.01. What the total accuracy would be?
 
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#2
There are different philosophies available here.
Some will combine them RSS, which would give you 0.051
Some will go with the more conservative algebraic addition, giving you 0.06.
Not much difference in this case, but if the accuracies get closer to each other it makes a bigger difference.
Let's say they were 0.05 and 0.04. then the RSS is 0.064 and the algebraic is 0.09

Personally I go conservative. Looking at my 0.05 and 0.04 example it is possible to get errors of -0.045 and +0.035, a total error of 0.080, and still have each term be in tolerance. The RSS combination of 0.064 would call the combined measurement out of tolerance.

The method you use will depend on what you are trying to accomplish.
 
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