I tried using TolAnalyst to calculate RSS stackup on Gear Box Assembly given at Help Tutorials.
Do you know how Min and Max values are calculated both WC and RSS at backgraund?
RSS min max values are calculated iaw 1 sigma or 3 sigma?
I don't use TolAnalyst, but I would assume that it just does the square root of the sum of the squares for the values you put in for the tolerances. Whether those numbers mean 1 sigma or 3 sigma is up to the person who supplies them. Personally, I use 3 sigma values when I've got actual data.
For common linear stack-ups, RSS is just the common calculation that squares each tolerance divided by the standard deviation of 3, added together and then squared rooted (as noted by Jerry). For geometric tolerances, the RSS calculation also takes into account modifiers, such as MMC, and how much a feature is allowed to move within the assembly. This movement includes the how much a feature can vary within its tolerance range, and also includes the float between mating features, such as a stud in a bore.
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