Measuring tolerances in STL

[Horia]

Hello, I have a question regarding measuring tools for STLs. I am talking about premade STLs and not made by me.
I have been working with 123D Design, Netfabb and Meshmixer for 3 months but none of those programs have a solution for measuring tolerances. Tried to split the model in different axis (X,Y,Z) but my eye isn't that accurate so that I can correctly estimate the tolerance.
Edit: I tried with the ruler but no success. If there is a way to use that please tell me how.

Let's say I have a cylinder inside a hole and it has space so that the cylinder can move freely inside that hole.
How can I measure the space from the cylinder face to the inside of the hole?


Edit#2: Just done it with NetFabb Ruler.

Delete topic pls.