Driven/Driving Dimensions

[jeph00]

Please see attached part. I want to change the diameter driving dimension, which in this case is 6.00", and have the other diameter dimensions change by the same amount. Problem I'm having is that when I do change 6" to say 5.98", the other dimensions do not change by the same amount, its either more or less. Why would this be and how can I fix it?

[vandyckaj · Accepted solution]

Hello,

So you have the right idea with making the model dynamic and updatable to save yourself the work in the long run. However I think you just went about it the wrong way and hopefully this will clear up your understanding. 

A driven dimension and driving a dimension are two very different things. A driven dimension as you had in your document, shown as (5.00) is a dimension that is being forced into being that number by some other constraints your model already has applied. For example. Making two lines perpendicular and then trying to dimension them with an angle. It will be 90 degrees but a driven dimension because it is being driven to 90 by the perpendicular constraint. 

Vs. Driving a dimension. That is best done with some variables. As I show how to do in this screencast. Hope this helps! 

[jeph00]

This is exactly what I've been trying to do. Very helpful screen cast, thanks for taking the time to demonstrate and explain. Makes a lot more sense now!