Screw conveyor modeling machine in Solidworks?

Hello you are probably looking for 'equation' Feature of solidworks.
I can give you an easy example below:
Lets assume you want a cylinder which has an height of 3/4 th of its Diameter.
And you want to Change only the Diameter value and let the SW Change the rest.
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Step 1:
Create your first sketch of the circle with a defined Dimension for the circle, 20 mm in this case.
SW saves this value as 'D1@Sketch1' which you haven't probably notice till now. -
Step 2:
Under the Boss-extrude Feature, instead of giving a specific value you can put an equation (just like Excel sheet).
For our case it is 'D1@Sketch1*3/4'.
This equation will automativcally Change the Boss-extrude value everytime you Change the Diameter in step 1 -
Step 3:
If you want to Change the equation or any relationship between dimensions, just go under the 'Equation' tab in SW.
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Step 4:
You can Change, update or delete the relationship anytime you want from here.