Hello all, I am new to Solid works and am struggling to figure something out.

How do I create global variables from part dimensions. Currently I am trying to figure out how to get a bend radius from a sheet metal part into an assembly to drive other things including an assembly plane position. If I copy the variable name to the assembly equations, it does not understand to link it, I assume because the dimensions name is from the part not the assembly. How do I overcome this issue?