# Equation driven conical spring not rebuilding properly in Solidworks 2019

I'm trying to make an equation driven conical spiral, you can download the file here. I know that I can use the spiral tool to achieve this but there are reasons why I want to do it like this. I have five global variables that control the characteristics of the spring: the initial radius ri, the final radius rf, height H, number of coils nc, and diameter of wire d (it's a square wire so the diameter is the width/height of the square). The equations for generating the coil are:

x=("ri"-t*(("rf"-"ri")/"H"))*cos(t*((2*pi*"nc")/"H"))

y=("ri"-t*(("rf"-"ri")/"H"))*sin(t*((2*pi*"nc")/"H"))

z=t


with limits from t=0 to t=H. The problem is that when I change the variables, the spring does not rebuild, even when I use Ctrl+Q several times. I have no idea why this is. I have another small coil above the spring which I'm going to use to make an end coil and it seems to update ok but the main coil doesn't. Any help would be appreciated.

• Why wouldn’t global variables work with the standard helix method? Dec 13 '19 at 8:48
• Hi @enea19 - I downloaded your file, edited some of the global variables, and it seemed to rebuild just fine? It has to be Ctrl+Q rather than Ctrl+B, but I can't replicate your problem. Dec 13 '19 at 11:22