Rhino - How to find the center axis of a helix

1. Use orient 2 points command to create a vertical (to cplane) helix.(use copy option and no scale option)
2. Use line pertfromcurve command (in top view) with planar mode on to create the blue lines
3. Use line command with INT osnap on to create the green line (axis)
4. Use orient 2 points command (copy= yes scale=no). Orient the green line using the red line (from both helix) endpoitns as reference.
5. Verification

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