The angle which the axis of the spring wire makes with the horizontal line is known as helix angle.

low helix angle drill bits are used for machining hard materials

The helix angle of reamer is negative because to make the reamer more regid so that the reamer can withstand the vibration during reaming

maximum thrust is obtained.

The patterns and angle of the X suggested that DNA is a helix consisting of two strands that are a regular, consistent width apart. In a nutshell is was basically had a double helix structure.