A single-start screw has a lead of 1.5 mm. How far does it advance per full turn?

A single-start screw has a lead of 1.5 mm. How far does it advance per full turn?

• A. 0.5 mm
• B. 3.0 mm
• C. 1.5 mm
• D. 2.0 mm

Answer: (C)

The key idea is how far the screw moves along its axis with one full turn: that distance is the lead. For a single-start screw, the lead equals the pitch—the spacing between adjacent threads. So if the lead is 1.5 mm, each complete turn advances the nut (or the screw’s load) by 1.5 mm along the axis. The other numbers would correspond to different thread configurations (for example, more starts would increase the lead), but with a single-start screw the advance per turn is exactly 1.5 mm.

The key idea is how far the screw moves along its axis with one full turn: that distance is the lead. For a single-start screw, the lead equals the pitch—the spacing between adjacent threads. So if the lead is 1.5 mm, each complete turn advances the nut (or the screw’s load) by 1.5 mm along the axis. The other numbers would correspond to different thread configurations (for example, more starts would increase the lead), but with a single-start screw the advance per turn is exactly 1.5 mm.