Brief description

A manual or powered tool used for turning screws. A typical screwdriver has a handle and a shaft, ending in a tip the user puts into the screw head before turning the handle.

Use / Function

• Primary use: Installing and removing screws.
• Secondary uses: Prying open lids, scraping (though not recommended).
• Scale: Manual, individual use.

Operating principle

The screwdriver amplifies the torque applied by the user’s hand.

• Torque: The larger diameter of the handle relative to the screw’s shaft provides a mechanical advantage, allowing the user to generate more torque than would be possible by turning the screw shaft directly.

How to create it

Minimum functional version

1. Shaft: Forge or grind a steel rod to flatten one end into a wedge shape (for slotted screws).
2. Handle: Carve a wooden handle with a central hole.
3. Assembly: Heat the non-tip end of the shaft (tang) and drive it into the wooden handle, or use epoxy/glue.

Technical level

• Basic: Requires basic metalworking to shape the tip and woodworking for the handle.

Materials needed

• Essential materials:
  • Steel: Hardened steel for the tip is crucial to prevent it from twisting or snapping under torque.
  • Wood/Plastic: For the handle, to provide grip and leverage.
• Tools:
  • File/Grinder: To shape the tip precisely.
  • Hammer: To seat the shaft in the handle.

Variants and improvements

• Phillips/Cross-head: Cruciform tip that self-centers but can cam out.
• Robertson (Square): High torque transfer, less cam-out.
• Torx: Star-shaped pattern for high torque transmission.
• Ratcheting: Allows continuous turning without removing the tip from the screw head.

Limits and risks

• Stripping: Using the wrong size or type of tip can damage the screw head (stripping it).
• Cam-out: The driver slipping out of the screw head under torque.
• Tip breakage: Hardened tips can be brittle; if used as a pry bar, they may snap.