Slotted Screw Drivers

Grinding Angle

Tip Thickness

Slotted Screwdrivers are sometimes called “flat head screwdrivers”, however purists argue that “flat head” is an improper terminology for this tool, noting that “flat head” refers to a type of screw shape.

A screwdriver can easily have the tip damaged, especially when the screwdriver is used as a prying tool. Fortunately, these can be re-ground. Using a Tormek makes this an easy task, and helps to ensure you do not soften the metal. If re-grinding on a bench grinder, care must be taken to ensure the metal is not overheated, weakening it.

Note: Some toolmakers will not harden the entire shaft of the screwdriver, only the tip and a bit up from there. If grinding off too much of the metal, the sharpener may find that the exposed metal is not hardened. Hardening that metal is difficult to do as most handles will be damaged in the process.

If the user wishes to retain the tool in a working state (e.g., for historical purposes), then the handle can be replaced after re-hardening the tool's steel. The Machinery's Handbook addresses hardening of metals, as does the American Machinists' Handbook.

General Guidelines
Type	α	Tip Thickness	Notes
1/16” Slotted	10°	0.015” - 0.020”
1/8” Slotted	10°	0.020” - 0.025”
5/32” Slotted	10°	0.025” - 0.030”
3/16” Slotted	10°	0.035” - 0.040”
1/4” Slotted	10°	0.040” - 0.045”
5/16” Slotted	10°	0.050” - 0.055”
3/8” Slotted	10°	0.060” - 0.065”
Jeweler's	25° - 35°	0.010” - 0.015”	Jeweler's Screwdriver Jeweler's screwdrivers like those seen in the picture to the right can easily have the tip damaged, especially when the tool is used (improperly) as a prying tool. Fortunately, these can be re-ground. The thicker angle for α provides for more strength at the tip. The tip is ground down to a minimal thickness to allow fitting the tool into the screw's slot.

Notes & Comments

Information regarding Grindstones

Flat	Good
Concave
Concave
Convex	Bad

Tip Shape

The best shape for the tip is slightly concave or flat.

Holding the Tool Whilst Grinding It

I found that it is best to hold the screwdriver in a jig which allows the sides to be easily ground opposite each other. The Tormek SVM-45 knife jig works well to hold Jeweler's tools by the knurled sides.

More Information

Books & Papers

• American Machinists’ Handbook, by Colvin and Stanley


• Machinery’s Handbook, published by Industrial Press


• Maintenance and Care of Hand Tools, 1945 Edition (PDF), from the U.S. War Department


• Use and Care of Hand Tools and Measuring Tools, 2004 Edition (PDF), from the U.S. Dept. of Defense


• Use and Care of Hand Tools and Measuring Tools, 2020 Edition (PDF), from the U.S. Dept. of Defense