The tool used to create crisp, sharp scratches on the surface of material in preparation for machining is called a scribe. A scribing tool must have a sharp edge or point that presses into the surface of the metal displacing enough material to leave a visible scratch. It must be harder than the material being scribed, and it must be in a configuration that fits the operator’s hand.

In the figure above, the high speed steel (HSS) machinist scribe on the left has the tip broken off and requires a regrind to correct it. The scribe tip on the right is made from carbide and is capable of marking most materials.

Machinist scribes are commonly used in conjunction with layout or measuring tools such as rulers, squares, or protractors. The scribing process requires the point of the scribe to be carefully aligned against the guide, such as a ruler and workpiece. By applying pressure and dragging the scribe across the surface, a fine line is etched or scored into the material. This line serves as a guide for subsequent operations, such as cutting, drilling, or milling.

The scribe point is usually sharp and durable to ensure precise marking on different materials, including metals, plastics, or wood. Some scribes may feature replaceable tips, allowing for easy maintenance and prolonging the tool’s lifespan.

Machinist scribes are essential for accurate and meticulous work in machining, metal fabrication, woodworking, and other industries where precise marking and layout are crucial for achieving high-quality results.

Attributions

1. Figure 5.41: Selection of scribes by Damon Donner, for WA Open ProfTech, © SBCTC, CC BY 4.0
2. Figure 5.42: Scribe points by Damon Donner, for WA Open ProfTech, © SBCTC, CC BY 4.0