Pencils and Leads
Two types of pencils are used in drafting: wooden and mechanical. The mechanical type is actually a lead holder and may be used with leads of different hardness or softness. There are a number of different drawing media and types of reproduction and they require different kinds of pencil leads. Pencil manufacturers market three types that are used to prepare engineering
drawings; graphite, plastic, and plastic-graphite. Graphite lead is the conventional type we have used for years. It is made of graphite, clay, and resin and it is available in a variety of grades or hardness. Drafting pencils are graded according to the
relative hardness. A soft pencil is designated by the letter B, a hard pencil by the letter H. Figure 2-1 shows 17 common grades of drafting pencils from 6B (the softest and the one that produces the thickest line) to 9H (the hardest and one that produces a thin, gray line).
You will notice that the diameters of the lead vary. This feature adds strength to the softer grades. As a result, softer grades are thicker and produce broader lines, while harder grades are smaller and produce thinner lines. Unfortunately, manufacturers of pencils have not established uniformity in grades. Hence, a 3H may vary in hardness from company to company. With experience and preference, you may select the trade name and grade of pencil that suits your needs.
Two types of pencils are used in drafting: wooden and mechanical. The mechanical type is actually a lead holder and may be used with leads of different hardness or softness. There are a number of different drawing media and types of reproduction and they require different kinds of pencil leads. Pencil manufacturers market three types that are used to prepare engineering
drawings; graphite, plastic, and plastic-graphite. Graphite lead is the conventional type we have used for years. It is made of graphite, clay, and resin and it is available in a variety of grades or hardness. Drafting pencils are graded according to the
relative hardness. A soft pencil is designated by the letter B, a hard pencil by the letter H. Figure 2-1 shows 17 common grades of drafting pencils from 6B (the softest and the one that produces the thickest line) to 9H (the hardest and one that produces a thin, gray line).
You will notice that the diameters of the lead vary. This feature adds strength to the softer grades. As a result, softer grades are thicker and produce broader lines, while harder grades are smaller and produce thinner lines. Unfortunately, manufacturers of pencils have not established uniformity in grades. Hence, a 3H may vary in hardness from company to company. With experience and preference, you may select the trade name and grade of pencil that suits your needs.
