The pencil shaft (wooden shell) is made flat to prevent the pencil from rolling around. The pen lead is made flat to fit the wooden shell.
The shapes of pencils include cylindrical, right prism, elliptical cylinder, etc., and the cross-sections are circular, regular polygon, elliptical, etc. The use of pencils was once much more common than it is now. The original pencils were Cylindrical shape, it often rolls around on the table, and often falls under the table, breaking the pen tip. Therefore, someone applied for a patent for making the pencil into a prismatic shape. Because the output of pencils was very large at that time, this small patent was It brought a lot of patent royalties to the inventor and made a lot of money.
In fact, the small carpentry pencil also contains a lot of industrial design considerations.
Pencils include many types depending on their uses and users. Woodworkers use pencils mainly for drawing lines. They throw them away after use and do not handle them lightly (a waste of time). Therefore, in order not to cry It rolls randomly and is generally not made into a cylindrical shape or a prismatic shape - because it is thrown away after use. If it is a prismatic shape, it will still roll and jump. Therefore, pencils used for woodworking The handles are made into a relatively flat, strong and elliptical cylinder---after being put down after use, they will neither continue to roll nor jump due to restricted movement, but will roll once or twice or shake a few times before returning to normal. Calm. Moreover, most carpentry pencils are made in bright red, so that they can be easily found at a glance the next time they are used, instead of having to search for them among a bunch of tools and items.