How are v-blocks designed and why is this important? V-blocks are called v-blocks because their v-shaped design is central to how they function. A v-block is built with a v-shaped groove in the center of the tool where you place the cylindrical part with which you are working. This channel, or groove, is designed to be a 90-degree space located at a 45-degree rotation from both sides of the block. Positioned at evenly-spaced distances from each side as well as the base of the v-block, the groove is built to completely center and balance the cylindrical part you are drilling, milling, cutting, or inspecting. Cylindrical workpieces are difficult to work with in precision measurement tasks because of their shape. The precise design of the v-block is intended to solve this issue by making cylindrical parts stable during work.