What types of v-blocks are available for purchase? V-bocks are typically made out of either cast iron or steel and you will want to consider the types of materials you will be working with when choosing what material is best for your v-block design. When looking at v-blocks for purchase, you will notice two different grades, Grade A and Grade B. These are the two grades specified by IS: 2494-1964. Generally, v-blocks will have a bearing area of greater than or equal to 20%. The tolerance of a v-block is the maximum amount of distance separating two imaginary parallel places between the enclosed part. V-blocks are known to have symmetrization accuracy of 0.002 mm per 20 mm length in the vee groove and straightness accuracy is ±0.01 mm per 20 mm length. When shopping for a v-block, you will notice four faces: the flanks of the vees, the base end faces, the top, and the sides faces. V-blocks are usually sold in pairs matched in grade and size, allowing you to work with larger or longer cylindrical parts. Some v-blocks have two vees such that one is wider and deeper than the other. Another option when considering v-blocks are ones built with a 120-degree angle in order to check triangle effects or taps.