Understanding Locating Devices for Cylindrical Jobs

In manufacturing and machining processes, it is crucial to accurately position and secure a workpiece. Devices used for this purpose are called locating devices. Different shapes of workpieces require different methods of locating. The question asks specifically about a device used to locate cylindrical jobs.

Let's examine the given options:

• Drill jigs: Drill jigs are primarily used to guide a drill bit to a precise location on a workpiece and ensure perpendicularity. While they might incorporate locating features, their main function is guiding the tool, not just holding a cylindrical job in position for various operations.
• V-blocks: V-blocks are precision metal blocks with a V-shaped groove. This groove is specifically designed to cradle and locate cylindrical workpieces. When a cylindrical part is placed in the V-groove, it makes contact along two lines, effectively centering and holding it securely. They are commonly used for inspecting, machining, or layout work on cylindrical parts.
• Angle plates: Angle plates are L-shaped castings used to hold workpieces at a right angle to a surface plate or machine table. They are versatile but do not specifically locate cylindrical jobs based on their cylindrical shape; they hold the job against a vertical face.
• Metal pins: Metal pins can be used as locating elements in jigs and fixtures, often fitting into holes or against surfaces. While pins can help locate parts, they are not a dedicated device designed explicitly for holding the body of a cylindrical job in the same way a V-block does by supporting its circumference.

Based on the function and design of these devices, the V-block is specifically designed to locate and hold cylindrical jobs accurately and securely due to its V-shaped groove that conforms to the cylindrical surface.

Therefore, the locating device used to locate cylindrical jobs is the V-block.