Explore the essentials of machine tool spindle design, from types to trends, and select the right spindle with our comprehensive guide to enhancing productivity. A spindle is a rod or pin used for spinning thread, or a part that revolves or serves as an axis. Learn about different types of spindles, their uses, and related terms from various sources. spindle (third-person singular simple present spindles , present participle spindling, simple past and past participle spindled) (transitive) To make into a long tapered shape. Learn the key differences and similarities between shaft and spindle , two cylindrical components used in machinery and power transmission. Find out how they are designed, manufactured, and used in various industries and applications.