Drawbar Retention

Drawbar force is one of the most critical—yet often overlooked—factors in spindle performance. When retention force drops out of spec, it doesn’t just affect tool holding—it can lead to taper damage, broken retention knobs, and costly spindle repairs. In this short video, Moe St. Onge of SPS Spindle walks through how drawbar systems actually work inside a machine tool spindle. Using a cutaway 40-taper spindle, he demonstrates the role of Belleville washers, the gripper assembly, and how proper tension is maintained. You’ll also see how to properly check drawbar force using a gauge system, why regular testing is essential, and how insufficient retention force can lead to serious issues—including damaged tapers, broken components, and costly spindle repairs. Most importantly, this video highlights how a failing drawbar doesn’t just affect the drawbar itself—it can compromise the entire spindle system. If you’re running a high-performance spindle, this is a must-watch. Regular drawbar force verification can prevent unexpected downtime, protect your spindle investment, and ensure consistent machining accuracy. For more information on spindle repair, drawbar retention, or force testing, visit our website or reach out to the SPS Spindle team.