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Retention Knobs
  1. Do you make your own pull studs?

    Yes we do. All of our pull studs are made in the USA with high quality H-13 tool steel. We do not cut any corners when making pull studs. Pull studs are a very stressed part of your tool holding setup. Care must be taken when selection pull stud type and also who you get them from. Many companies do not properly heat treat pull studs or make them from cheaper materials.

  2. Do your retention knobs have rolled threads or single pointed threads?

    Our threads are single pointed on our cnc lathe while all other features are machined. Rolled threads have absolutely no benefit other than saving the manufacturer money. Sure rolled threads are stronger, but this has no valid point to pull studs. Thread strength is never an issue with pull studs when it comes to rigidity or failure. One of the problems with rolled threads is the fact that most of the time you lose concentricity when you roll the threads. Our threads are created when all other features are machined on the pull stud. This ensures perfect concentricity with all other diameters. Also when we create our threads we always make the front of the thread slightly larger in pitch diameter than the rear of the thread. This feature helps reduce and eliminate any tool holder bulge from over tightening the pull stud by keeping most pressure in the middle of the tool holder taper where it is stronger.

  3. What torque do you recommend tightening the retention knobs?

    We do not recommend any anti seize or lubricant during assembly, light oil is fine. Medium strength loctite may be used only if carefully applied after first thread in tool holder and do not apply loctite to the retention knob. This is to ensure loctite is located towards the strongest area of the tool holder and will not be able to bulge tool holder taper if it should happen to expand. Use sparingly.

    Here are the following pull stud / retention knob torque specs

    These values are for high torque, high strength, and normal models...


    BT30 pull stud / retention knob torque specs 20-25 ft lbs

    CAT40 or BT40 pull stud / retention knob torque specs 45-55 ft lbs

    CAT50 or BT50 pull stud / retention knob torque specs 75-90 ft lbs

    Pull stud / retention knob torque should be checked as part of your scheduled maintenance program.

    Drawbar gripper fingers and or ball marks may appear on retention knob head after several tool changes. This is perfectly normal.

    Gripper fingers and or balls are over 60rc, retention knobs are considerably softer so they do not crack and remain tough.