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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. How often should we replace our retention knobs?

    Most all rotary toolholder manufacturers state that you should be replacing your pull studs at least every three years. However, if you are running multiple shifts, making lots of tool changes, making very heavy cuts with long reach or heavy cutting tools, you will probably need to replace your studs at least every year.

  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 and ISO30 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 angled surface 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. 

    Drawbar gripper marks on the outer knob diameter indicates dragging and that your gripper is not opening enough or you have selected the wrong retention knob.

  4. My retention knobs are showing dimple marks from the drawbar collet. Should I be concerned.

    There is nothing wrong with the metal balls or drawbar collet indenting or dimpling the retention knob head. In fact this is normal. Retention knobs are subject to extreme tension and compression loads. Because of these loads they must be hardened for toughness and should not be harder than 58rc. The drawbar collet and metal balls used in the drawbar collet are over 63rc, so it is normal for the harder metal balls to dimple the retention knob head.