Crafting Precision: T.J. Davies Unleashes Custom-Made Retention Knobs for Optimal Machining Performance

T.J. Davies Co. Inc. specializes in crafting bespoke retention knobs, pull bolts, and various workholding components tailored for older or obsolete machinery. The customization options encompass all aspects of the knobs, including length, diameter, collar thickness, dimensions between collar and knob end, thread size, and more. Clients can specify additional features such as a coolant hole, taper style, and the inclusion of O rings. These tailor-made retention knobs are precisely sized to optimize the performance of the machine tool, spindle, or toolholder, enhancing toolholder efficiency, cutting tool lifespan, and prolonging the overall life of existing machine tool assets.

Crafted from American-made 8620 alloy steel, known for its high-tensile strength, the retention knobs from T.J. Davies are built to withstand robust centrifugal force, high load force, high feed rates, and challenging-to-machine materials. The in-house machining process involves single-point threading to imperial (Class 2A UNC) or metric (Class G6) standards. Following threading, each component undergoes heat treatment to achieve a hardness of 58-62 HRC and is treated with hot black oxide per military specifications for corrosion protection. Magnetic particle testing and pull tests, conducted at 2.5X the pulling force of the designed drawbar, ensure the reliability of each retention knob.

Utilizing 8620 alloy steel guarantees gradual hardening over time, avoiding brittleness often associated with the use of 9310 alloy steel. The single-point threading approach ensures balanced threads (lead-in/lead-out at 180 degrees), a challenging feat with thread rolling. Achieving full thread depth for each thread is another advantage of this method. Since all machining is executed with a single setup, exceptional concentricity is achieved.

Each component undergoes heat treatment to achieve a case depth of 0.020 to 0.030. The absence of carbide application to the coolant through hole prevents shrinkage. A standard core hardness of 40HRC is maintained. Precision finishes of 32 RMA micro or better, ISO grade 6N, are applied to all retention knob surfaces, not just mating surfaces. Stringent certifications are maintained for every step and batch to ensure traceability and uphold quality control standards.

T.J. Davies includes recommended torque guidelines with each retention knob and offers sockets designed for proper installation, available individually or as a complete set of four.

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