Bison SET-TRU 3-jaw self-centering scroll chuck, model 7365-02, which has a 6-1/4" (160mm) diameter. This is a high-precision toolroom chuck designed for manual lathes where extremely tight concentricity is required.
Key Specifications
Accuracy: Features four micro-adjustment screws that allow you to dial in the workpiece to a repeatability of .0004" T.I.R. (Total Indicator Runout).
Construction: High-quality forged steel body, allowing for safe operation at higher spindle speeds compared to cast iron models.
Jaws: Equipped with 2-piece hard reversible jaws (American Standard Tongue and Groove), consisting of master jaws and reversible top jaws.
Mounting: Typically requires a specific SET-TRU back plate to utilize the fine-adjustment feature.
Use and Maintenance
Adjustment: To zero out runout, you slightly loosen the mounting bolts and use the four radial adjustment screws (visible on the side of the chuck) while checking with a dial indicator.
Included Accessories: Typically comes with a chuck key (the T-shaped tool in your photo) and mounting bolts.
Maintenance: Regular cleaning and lubrication with specialized chuck grease (e.g., Bison part #7-799-025) is recommended to maintain accuracy and longevity.