Jacobs 7342DN Drill Chuck Arbor JT6 Mount R8 Shank

Product Description

The JACOBS 7342DN is a taper drill chuck arbor designed to connect a drill chuck to a milling machine or drill press spindle. It features a JT6 Jacobs Taper mount on the chuck end and an R8 shank taper on the machine end, providing a secure, concentric interface between the chuck and spindle. The overall length is 5.33 inches, making it a standard-fit intermediate component. Machinists and tool-room technicians install this arbor as part of a complete chuck assembly. The tapered mount system eliminates threaded fasteners, relying on precision-ground mating tapers for rigidity and repeatable runout.

This arbor is used in manual milling machines and drill presses equipped with an R8 spindle taper, which is a common spindle standard on Bridgeport-style knee mills and similar vertical milling machines. It is installed as part of a two-piece chuck setup where the drill chuck body with a JT6 socket is pressed or seated onto the JT6 male taper of this arbor, and the R8 shank is inserted into the spindle. Typical applications include drilling, reaming, and light boring operations in job-shop, tool-room, and maintenance machining environments.

Key Features

• JT6 Jacobs Taper mount accepts drill chucks with a JT6 socket
• R8 shank taper fits R8-spindle milling machines and drill presses
• Overall length of 5.33 inches suits standard spindle-to-work clearances
• Tapered interface provides rigid, self-aligning chuck-to-spindle connection
• Weighs 1 pound for easy handling during tool changes

Compatibility

Designed for use with drill chucks that have a JT6 Jacobs Taper socket, installed in machine spindles with an R8 taper bore. Specific machine model compatibility depends on spindle taper confirmation prior to installation.

Installation Notes

This arbor is installed by a machinist or toolroom technician. Power down and lock out the machine spindle before installing or removing any chuck arbor. The R8 shank is inserted into the spindle bore and secured with the drawbar; confirm the drawbar thread engagement is correct for the R8 shank before applying torque. To seat the chuck onto the JT6 taper, press or drift the chuck body onto the arbor using a chuck-seating procedure rather than striking the chuck jaw body directly.