Accupro ER8J400000MSC Taper Drill Chuck Arbor JT4 R8

Product Description

The ACCUPRO ER8J400000MSC is a taper drill chuck arbor designed to connect a Jacobs Taper 4 (JT4) drill chuck to a milling machine or drill press spindle with an R8 shank taper. It serves as the mechanical interface between the chuck and the machine spindle, transmitting rotational force while maintaining precise concentricity. This arbor is used during drilling, boring, and reaming operations where a removable chuck is required. Machinists and tool and die technicians install this component when setting up drill chucks on Bridgeport-style and compatible R8-spindle milling machines. The part weighs 1.32 pounds and ships as a single-unit package.

This arbor is suited for machine shop environments requiring reliable chuck-to-spindle connections in light to medium-duty drilling and hole-making operations. The JT4 mount accepts standard Jacobs Taper 4 drill chucks, while the R8 shank seats directly into R8-collet-compatible spindles. It is appropriate for both production and maintenance machining tasks where fast chuck changes and repeatable runout are important.

Key Features

• JT4 Jacobs Taper mount accepts standard JT4 drill chucks
• R8 shank taper seats into R8-spindle milling machines and drill presses
• Tapered shank and mount design provides self-centering alignment for reduced runout
• Compact, single-piece construction with no loose components
• 1.32-pound weight suited for standard vertical milling spindle loads

Compatibility

Designed as an OEM-style replacement arbor for milling machines and drill presses equipped with an R8 spindle taper, accepting JT4 Jacobs Taper drill chucks.

Installation Notes

Installation is performed by qualified machinists or tool room technicians. Power down and lock out the machine spindle before seating or removing the arbor. Clean the R8 shank and spindle bore thoroughly before installation to prevent fretting and ensure full taper contact. Do not use the drawbar to force a misaligned taper into the spindle, as this can damage both the arbor and the spindle bore.