Dorian Tool 73310104080 Milling Machine Drawbar 7/16-20

Product Description

The DORIAN TOOL 73310104080 is a milling machine drawbar designed to secure tooling within the spindle of a vertical milling machine. The drawbar threads into the tool holder arbor and applies clamping force to keep the tooling seated during cutting operations. This unit has an overall length of 20.5 inches, a hex length of 2.5 inches, and a thread size of 7/16-20. The bar length measures 18 inches. Machining professionals and millwright technicians install and replace drawbars as part of routine spindle tooling maintenance.

This drawbar is compatible with the Bridgeport 1J Step Pulley milling machine, one of the most widely used vertical knee mills in job shops, toolrooms, and maintenance facilities. It is suited for shops running standard R8-taper tooling on that platform. Replacement is typically performed when the existing drawbar shows thread wear, bending, or cross-threading that compromises tool retention force during milling operations.

Key Features

• Overall length of 20.5 inches fits the Bridgeport 1J Step Pulley spindle stack height
• 7/16-20 thread size matches standard R8-arbor tooling thread specification
• 2.5-inch hex length provides adequate wrench engagement for proper torquing
• 18-inch bar length spans the quill and spindle housing as required
• OEM-style replacement geometry for direct drop-in fitment

Compatibility

Compatible with the Bridgeport 1J Step Pulley milling machine. Verify thread size and overall length against the existing drawbar before installation.

Installation Notes

Drawbar replacement is performed by qualified machinists or millwright technicians. Power down and lock out the machine at the main disconnect before accessing the spindle. Remove the existing drawbar by supporting the tool holder to prevent it from dropping, then thread in the replacement drawbar and snug with a wrench to the hex - do not over-tighten, as excessive force can damage spindle bearings or thread the arbor. Confirm full thread engagement before resuming cutting operations.