Accupro 775344 End Mill Holder R8 Taper Shank

Product Description

The ACCUPRO 775344 is an R8 taper shank end mill holder designed for use in milling machines equipped with R8 spindles. It accepts a 3/8 inch bore and provides a 1.33 inch projection, positioning the cutting tool at the correct distance from the spindle face for standard milling operations. The holder features a drawbar thread size of 7/16-20, compatible with the drawbar found on most R8-spindle knee mills. Total indicator runout (TIR) is rated at 0.0002 inch, supporting accurate, repeatable cuts across a range of materials. Machinists and tool room technicians rely on this type of holder for secure cutter retention during face milling, slotting, and peripheral milling work.

This end mill holder is suited for manual knee mills and similar R8-spindle milling machines found in job shops, maintenance facilities, and tool rooms. It is used to hold straight-shank end mills in 3/8 inch shank diameter. The R8 taper interface is the standard found on Bridgeport-style and comparable knee mill platforms. No through-coolant capability is included, making this holder appropriate for dry or flood-coolant-from-outside setups rather than spindle-through coolant systems.

Key Features

• R8 taper shank for direct spindle mounting on standard knee mills
• 3/8 inch bore accommodates straight-shank end mills of that diameter
• 1.33 inch projection positions the cutter at the correct standoff from the spindle face
• TIR of 0.0002 inch for accurate, low-runout cutter seating
• 7/16-20 drawbar thread matches standard R8-spindle drawbar specifications
• No through-coolant passages, suitable for conventional flood or dry machining setups

Compatibility

Designed as an OEM-style replacement and standard tooling component for milling machines with R8 taper spindles accepting a 7/16-20 drawbar thread.

Installation Notes

Installation is performed by qualified machinists or tool room technicians. Before changing tooling, power down the milling machine and ensure the spindle has come to a complete stop. Secure the drawbar to the specified engagement using the machine manufacturer's procedure and verify that the setscrew is properly tightened against the end mill shank flat before beginning any cut. Inspect the taper bore and spindle taper for chips or debris prior to seating the holder.