Threaded Drill Bits #40

#40 Threaded Shank Cobalt Drill Bits for Aircraft Maintenance

#40 threaded shank cobalt drill bits are designed for precision drilling applications in aircraft maintenance, repair, and overhaul. These threaded-shank adapter drills feature a compact 1/4-28 threaded connection and are manufactured to NAS 965 Type D standards with a 135-degree split point.

The #40 drill size is commonly used for smaller fastener holes and precision drilling applications in aircraft sheet metal and components. The threaded shank design provides a secure connection to compatible threaded drill adapters while allowing the overall drilling setup to remain compact—an important advantage when working in the confined spaces frequently encountered during aircraft maintenance.

Cobalt construction provides excellent heat resistance and durability for demanding drilling applications. The 135-degree split point helps the drill start accurately and reduces walking when beginning a hole.

#40 Threaded Drill Bit Sizes and Lengths

BAC offers the #40 threaded drill in three overall lengths. Choosing the appropriate length allows technicians to balance access, reach, and control for the specific aircraft maintenance application.

Why Use a #40 Threaded Drill Bit?

Aircraft maintenance frequently requires drilling relatively small holes in areas where access is limited and drill control is important. A #40 threaded shank drill provides a compact drilling solution while maintaining the cutting characteristics needed for precision aircraft work.

• 1/4-28 threaded shank: Designed for use with compatible threaded drill adapters and drilling systems.
• #40 drill size: Provides a small-diameter drill size commonly used for precision fastener-hole and aircraft sheet-metal applications.
• Cobalt construction: Provides heat resistance and durability for demanding drilling operations.
• 135-degree split point: Helps the drill start accurately and reduces drill walking when beginning a hole.
• NAS 965 Type D: Manufactured to the dimensional and design requirements associated with NAS 965 Type D threaded shank adapter drills.
• Three length options: Long, short, and stub configurations allow technicians to select the appropriate drill for the available workspace.

#40 Threaded Drills for Aircraft Maintenance

#40 threaded drills are useful for precision drilling operations involving aircraft sheet metal, structural components, and fastener holes. Their small diameter makes them suitable for applications where a relatively small, accurately positioned hole is required.

The threaded-shank configuration can be particularly useful in confined aircraft maintenance areas. By using a compatible threaded adapter, technicians can create a compact drilling setup that provides access to areas where a conventional chuck and longer drill assembly may be difficult to position.

Choosing the Correct #40 Drill Length

The correct drill length depends primarily on access to the drilling location and the amount of reach required. Whenever practical, use a drill configuration that provides adequate access without unnecessary length.

The 9/16" stub provides the most compact configuration and is useful where workspace is restricted. The 1-1/4" short version provides additional reach while remaining relatively compact. The 2-1/8" long version provides the greatest reach when the drilling location requires additional length.

NAS 965 Type D Threaded Shank Drill

These #40 threaded shank adapter drills are manufactured to NAS 965 Type D standards and feature a 135-degree split point. The NAS specification is particularly relevant to aerospace tooling because it provides a recognized standard for threaded shank adapter drills used in aircraft maintenance applications.

Threaded Shank vs. Conventional Drill Bits

A conventional drill bit normally uses a straight shank held in a drill chuck or collet. A threaded shank drill instead connects to a compatible threaded adapter, creating a compact and secure connection between the drill and the tool.

This compact configuration can be advantageous when drilling aircraft components in restricted areas. The choice between a threaded and conventional drill should be based on the tooling available, access to the work area, and the requirements of the applicable aircraft maintenance procedure.

Aircraft Applications for #40 Drills

Depending on the aircraft and approved maintenance procedure, #40 threaded drills may be used for small fastener holes, aircraft sheet-metal work, component installation, repair operations, and other precision drilling applications.

Always verify the required hole diameter, drill size, drilling location, cutting parameters, and tooling against the applicable aircraft maintenance manual, structural repair manual, engineering instruction, or other approved procedure before drilling.

#40 Threaded Drill Bit Specifications