Bosch Hole Saw HTW138 1-3/8 Inch Edge Impact Tough Bi-Metal Integrated Arbor (8 TPI Hex Shank Sheet Metal Cutter Pilot Drill Component)

EDGE Impact Tough 1-3/8-Inch Integrated Bi-Metal Hole Saw with 8 TPI Sheet Metal Geometry, Safety Depth Stop, and Spring Plug Ejection

The Bosch HTW138 Edge 1-3/8 Inch Impact Tough Bi-Metal Hole Saw Integrated Arbor 8 TPI Sheet Metal Cutter Hex Shank delivers specialized structural sheet metal boring utility and exceptional rapid cutting efficiency across demanding electrical panel knockouts, commercial HVAC duct routing pathways, and automotive fabrication environments. Engineered as a heavy-duty one-piece assembly with an integrated arbor and a 5/32-inch center pilot bit, this high-performance layout tool interfaces natively with 1/4-inch hex impact drivers to provide up to 2X longer operational life cycles than standard alternative configurations. This professional contractor solution resolves walk-off hole deviations on curved sheet metal boundaries, accidental breakthrough damage to internal wires or structural members hidden behind the workspace, and core plug friction clear delays by combining a built-in safety depth stop ring with a percussive spring-loaded plug ejection matrix, an aggressive 8 TPI bi-metal tooth geometry, and torque-dampening metallurgical properties. Outfitted with an essential 1-3/8 inch cutting diameter path, a 2-3/4 inch total structural tool reach length, a slip-free 1/4-inch hex power connection shank, and application-specific maximum speed index charts ranging from 125 RPM to 375 RPM, this robust one-piece boring cutter optimizes subcontractor job site staging throughput during high-volume electrical conduit entry runs, metal housing adjustments, and architectural structural panel penetrations.

Best Used For:

• Electrical Enclosure Openings: Punching neat, concentric 1-3/8 inch knockout holes natively through structural mild steel breaker boxes and distribution panels for attaching conduit fittings.
• HVAC Duct Component Fitting: Slicing down thin galvanized sheet metal walls and aluminum ventilation ducts single-handedly on active worksites to run primary service loops.
• Safe Thin-Metal Perforations: Boring accurate pathways through exterior metal siding materials while ensuring the built-in collar blocks breakthrough drift into hidden insulation fields.

Key Performance & Safety Features

• Impact Tough Gearing: One-piece solid frame architecture isolates high-vibration rotational shock loads cleanly, fully dampening modern high-torque cordless impact gun pulse patterns.
• 8 TPI Bi-Metal Configuration: Optimized tooth profile maximizes shear velocity while reducing teeth stripping trends on sheet metal plates, ensuring balanced, burr-free entry borders.
• Built-In Collar Depth Stop: Rigid mechanical ridge stop stops forward tool breakthrough momentum automatically, shielding rear components from punch-through pilot contact.
• Spring-Loaded Mechanical Ejection: Compression wire spring continuously forces core disks out of the cup structure on exit, eliminating down-time scraping sequences.
• Integrated Mandrel Frame: Factory-set unified arbor and pilot drill alignment stops off-center assembly wobble, removing the operational hassle of mismatched accessories.

What's Included

• (1) Bosch EDGE™ Impact Tough™ 1-3/8-Inch Bi-Metal Sheet Metal Hole Saw
• (1) Integrated 1/4-Inch Hex Shank Connection Arbor Assembly
• (1) Integrated 5/32-Inch Center Twist Pilot Drill Bit
• (1) Pre-Installed Heavy-Duty Steel Plug Ejection Return Spring

Technical Specifications

Pro-Tip: When deploying this tool on hard steel enclosure paths, modulate the driver pressure flatly on the workpiece before pulling the trigger fully. Allowing the 8 TPI bi-metal layout to work smoothly at a steady, controlled rotational pace avoids teeth glazing patterns and dramatically lengthens active tool edge alignment lines.