Bosch T3923SC 4-inch SDS-plus SpeedCore thin wall core bit extension highlighting the threaded connection end and the heavy-duty steel shank.
Diagram showing the assembly of the Bosch SDS-plus core bit extension system, featuring the mandrel assembly, pilot bit, and high-grade tungsten carbide core bit with an ejector hole.
Graphic displaying the ideal materials for the Bosch SpeedCore thin wall core bit extension, including masonry, brick, block, and concrete.
Angled view of a Bosch thin wall core bit with a pilot bit installed, attached to the 4-inch SDS-plus core bit extension for deep concrete drilling.
Side profile of the Bosch core bit connected to the T3923SC 4-inch SDS-plus extension, demonstrating the seamless two-piece assembly ready for heavy-duty drilling.
Close-up of a worker using a Bosch hammer drill equipped with a masonry bit to precisely drill a hole through a metal electrical box mounted on a concrete block wall.
Worker wearing heavy-duty gloves operating a Bosch hammer drill with a masonry bit to secure a metal electrical junction box to a concrete block wall.
Bosch T3923SC 4-inch SDS-plus SpeedCore thin wall core bit extension highlighting the threaded connection end and the heavy-duty steel shank.
Diagram showing the assembly of the Bosch SDS-plus core bit extension system, featuring the mandrel assembly, pilot bit, and high-grade tungsten carbide core bit with an ejector hole.
Graphic displaying the ideal materials for the Bosch SpeedCore thin wall core bit extension, including masonry, brick, block, and concrete.
Angled view of a Bosch thin wall core bit with a pilot bit installed, attached to the 4-inch SDS-plus core bit extension for deep concrete drilling.
Side profile of the Bosch core bit connected to the T3923SC 4-inch SDS-plus extension, demonstrating the seamless two-piece assembly ready for heavy-duty drilling.
Close-up of a worker using a Bosch hammer drill equipped with a masonry bit to precisely drill a hole through a metal electrical box mounted on a concrete block wall.
Worker wearing heavy-duty gloves operating a Bosch hammer drill with a masonry bit to secure a metal electrical junction box to a concrete block wall.
BOSCH

Bosch Core Bit Extension T3923SC SDS Plus 4 Inch 2 Piece SpeedCore Adapter (Heavy Duty Steel Max 600 RPM Deep Concrete Brick Conduit Hole Boring)

In stock
SKU: T3923SC
$14.45 USD

Description

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Bosch T3923SC 4" SDS-Plus SpeedCore™ Thin-Wall Core Bit Extension (2-Piece Set)

The Bosch T3923SC 4-inch SDS-Plus SpeedCore™ thin-wall core bit extension set expands drilling reach across thick poured concrete, CMU masonry blocks, and brick foundation walls. Engineered with a modular two-piece heavy-duty steel adapter interface rated up to 600 RPM, this precision drive assembly couples compact SDS-Plus rotary hammer drills directly to thin-wall core cutters ranging from 1.0 inch up to 4.375 inches in diameter with a 3.0-inch usable cutting depth. Outfitted with precision-machined threads for direct bit attachment without energy loss, full rotary-percussion power transfer geometry, and an SDS-Plus drive shank, it equips commercial electricians, mechanical contractors, and plumbing installers with extended-depth hole-making capability.

Best Used For:

  • Deep Electrical Conduit Wall Penetrations: Adding 4 inches of usable depth to thin-wall core bits to bore clean through-holes in thick structural brick, block, and concrete walls for commercial wiring runs.
  • Plumbing Supply Line and Drain Rough-Ins: Core drilling deep clearance passages through foundation walls and structural masonry for copper lines, PEX tubing, and PVC drain pipes.
  • HVAC Refrigerant Line Set Routing: Boring extended-depth circular pathways through building envelopes and commercial exterior walls for mini-split lines and ductless systems.

Key Performance & Safety Features

  • 4-Inch Extended Drilling Reach: Provides an additional 4 inches of drilling depth, allowing thin-wall core cutters to penetrate deep masonry and foundation barriers.
  • Optimized for Compact SDS-Plus Hammers: Channels rotary-percussion impact force efficiently so smaller rotary hammers can core large holes without motor bogging.
  • Modular Two-Piece Assembly: Threaded two-piece construction enables quick, rigid attachment and detachment of thin-wall core bit heads to minimize jobsite downtime.
  • Broad Diameter Size Compatibility: Supports a wide range of SpeedCore™ thin-wall core cutter diameters from 1.000 inch up to 4.375 inches.
  • 600 RPM Extended Speed Rating: Engineered for stable, high-torque rotation up to 600 RPM when operated in extended configurations.
  • Heavy-Duty Alloy Steel Metallurgy: Industrial-grade forged steel body resists torsional shear and impact fatigue during continuous concrete drilling.

What's Included

  • (1) Bosch T3923SC 2-Piece 4 In. SDS-Plus Thin-Wall Core Bit Extension

Technical Specifications

Manufacturer Brand Bosch Power Tools
Model Part Number T3923SC
Product Tool Classification SpeedCore™ Thin-Wall Core Bit Extension Set
Total Component Piece Count 2-Piece Modular Extension Assembly
Extension Reach Length 4.000 Inches (101.60 mm Usable Extension)
Tool Chuck Interface SDS-Plus® Slotted Universal Quick-Change
Core Bit Compatibility Type Thin-Wall Hollow Core Cutters
Compatible Core Diameter Range 1.000 in. to 4.375 in. (25.40 mm to 111.13 mm)
Usable Cutting Depth Capacity 3.000 Inches (76.20 mm Cutting Depth)
Maximum Rotational Speed 600 RPM (Extended Configuration)
Body Metallurgy Core Heat-Treated Heavy-Duty Structural Alloy Steel
Power Tool Compatibility Corded & Cordless SDS-Plus® Rotary Hammer Drills
Measurement Standard Fractional Imperial (SAE) Standard Dimensions
Suitable for material type Poured Concrete, Masonry Brick, Cinder Block, & Stone

Pro-Tip: When coring deep holes through thick masonry, retract the core bit and extension every 1 to 2 inches to allow accumulated dust and pulverized aggregate to clear the kerf; this keeps operational temperatures low and prevents bit binding.