The Simpson MDMX08121Q 13/16 in. x 21 in. SDS-max Shank Quad-Head Drill Bit from Simpson Strong-Tie is a premium, professional-grade carbide rotary hammer bit engineered for demanding concrete and reinforced concrete drilling applications. Its proprietary quad-head dual-cutter design, high-volume double-helix flute geometry, and patented reinforced core work together to maximize energy transfer from the rotary hammer into the bit tip - delivering faster drilling speeds, longer service life, and measurably reduced noise, stress, and vibration on the operator. Precision-engineered and conforming to ANSI Standard B212.15, this SDS-max bit is built to perform where accuracy and durability are non-negotiable.

Key Features

• Uniformly brazed carbide inserts - secure, consistent bonding across the cutting edges extends bit life and maintains cutting performance over repeated use
• Self-centering tips - locate accurately at the point of contact, reducing walking and ensuring precise hole placement in concrete surfaces
• Chromium-nickel-molybdenum steel alloy body - provides the toughness and impact resistance needed to sustain hammering quality through extended, heavy-duty service
• Heat-treatment procedures and shot-peened finish - increase surface hardness, improve resistance to bending forces, reduce bit wear, and contribute to faster drilling speeds
• High-volume, multi-flute spiral - rapidly channels concrete dust out of the hole during drilling, keeping the cutting zone clear and maintaining consistent drilling speed
• 4 x 90 deg. quad-head geometry - crushes through rebar and prevents the bit from sticking in reinforced concrete, keeping work moving without interruption
• Patented, high-performance reinforced core flute - maximizes energy transfer from the rotary hammer to the bit tip, boosting drilling efficiency and reducing operator fatigue
• Conforms to ANSI Standard B212.15 - meets recognized industry standards for dimensional accuracy and compatibility, giving professionals confidence in fit and performance

Why This Product

• Built specifically for reinforced concrete - the 4 x 90 deg. quad-head dual-cutter design is engineered to crush through rebar and resist sticking, making this bit a reliable choice for anchor installation and structural drilling in rebar-laden slabs and walls
• Engineered to reduce operator strain - the proprietary flute geometry optimizes impact energy transfer and actively reduces vibration, noise, and physical stress on the operator during prolonged rotary hammer use
• Durability built into every layer - from the uniformly brazed carbide inserts and chromium-nickel-molybdenum alloy body to the heat-treated, shot-peened finish, multiple reinforcing processes work together to extend service life and resist wear under repeated heavy impact
• Precision performance from a trusted name in structural products - Simpson Strong-Tie backs this bit with ANSI Standard B212.15 compliance and a design that pairs drilling speed with accuracy, giving contractors and tradespeople a dependable tool for critical concrete drilling tasks

Specifications

• Model Number (MPN): MDMX08121Q
• Brand: Simpson Strong-Tie
• Shank Type: SDS-max Shank
• Head Type: Quad Head - 4x Drill Bit
• Diameter: 13/16 in.
• Overall Length: 21 in.
• Drilling Depth: 17 in.
• Material: Hardened Steel (Chromium-Nickel-Molybdenum Steel Alloy Body with Carbide Inserts)
• Standard Compliance: ANSI Standard B212.15
• Country of Origin: Germany

Frequently Asked Questions

What type of rotary hammer is this drill bit compatible with?

This drill bit features an SDS-max shank, which is designed to fit SDS-max rotary hammers. The SDS-max shank interface is a standard connection used across a wide range of professional-grade rotary hammer tools.

What is the actual drilling depth of the MDMX08121Q?

While the overall length of this drill bit is 21 in., the effective drilling depth is 17 in. This distinction is important when planning hole depths for anchor installations or other precise applications.

How does the quad-head design benefit drilling in reinforced concrete?

The 4 x 90 deg. quad-head geometry is specifically engineered to crush through rebar and prevent the bit from sticking in reinforced concrete. Combined with the high-volume double-helix flute design and patented reinforced core, the quad-head configuration improves both drilling speed and durability in tough, rebar-laden substrates.

What makes the body material of this drill bit particularly durable?

The drill bit body is constructed from a chromium-nickel-molybdenum steel alloy, which ensures hammering quality and extended service life. Additional heat-treatment procedures and a shot-peened finish further increase surface hardness, improve resistance to bending forces, and reduce overall drill bit wear during heavy use.

Note: Product dimensions may differ from picture. Please see the item description above for specifications.