Diamond Core Drill Bit 1-3/8 in (35mm) - Hardened Stone & Concrete

In this review of the 1-3/8 in (35mm) diamond core drill bit, the bottom line is simple: it is a purpose-built cutter for anyone who needs clean holes in hard stone and masonry without spending on industrial equipment. The bit excels when used on an angle grinder with a 5/8 in-11 arbor and performs best with water to extend life. For homeowners, tile installers, and fabricators working with granite, marble, engineered stone or concrete, this review finds the bit delivers fast cuts and reliable fitment for the right applications.

Key Features

• Laser welded segment: Provides a secure bond between the diamond segment and core body so the bit holds up during aggressive drilling on hard surfaces.
• 35mm diameter (1-3/8 in): Produces a consistent, narrow hole that is useful for plumbing, anchors, and clean fixture passes through stone and masonry.
• Total length 100mm: Gives enough depth for common countertop and wall openings while maintaining rigidity for controlled drilling.
• 5/8 in-11 thread: Fits directly to many angle grinders for quick setup and straightforward attachment without special tooling.
• Dry or wet operation: Can be used without coolant for convenience, but wet use will greatly prolong the segment life and reduce dust.
• Designed for hard materials: Specifically made to cut granite, marble, engineered stone, concrete and brick for trade and DIY tasks.

Who It's For

This bit is aimed at tile setters, countertop fabricators, general contractors, and DIYers who need a compact, hard-stone capable core bit for occasional to moderate use. It is especially useful when paired with an angle grinder that accepts a 5/8 in-11 arbor for fast, on-site hole cutting.

Those who should look elsewhere include users who need very deep holes, high-volume production runs where industrial cores or dedicated drilling rigs are required, or anyone who cannot adapt their drill or machine to the 5/8 in-11 thread without an adapter.

Pros & Cons

Pros

• Fast, clean cutting on hard stone and concrete when used correctly.
• Solid build and laser welded segment contribute to good cut quality and consistent performance.
• Versatile mounting for 5/8 in-11 angle grinders and adaptable to other machines with an adapter.
• Works wet or dry, with wet use significantly extending segment life.

Cons

• Durability is mixed in user experiences; some report long life while others saw breakage after a few uses.
• Requires an adapter to fit SDS, hex, or other non 5/8 in-11 spindles, adding cost for some users.

Specifications

Our Verdict

The 35mm diamond core drill bit is a strong value for tradespeople and serious DIYers who need a compact, hard-material hole saw that fits most angle grinders. Its laser welded build and versatility for wet or dry use make it practical for countertop and masonry tasks, though users should plan for proper cooling and understand that longevity varies with material and technique.

Frequently Asked Questions

Can I use this dry on engineered stone?
Yes, it can be used dry, but using water as coolant is recommended to reduce wear and extend the diamond segment life.

Will it fit my drill?
It fits directly to tools with a 5/8 in-11 thread such as many angle grinders; an adapter is required for SDS, hex, or round shanks.

What materials will it cut?
The bit is designed for hard granite, marble, engineered stone, concrete and brick and performs well on these surfaces when used correctly.