Drill Bit Makita D-44476 25 mm Diamond Core Bit for Granite Marble Tile

The Makita D-44476 25 mm Diamond Core Bit for Granite Marble Tile is a precision cutting accessory designed for creating clean 25 mm diameter cores in hard surfaces such as granite, marble and ceramic tile. Manufactured for compatibility with drills that accept threaded core bits, this diamond-tipped bit is intended to deliver accurate, durable cutting performance for renovation, tiling and stone-working tasks. It can be used in wet or dry drilling applications where diamond core bits are recommended, with best results when matched to a suitable drill and correct technique.

Advantages

The diamond-segment cutting edge provides high wear resistance and consistent cutting across abrasive stone and tile surfaces. The 25 mm diameter gives a standard core size useful for pipes, anchor holes and sample extraction. Its threaded shank fits common M14-style holders for secure attachment to compatible drills, and the solid construction reduces bit flex for straight, accurate cores. Designed by a recognized tool manufacturer, the bit is made specifically for hard materials where conventional bits wear quickly.

Suitable for

• Drilling 25 mm cores in granite and marble countertops and tiles
• Creating holes for plumbing or electrical passes through tiled walls
• Sample cutting and small core extraction from natural stone
• Renovation and tile installation work requiring precise circular holes

When it may not be suitable

This diamond core bit is intended for use on hard mineral surfaces; it is not suitable for general-purpose wood or metal drilling where standard twist or spade bits are more appropriate. For very large diameter holes or heavy production work, larger core bits or purpose-built drilling rigs may be preferable. Performance depends on using the correct drill speed, feed pressure and cooling method—improper technique can shorten bit life or produce poor results.

Key specifications

• Cutting diameter: 25 mm
• Material: diamond-segment cutting edge suitable for stone and tile
• Intended surfaces: granite, marble, ceramic tile and other hard stone materials
• Mount type: threaded shank compatible with common M14-style drill holders
• Suitable operating modes: wet or dry drilling when diamond bits are recommended

How to use

Secure the Makita D-44476 in a compatible drill or holder according to the drill manufacturer’s instructions. Mark the drilling position, start at low speed to position the bit and establish a pilot groove, then increase speed as appropriate for the material. Use steady, moderate pressure to allow the diamond segments to cut without binding. For wet drilling, apply continuous water cooling to reduce heat and extend bit life; for dry drilling, use intermittent drilling and allow the bit to cool between passes. Keep the drill perpendicular to the surface to ensure a straight core.

What to consider before purchase

• Confirm drill compatibility with a threaded shank (M14-style) and recommended RPM range for diamond core bits
• Verify the target material is suitable for diamond core drilling (granite, marble, tile, etc.)
• Decide whether you will use wet cooling or dry intermittent drilling based on site conditions
• Consider spare bits if performing multiple holes or heavy work to avoid downtime

Usage recommendations

For best results, pair the Makita D-44476 25 mm diamond core bit with a drill that provides stable rotation and variable speed control. Use water cooling on stone and tile wherever possible to prolong bit life and maintain cutting efficiency. Begin with a slow approach to prevent skidding on glazed surfaces, and allow the bit to cool periodically during extended dry drilling.