Diamond drill bit Proxxon 28844 — 20 mm diameter, single piece

Proxxon 28844 — 20 mm diameter single-piece diamond drill bit is designed for precise drilling and cutting of hard and brittle materials. The diamond-coated cutting edge provides wear resistance and long service life for tasks that require clean, accurate holes. The bit includes a mandrel with a 3/32" (2.35 mm) shank and a 20 mm wheel, and cooling holes reduce heat build-up for burr-free results without burn marks.

Advantages

The single-piece construction ensures stability and reduced vibration during operation, improving hole accuracy. Diamond abrasive at the working end delivers efficient material removal on glass, ceramics, porcelain and other hard substrates. Integrated cooling holes lower friction and temperature, which minimizes chipping and prevents thermal damage to sensitive workpieces. The included mandrel with a 2.35 mm shank makes the bit compatible with a wide range of handheld and bench drills fitted for that shank size.

Suitable for

• Drilling clean holes in glass and ceramics
• Cutting and shaping porcelain and tiles
• Working on fiberglass and plastics without excessive melting
• Precision tasks on non-ferrous metals and steel where small-diameter holes are needed
• Deburring and grinding edges of brittle materials

Key specifications

• Cutting diameter: 20 mm
• Tool type: single-piece diamond drill bit
• Shank size: 3/32" (2.35 mm) mandrel included
• Abrasive: diamond-coated working edge
• Cooling: holes in the bit design to reduce heating
• Typical materials: glass, porcelain, ceramics, fiberglass, plastics, non-ferrous metals, steel

How to use

Secure the mandrel with its 2.35 mm shank in the drill chuck and clamp the workpiece to prevent movement. Begin drilling at low to moderate speed, using steady pressure and keeping the drill perpendicular to the surface. For brittle materials such as glass and ceramics, use water or another coolant to further reduce heat and flush debris from the cutting area. Avoid excessive force; allow the diamond abrasive to cut progressively. After completing the hole, slow the drill before withdrawing the bit to prevent chipping at the exit point.

Usage recommendations

Use consistent cooling (water or a commercial coolant) when working on glass, porcelain or ceramic tiles. Start with a pilot indentation or use masking tape to help prevent slipping. Wear appropriate personal protective equipment such as safety glasses and gloves, and follow the drill manufacturer's instructions for maximum operating speed for a 2.35 mm shank accessory.