3-8mm Sintered Diamond Core Drill Bit Set, 5 Pcs – Durable & Efficient for Gemstone, Glass & Ceramic Cutting

Overview — 5-Piece Professional Sintered Diamond Core Drill Set

The 5-Piece Sintered Diamond Core Drill Set (3mm, 4mm, 5mm, 6mm, 8mm) is engineered for high-performance drilling and core extraction in ultra-hard materials including gemstone, agate, jade, glass, ceramics, porcelain tile, and granite. Unlike electroplated bits with only a surface layer of abrasive, these sintered diamond core drills feature a solid, metal-bonded matrix with diamonds embedded throughout the entire cutting wall, delivering up to 3 to 5 times longer tool life and continuous self-sharpening performance.

Key Features

• Complete 5-Size Assortment: Includes 3mm, 4mm, 5mm, 6mm, and 8mm outer diameter drills, covering essential micro-drilling, stringing hole, water passage, and mounting applications.
• Solid Sintered Diamond Matrix: Heavy-duty metal bond holds diamond crystals uniformly throughout the segment wall, maintaining sharp cutting edges across hundreds of drilling cycles.
• Hollow Annulus Core Extraction: Thin-wall core geometry cuts only a narrow kerf around the circumference, drastically reducing cutting resistance, heat buildup, and edge chipping.
• Straight Standard Shank: Precision concentric shank fits standard rotary tools, bench drill presses, water-swivel chucks, and CNC spindle attachments.

Applications

• Lapidary & Gemstone Working: Drilling precision pendant holes, bead channels, and core plugs in agate, quartz, jasper, sapphire, and jade.
• Glass & Tile Cold Working: Clean entry and breakout in stained glass, fused glass bottles, ceramic tiles, and porcelain slabs without micro-fracturing.
• Stonework & Geological Sampling: Sampling and anchoring in granite, marble, and composite hard stones.

Operating Guidelines

• Always Use Water Cooling: Constant water feed or submersion is required to lubricate the cut, flush away slurry, and prevent diamond thermal degradation. Never run dry.
• 45-Degree Initial Entry: Start the drill at a 45° angle to create a crescent groove on the material surface to eliminate bit skating, then slowly pivot the tool perpendicular (90°) once the channel is established.
• Gentle Pulsing Pressure: Apply light, steady pressure and periodically pulse the drill up and down to allow water to flush out accumulated rock and glass slurry.