Drill high-precision pilot holes for dense micro-pavé layouts through tough precious metals and refractory alloys without bit flex, wandering, or premature breakage. The Busch® 4205S-AU Series Carbide Twist Drill Bur is an industrial-grade micro-drilling tool engineered specifically for diamond setters, fine goldsmiths, and precision micro-mechanics.
Engineered specifically for the manufacture of precise pavé settings, the 4205S-AU features a specialized shortened working flute geometry with an ultra-rigid web core. By reducing the working flute length (3.00 mm to 4.50 mm) compared to standard twist drills, this tool maximizes torsional rigidity and eliminates lateral bit deflection during microscope-guided freehand starts. The cutting head incorporates a precision 2-groove design with ground edge bevels (top view: 2 grooves + bevel). These integrated secondary bevels stabilize the drill within the hole, dampening vibration and preventing corner fracturing when cutting through tough metals like platinum, titanium, and stainless steel. Machined from finest-grain solid tungsten carbide (Feinstkornhartmetall), each bit delivers dependable edge sharpness and thermal wear resistance. Finished with a gold identification ring and an industry-standard 2.35 mm (3/32") reinforced shank, the series drops directly into flexible shaft handpieces, precision bench micromotors, and quick-change bench systems. Available in an essential 6-size pavé progression from 0.50 mm to 1.00 mm (4205S-AU-005 to 4205S-AU-010), supplied as a single-piece package (1 pc/pack).
Why Choose Busch® 4205S-AU Short-Flute Pavé Drills
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Specialized Short Working Flutes: Shorter flute lengths (3.00 mm to 4.50 mm) deliver extreme structural stiffness, eliminating bit deflection and preventing snapped tips during pavé layout drilling.
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Dedicated Pavé Setting Architecture: Engineered specifically to drill clean, perpendicular pilot seats for micro-diamonds without tearing delicate bead partitions.
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2-Groove Fluting with Edge Bevels: Secondary protective bevels guide the cutting head along borehole walls to eliminate chatter and prevent snagging in tough alloys.
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Finest-Grain Solid Carbide: Delivers high wear resistance and edge retention, outlasting standard tool steel and HSS drills in abrasive and work-hardened metals.
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Broad Hard-Metal Capability: Cuts through steel, platinum, titanium, hard metal alloys, white gold, yellow gold, and silver.
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Distinctive Gold Band ID: Finished with a signature gold identification ring on the shank neck for immediate visual recognition at the workbench.
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Universal 2.35 mm (3/32") Shank: Provides seamless compatibility across standard jewelry flexible shafts, bench micromotors, and quick-change handpieces.
Technical Specifications & Product Matrix
| Parameter Metric | Certified Factory Specification |
| Brand |
Busch® |
| Product Series Number |
4205S-AU Twist Drill Bur (Pavé-Spiralbohrer) |
| Head Material |
Finest-Grain Solid Tungsten Carbide (Feinstkornhartmetall) |
| Shank Diameter |
Standard 2.35 mm (3/32 in) Reinforced Shank |
| Flute Architecture |
Short-Flute 2 Grooves + Edge Bevels (2 Nuten + Fasen) |
| Available Diameters (D) |
0.50 mm to 1.00 mm (6 Calibrated Pavé Sizes) |
| Flute Working Length (L) |
3.00 mm (005–006), 3.50 mm (007–008), 4.50 mm (009–010) |
| Recommended Speed Range |
3,000 – 5,000 RPM |
| Packaging Unit |
Pack of 1 |
Free Global Shipping
We process orders within 1-3 business days. Estimated standard international delivery is 6-12 business days.
14-Day Returns
We have a 14-day return policy. Items must be unused, with all original accessories, and in original packaging.
For full details, please refer to our Shipping and Refund policies at the bottom of the page.
