Drill refractory precious metals, pierce tough alloy plates, and machine precision pilot holes without drill deflection, wandering, or edge breakout. The Busch® 4203S-AU Series Carbide Twist Drill Bur is an industrial-grade micro-drilling tool engineered for goldsmiths, platinum setters, and precision metalworkers machining dense and gummy alloys.
Unlike standard twist drills that struggle with work-hardened metals, the 4203S-AU features a specialized 2-groove geometry with integrated bevels and reinforced web architecture. This cutting geometry balances aggressive penetration with reinforced edge strength, allowing the drill to pierce steel, platinum, titanium, hard metal alloys, gold, and silver cleanly without binding or chattering. Sintered from finest-grain solid tungsten carbide (Feinstkornhartmetall), these drills offer high torsional rigidity, thermal wear resistance, and long edge life. Fitted with a gold identification ring and an industry-standard 2.35 mm (3/32") reinforced shank, the series seats directly into jeweler flexible shaft handpieces, precision micromotors, and upright drill presses without collet changes. Available in 12 calibrated sizes from 0.50 mm to 1.60 mm (4203S-AU-005 to 4203S-AU-016), supplied as a single-piece package (1 pc/pack).
Why Choose Busch® 4203S-AU Carbide Hard-Metal Twist Drills
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2 Grooves + Bevel Architecture: Engineered fluting with edge-strengthening bevels provides cutting lip stability when piercing hard, abrasive, or gummy alloys.
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Finest-Grain Solid Carbide: Delivers high hardness and thermal wear resistance, outlasting conventional HSS drills across demanding platinum and steel drilling runs.
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Broad Alloy Penetration: Drills cleanly through platinum, titanium, stainless steel, hard gold alloys, and sterling silver.
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Reinforced Core Stability: Heavy-duty web construction eliminates drill flex and runout, ensuring straight bores without hole distortion.
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Gold Band Visual ID: Finished with a distinctive gold ring on the shank neck for quick bench identification.
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Universal 2.35 mm (3/32") Shank: Provides direct compatibility across standard jewelry flexible shafts, micromotors, and precision bench drills.
Technical Specifications
| Parameter Metric | Certified Factory Specification |
| Brand Authority |
Busch® |
| Product Series Number |
4203S-AU Twist Drill Bur (Vollhartmetall-Spiralbohrer) |
| Head Material |
Finest-Grain Solid Tungsten Carbide (Feinstkornhartmetall) |
| Shank Diameter |
Standard 2.35 mm (3/32 in) Reinforced Shank |
| Flute Architecture |
2 Grooves + Bevel (2 Nuten + Fasen) |
| Available Diameters (D) |
0.50 mm to 1.60 mm (12 Individual Sizes) |
| Flute Working Length (L) |
6.00 mm (005–006), 7.00 mm (007–008), 9.00 mm (009–016) |
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.
