Bosch Step Drill Bit Set SDH30 3-Piece 1/8 to 3/4 Inch High Speed Steel Kit (13 Hole Steps Double Flute 3-Flat Shank Metal HVAC Electrical Boring)

Bosch SDH30 3-Piece High-Speed Steel Step Drill Bit Set (1/8" to 3/4" Range)

The Bosch SDH30 3-piece high-speed steel step drill bit set enlarges electrical knockout openings, bores precision conduit pass-throughs, deburrs sheet metal ducting, and drills clean holes in thin materials up to 1/8-inch thick. Engineered from premium heat-treated high-speed steel with laser-etched depth increments spanning 13 total hole sizes from 1/8 inch to 3/4 inch, these multi-diameter unibits eliminate the need for large index drill sets in sheet steel, aluminum, copper, brass, stainless steel, and PVC. Featuring a self-starting non-walking split point, a balanced dual-flute geometry for chatter-free hole expansion, and 3-flat shanks to prevent chuck slippage under load, this 0.28-lb metalworking set provides commercial electricians, plumbers, and HVAC technicians with fast hole-sizing versatility.

Best Used For:

• Electrical Panel and Junction Box Knockouts: Drilling and stepping up 1/8-inch to 3/4-inch conduit entry holes in electrical enclosures and metal gutters without hole deformation.
• HVAC Sheet Metal and Spiral Ductwork: Boring clean, burr-free take-off ports and sensor probe mounting holes into galvanized duct systems and sheet aluminum.
• Plumbing and Auto Body Thin-Panel Modification: Enlarging radiator bracket holes, trimming fender sheet steel, and penetrating acrylic or copper tubing up to 1/8-inch thickness.

Key Performance & Safety Features

• Multi-Hole Stepped Diameters: Covers 13 unique hole diameters across 3 bits, consolidating full drill bit indexes into a compact jobsite layout set.
• Self-Starting Non-Walking Split Point: Begins cutting instantly on polished sheet metal and stainless steel surfaces without requiring center punches or pilot holes.
• Balanced Double-Flute Geometry: Two precision-ground spiral cutting flutes eject metal chips smoothly to eliminate rotational chatter and bit binding.
• Three-Flat Shank Architecture: Machined 3-flat shank profile locks securely into 1/4-inch and 3/8-inch 3-jaw drill chucks to eliminate shank spinning under torque.
• Industrial High-Speed Steel: Heavy-duty HSS construction maintains cutting-edge hardness and allows for repeated edge re-sharpening over the life of the bit.
• Laser-Etched Diameter Callouts: Highly visible permanent sizing step marks ensure accurate hole sizing inside dim service enclosures.

What's Included

• (1) Bosch SDH1 Step Drill Bit (13 Steps: 1/8", 5/32", 3/16", 7/32", 1/4", 9/32", 5/16", 11/32", 3/8", 13/32", 7/16", 15/32", 1/2" with 1/4" 3-Flat Shank)
• (1) Bosch SDH6 Step Drill Bit (6 Steps: 3/16", 1/4", 5/16", 3/8", 7/16", 1/2" with 3/8" 3-Flat Shank)
• (1) Bosch SDH3 Step Drill Bit (9 Steps: 1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8", 11/16", 3/4" with 3/8" 3-Flat Shank)

Technical Specifications

Pro-Tip: Apply a drop of cutting fluid or tapping oil when stepping through stainless steel or heavy-gauge galvanized duct; keeping the double-flute cutting edges cool preserves edge sharpness and extends the time between bit re-sharpening.