3 Pieces Step Drill Bit Set Type 78-AG
Punching a clean knockout in a steel electrical enclosure or cutting a conduit entry hole without deforming the panel is exactly what step bits are designed for. This 3-piece Gold Oxide set covers 1/8" through 1-1/8" across three bits, letting you step through multiple hole sizes in thin material with one tool and no pilot drill.
What's Included
- Step bit #1 — 1/8" to 1/2" (covers small conduit and wire entry sizes)
- Step bit #2 — 3/16" to 7/8" (covers mid-range knockout and fitting sizes)
- Step bit #3 — 7/8" to 1-1/8" (covers larger conduit and cable gland sizes)
- 3 pieces total — dual flute, Gold oxide finish, 3 flats on shank
Specifications
| Pieces | 3 |
| Size range | 1/8"–1/2", 3/16"–7/8", 7/8"–1-1/8" |
| Flute design | Dual flute — faster penetration, cleaner exit in thin material |
| Surface treatment | Gold oxide finish |
| Shank | 3 flats — prevents rotation in chuck |
| Type | Type 78-AG step drill |
| Best material | Sheet metal, thin steel plate, aluminum, electrical enclosures |
| SKU | DBSSD00721 |
Best For / Applications
- Electrical enclosures and panels — clean, burr-free knockouts for conduit fittings, grommets, and cable entries
- Sheet metal fabrication — stepping through multiple hole sizes in thin-gauge steel or aluminum without switching tools
- Conduit and EMT installation — cutting clean round entry holes in junction boxes, panel boards, and enclosure walls
- HVAC and plumbing rough-in — thin-wall penetrations in metal ductwork and light-gauge structural members
- Automotive bodywork and custom fabrication — antenna mounts, accessory pass-throughs, and grommet holes in sheet metal
About Step Drill Bits
Step drill bits (also called uni-bits or step bits) are single tools that cut multiple hole sizes in sequence. Each step up the bit is a larger diameter, so you drill to the step that matches the hole size you need and stop — no pilot drill, no hole saw, no multiple tool changes.
The dual flute design on this set creates a special axial and radial cutting geometry that improves penetration speed and produces cleaner holes in thin materials than a single-flute step bit. This matters most in sheet metal and electrical enclosures where a ragged or deformed hole edge can compromise a fitting seal or panel appearance.
Gold oxide finish improves lubricity and extends bit life when drilling repetitively through mild steel. The three flats on the shank keep the bit locked in a keyless chuck — important when the bit is stepping up in diameter and torque demand increases with each pass.
Step bits work best in material up to about 1/4" thick. For thick plate or structural steel, see our Silver & Deming large-diameter set.
Shipping & Ordering
- Ships within 1–2 business days from our warehouse
- Volume pricing available — contact us for multi-unit shop orders
- B2B accounts: Fleet managers, facilities teams, and machine shops can apply for a business account with custom pricing and a dedicated rep — contact us to get started