13 Pcs M35 Cobalt HSS Three Flute Drill Bit Set Steel 1/16in – 1/4in 135°
13PCS HSS-Cobalt Drill Bits (M35) — Three-Flute, 135° Split Point, 1/16"–1/4"
For Hard Metal, Hardened Stainless Steel, and Cast Iron • Jobber Length • Round Shank
Built for difficult jobs, this 13-piece M35 cobalt HSS (≈5% Co) set uses a three-flute twist plus a 135° split point to bite instantly, self-center, and hold a stable path through hardened stainless, cast iron, and alloy steels. Fully-ground bodies control runout for rounder holes and longer life. Jobber-length round shanks fit any 3-jaw chuck; a compact metal index case keeps the kit organized.
Why this set wins on hard materials
Three-flute stability: Extra land support reduces chatter and ovality; chips break smaller—ideal for cast iron and austenitic stainless.
135° split-point: Self-centers, reduces walking on curved/painted surfaces, lowers thrust at breakthrough.
M35 cobalt core: High red-hardness maintains a sharp edge at temperature; optional TiAlN/AlTiN coatings for extreme duty.
Precision-ground flutes: Better concentricity and smoother chip evacuation = cleaner holes and fewer regrinds.
Pro tip: On stainless and deep holes, run lower RPM with cutting oil and peck to manage heat and chips.
Expanded, search-intent–friendly applications
Automotive/MRO: Drilling out broken studs/bolts (extractor prep), exhaust/manifold brackets, chassis/frame work, stainless trim, accessory mounts.
Fabrication/Metalwork: Fixture plates, angle/channel, enclosure panels, tap-drill pilots for threading hard steels.
Cast Iron Components: Gearbox housings, pump bases, machine feet—controlled entry/exit with reduced edge chipping.
Electrical/HVAC: Panel knockouts (pilot), stainless cabinets, bracket and conduit mounts.
Maintenance Teams: Plant repairs on alloy steel frames, guard rails, tool steel fixtures (when hardness permits).
Product Specifications
| Feature | Details |
|---|---|
| Material | HSS-Cobalt M35 (~5% Co) |
| Geometry | Three-flute twist, 135° split-point (web-thinned) |
| Body | Fully ground for tight runout and clean surface finish |
| Length Type | Jobber (ANSI / DIN 338 equivalent) |
| Shank | Round, fits standard 3-jaw chucks |
| Finish | Bright ground (optional: TiAlN / AlTiN / Black & Gold) |
| Recommended Materials | Hardened stainless (304/316), alloy & carbon steels, cast iron, non-ferrous |
| Storage | Metal (or heavy-duty ABS) indexed case with labeled sizes |
| Resharpenable | Yes — maintain split-point and 3-flute symmetry |
Size Map with Overall Length (OAL) & Flute Length (FL) — 13 pcs (Inch)
| Size (in) | Metric (mm) | OAL (in) | FL (in) |
|---|---|---|---|
| 1/16 | 1.59 | 1.875 | 0.875 |
| 5/64 | 1.98 | 2.000 | 1.000 |
| 3/32 | 2.38 | 2.250 | 1.125 |
| 7/64 | 2.78 | 2.375 | 1.250 |
| 1/8 | 3.18 | 2.750 | 1.625 |
| 9/64 | 3.57 | 2.875 | 1.750 |
| 5/32 | 3.97 | 3.000 | 2.000 |
| 11/64 | 4.37 | 3.125 | 2.125 |
| 3/16 | 4.76 | 3.500 | 2.375 |
| 13/64 | 5.16 | 3.625 | 2.500 |
| 7/32 | 5.56 | 3.750 | 2.625 |
| 15/64 | 5.95 | 3.875 | 2.750 |
| 1/4 | 6.35 | 4.000 | 2.750 |
Quick speed & coolant guide (rule-of-thumb)
| Material | Speed Guidance | Coolant |
|---|---|---|
| Hardened Stainless (304/316) | Low–moderate RPM; steady feed; peck on deep holes | Cutting oil required |
| Alloy/Carbon Steel | Moderate RPM; avoid rubbing | Cutting oil recommended |
| Cast Iron | Moderate RPM; controlled feed | Dry or minimal oil |
| Aluminum/Brass | Higher RPM; light feed | Light oil optional |
Packaging & OEM
Indexed case (metal/ABS), retail sleeve + barcode; master cartons for distributors.
Private label: laser-etched logo, custom size maps, coatings, bilingual EN/RU labels & spec sheets.
FAQ
Q1: Three-flute vs. two-flute — what’s the benefit?
The third flute adds rigidity and reduces chatter, producing rounder holes and smaller chips in hard materials; feed rates may be slightly lower than 2-flute in deep drilling.
Q2: Will these handle hardened stainless?
Yes. Use lower RPM, cutting oil, and peck cycles. For extreme hardness (>HRC 45), consider M42 cobalt.
Q3: Impact-driver compatible?
Round shanks are for 3-jaw chucks. Ask for hex-shank versions if needed.
Q4: Can I get TiAlN coating?
Yes—TiAlN/AlTiN coatings are available for higher heat resistance and dry cutting.
Get in Touch
Have questions about our products or want to discuss a custom order? Our team is ready to help you.