HSS Taper Shank Drill Bits

Not by catalog name alone. We can often propose a standard DIN 345 or DIN 1870 M2/M35 alternative, but exact copies of special point geometry, non-standard flute length, high-helix designs, or unusual Morse taper assignments need drawings, test criteria, and enough quantity to justify development. For small trial quantities, a documented standard alternative is usually the responsible path.

A Morse Taper (MT) is a self-holding tapered shank system used on machine tools. The taper angle (approximately 1.5°) creates a friction fit that holds the drill securely without a chuck. The drill is inserted into the machine spindle and self-locks under drilling force. To remove, a drift key (wedge) is inserted through a slot in the spindle to push the tang and eject the drill. MT sizes range from MT1 (smallest) to MT5 (largest), with each size handling specific diameter ranges.

Standard MT size assignments per DIN 345:

MT1: Ø6.0 – 13.8mm (spindle bore ~12.065mm)
MT2: Ø14.0 – 23.0mm (spindle bore ~17.780mm)
MT3: Ø23.2 – 31.5mm (spindle bore ~23.825mm)
MT4: Ø32.0 – 50.0mm (spindle bore ~31.267mm)
MT5: Ø51.0 – 76.0mm (spindle bore ~44.399mm)

If your machine spindle has a larger taper than the drill requires, use a taper sleeve adapter (e.g., MT2 to MT3 adapter) to step up. Never use a drill in a spindle that's too small — the taper won't seat properly.

Use taper shank drills when:

1. Diameter exceeds 13mm — straight shank drills above 13mm require reduced shanks which reduce rigidity. Taper shanks provide full cross-section strength.

2. Using machine tools — drill presses, lathes, milling machines, and radial arm drills are designed for Morse taper tooling. The self-holding taper eliminates chuck slippage under heavy loads.

3. Heavy-duty drilling — taper shanks transmit higher torque than chucks can grip. Essential for deep holes, large diameters, and hard materials.

4. Precision matters — the taper provides superior concentricity (runout < 0.02mm) compared to 3-jaw chucks.

Use straight shank drills for: handheld power drills, CNC machines with collet systems, diameters below 13mm, and quick-change applications.

Never hammer the drill or pry it out — this damages both the drill and spindle.

Correct method:
1. Locate the drift slot — a rectangular opening through the spindle body.
2. Insert a taper drift key (flat wedge tool) through the slot.
3. Align the drift with the tang (flat end) of the drill.
4. Tap the drift gently with a hammer — the drill will pop free.
5. Catch the drill — do not let it fall onto the machine table or floor, as this damages the taper surface.

Always keep taper surfaces clean and lightly oiled. Nicks, burrs, or rust on the taper will cause poor fit, runout, and ejection problems. Repair minor damage with a taper reamer.

Taper sleeve adapters (reduction sleeves) allow a smaller MT drill to fit a larger MT spindle. Standard combinations:

MT1 → MT2 (most common for Ø12–14mm drills in MT2 machines)
MT1 → MT3
MT2 → MT3 (common for bench drill presses)
MT2 → MT4
MT3 → MT4 (common for radial arm drills)
MT3 → MT5
MT4 → MT5

Sleeves are hardened steel, precision ground to maintain concentricity. Each sleeve has its own tang for ejection. Stack sleeves carefully — avoid using more than one adapter (reduces rigidity and increases runout).

We can supply standard DIN 2185 taper sleeves alongside drill bit orders.

DIN 345 (Standard Length): The most common taper shank drill standard. Provides a balanced ratio of flute length to overall length for general-purpose drilling. Suitable for most industrial applications up to ~3× diameter drilling depth.

DIN 1870 (Extra Long): Extended flute length for deep hole drilling. Approximately 50% longer flute than DIN 345. Used for: deep hole drilling, through-hole applications in thick workpieces, and situations where standard length drills cannot reach. Requires more frequent chip evacuation (pecking cycles) and rigid machine setup to prevent deflection.

Both standards use the same Morse taper shank sizes — only the flute and overall length differ.

Yes — M35 Cobalt (5% Co) taper shank drills are the recommended choice for stainless steel on machine tools.

Key parameters for stainless steel drilling:
- Cutting speed: 10–15 m/min (lower for 316, higher for 304)
- Feed rate: 0.15–0.30 mm/rev (depending on diameter)
- Point angle: 135° split point (self-centering, reduces thrust)
- Coolant: Flood coolant with sulfur-based cutting oil — mandatory
- Technique: Constant feed pressure, never dwell (work-hardening)

The Morse taper shank provides two advantages over straight shank for stainless steel: (1) zero slippage under the high torque required, and (2) superior rigidity for consistent chip formation. Expected tool life: 50–100+ holes in 304 stainless depending on diameter and depth.