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7.7 NWKc HSS metal drill bit - Artykuły Techniczne
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  • 7.7 NWKc HSS metal drill bit - Artykuły Techniczne
  • 7.7 NWKc HSS metal drill bit - Artykuły Techniczne - nr. 1
Artykuły Techniczne

Metal drill bit 7.7 NWKc HSS DIN 345

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Net price: €3.68

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Description

DIAMETER Ø7.7 mm
MORSE TAPER MT1
OVERALL LENGTH 156 mm
FLUTE LENGTH 75 mm

Technical specifications of the Ø7.7 mm drill bit

Twist drill with Morse taper shank

TECHNICAL DATA
Diameter Ø7.7 NWKc HSS
Standard DIN 345
Drill type NWKc — twist drill with taper shank
Material HSS (high-speed steel)
Overall length l1 156 mm
Flute length l2 75 mm
Morse taper MT1
Point angle 118°
Diameter tolerance h8
Cutting direction Right-hand

Ø7.7 mm HSS metal drill bit – Morse taper MT1

Product description and key benefits

The Ø7.7 mm NWKc twist drill is distinguished by its mounting method — the MT1 Morse taper eliminates the intermediate component between the tool and the spindle. This results in lower radial runout and improved repeatability of hole dimensions. The Ø7.7 Morse taper drill with a high-speed steel (HSS) cutting edge retains its working hardness up to 600°C, allowing drilling without the risk of tempering the cutting edge.

Key benefits of the Ø7.7 mm metal drill bit

  • Eliminates the drill chuck — the MT1 taper seated directly in the spindle shortens the torque transmission path and reduces radial tool runout
  • Heat resistance up to 600°C — the high-speed steel cutting edge retains its working hardness even at higher cutting speeds in soft and medium-hard steels
  • Interchangeability to DIN 345 — identical taper dimensions across manufacturers allow drill replacement without calibrating the spindle axis
  • Short design (l1 = 156 mm) — reduced tool overhang provides greater rigidity and a better hole surface finish than extended-length drills
  • Holes for locating pins and bushings — the h8 tolerance grade provides a repeatable preliminary size before finish reaming to an H7 fit
  • Low operating cost — can be resharpened repeatedly on a tool grinder without losing cutting geometry while maintaining the 118° angle

The Ø7.7 mm Morse taper drill is selected for repair and assembly work on pillar drilling machines. The tool allows fast drilling of through and blind holes in steels with tensile strengths up to 900 N/mm². H12 tolerance at Ø7.700–Ø7.850 mm provides dimensional accuracy sufficient for most bolted connections.

Morse tapers – dimensions to DIN 228

Dimension table for all Morse tapers MT0–MT6

TaperDiameter D [mm]Length [mm]
MT0 9.045 49.8
MT1 12.065 53.5
MT2 17.780 64.0
MT3 23.825 80.5
MT4 31.267 117.5
MT5 44.399 149.5
MT6 63.348 210.0



REDUCTION SLEEVES COMPATIBLE WITH THE Ø7.7 MM DRILL BIT:

✓ MT1 → MT2 — for a spindle with an MT2 socket
✓ MT1 → MT3 — for a spindle with an MT3 socket
✓ MT1 drill drift — for removing the drill bit from the spindle

Cutting data for the Ø7.7 mm drill bit according to ISO 513

Recommended machining conditions for a diameter of Ø7.7 mm

ISO symbolWorkpiece materialVc [m/min]f [mm/rev]n [rpm]Vf [mm/min]
P Steel Structural steel up to 900 N/mm² 11÷20 0.08 455÷827 36÷66
K Cast iron Gray cast iron GG20–GG30 13÷16 0.08 537÷661 43÷53
N Copper and Al alloys Cu, CuZn, Al, and alloys 25÷28 0.10÷0.12 1033÷1157 103÷139

Drill sharpening

Sharpen the Ø7.7 mm drill bit on a tool grinder, maintaining the 118° point angle and cutting edge symmetry. Asymmetric sharpening enlarges the hole diameter and loads the spindle unevenly. Each sharpening reduces the flute length by approximately 1–2 mm.

Material compatibility of the Ø7.7 mm drill bit

Range of workpiece materials and application limitations

✓ Structural steel (S235, S355) up to 900 N/mm²
✓ Gray and ductile cast iron (GG20, GGG40)
✓ Low-carbon and medium-alloy steel
▲ Stainless steel (Vc reduced by 40%, ample coolant)
▲ Aluminum and Al alloys (emulsion coolant required)
✗ Hardened steels above 45 HRC

Frequently asked questions about the Ø7.7 mm drill bit

The maximum drilling depth is the flute length l2 = 75 mm minus the drill point length (approximately 2 mm). The effective usable depth is therefore approximately 73 mm.

In S235/S355 structural steels, spot drilling is not necessary — the 118° angle provides self-centering. Spot drilling with an NC 90° drill is recommended when drilling on milled surfaces, castings with machining allowance, or difficult-to-machine materials.

A cooling and lubricating emulsion at a concentration of 5–8% is recommended. For stainless steels, increase the concentration to 8–10%. Cast iron can be drilled dry with compressed air to remove chips.

Product accessories

Morse drift MK1-2

Reference: 0000012383 In stock > 10 items

€3.95

€4.86 brutto

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Metal drill bit 7.7 NWKc HSS DIN 345

Metal drill bit 7.7 NWKc HSS DIN 345

Shipping

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