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Drill 3.9 NWKc HSS DIN 345
5221
Diameter (mm): 3,9301 sizes of this drill
33,13,23,33,43,53,63,73,83,944,14,24,34,44,54,64,74,84,955,15,25,35,45,55,65,75,85,966,16,26,36,46,56,66,76,86,977,17,157,27,257,37,47,57,67,77,757,87,988,18,28,258,38,48,58,68,78,88,999,19,29,259,39,49,59,69,79,759,89,91010,110,210,310,410,510,610,710,7510,810,91111,111,211,2511,311,411,511,611,711,811,91212,112,212,312,412,512,612,712,812,91313,113,213,2513,313,413,513,613,713,7513,813,91414,2514,414,514,751515,2515,515,751616,2516,516,751717,2517,517,751818,2518,518,751919,2519,519,752020,2520,520,752121,2521,521,752222,2522,522,752323,2523,523,752424,2524,524,752525,2525,525,752626,2526,526,752727,2527,527,752828,2528,528,752929,2529,529,753030,2530,530,753131,2531,531,753232,2532,532,753333,2533,533,753434,2534,534,753535,2535,535,753636,2536,536,753737,2537,537,7537,83838,538,753939,2539,539,754040,2540,54141,54242,54343,54444,54545,54646,546,75474848,54949,55050,55151,55252,553545556575858,55960616263646566676869707172737475767778798081828384858687888990919293949596979899100
€4.05 tax inc.
Net price: €3.29
Description
DIAMETER Ø3.9 mm
MORSE TAPER MT1
OVERALL LENGTH 124 mm
FLUTE LENGTH 43 mm
Technical specifications of the Ø3.9 mm drill bit
Twist drill with Morse taper shank
| TECHNICAL DATA | |
|---|---|
| Diameter | Ø3.9 NWKc HSS |
| Standard | DIN 345 |
| Drill type | NWKc — twist drill with taper shank |
| Material | HSS (high-speed steel) |
| Overall length l1 | 124 mm |
| Flute length l2 | 43 mm |
| Morse taper | MT1 |
| Point angle | 118° |
| Diameter tolerance | h8 |
| Cutting direction | Right-hand |
Ø3.9 mm HSS metal drill bit – Morse taper MT1
Product description and key benefits
The Ø3.9 mm twist drill with an MT1 taper shank conforming to DIN 345 is a basic tool for any pillar drilling machine. Its cutting geometry with a 118° point angle provides self-centering in soft and medium-hard steels without spot drilling. The Ø3.9 Morse taper drill is used to produce mounting holes, through holes, and holes for tapping in metalworking shops and maintenance departments.
Key benefits of the Ø3.9 mm metal drill bit
- MT1 taper — direct mounting — eliminates the drill chuck as a source of radial runout and tool slippage
- HSS cutting edge, 63–65 HRC — hardness that ensures stable cutting of steels with tensile strengths up to 900 N/mm² throughout the interval between sharpenings
- Right-hand helical flutes — effective chip evacuation from the cutting zone — essential when drilling holes deeper than 2×D
- Compact 124 mm design — shorter tool overhang provides greater rigidity and less vibration
- Repeated reconditioning — the HSS cutting edge can be resharpened 8–12 times while retaining its geometry — at l2 = 43 mm, the resharpening allowance is approximately 5 mm
- Sleeve compatibility — use on drilling machines with MT1 to MT2 spindles using reduction sleeves
The Ø3.9 Morse taper drill bit is most often selected for mounting holes in hollow sections, thick plates, and machine components. In toolrooms, it is used to prepare preliminary holes before reaming to a dowel pin fit. Holes are produced to tolerance class H12 (Ø3.900–Ø4.020 mm); if class H7 is required, additional reaming is necessary.
Morse tapers – dimensions to DIN 228
Dimension table for all Morse tapers MT0–MT6
| Taper | Diameter 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 Ø3.9 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 Ø3.9 mm drill bit according to ISO 513
Recommended machining conditions for a diameter of Ø3.9 mm
| ISO symbol | Workpiece material | Vc [m/min] | f [mm/rev] | n [rpm] | Vf [mm/min] |
|---|---|---|---|---|---|
| P Steel | Structural steel up to 900 N/mm² | 11÷20 | 0.06 | 898÷1632 | 54÷98 |
| K Cast iron | Gray cast iron GG20–GG30 | 13÷16 | 0.06 | 1061÷1306 | 64÷78 |
| N Copper and Al alloys | Cu, CuZn, Al, and alloys | 25÷28 | 0.08÷0.10 | 2040÷2285 | 163÷228 |
Drill sharpening
Sharpen the Ø3.9 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 Ø3.9 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 Ø3.9 mm drill bit
The maximum drilling depth is the flute length l2 = 43 mm minus the drill point length (approximately 1 mm). The effective usable depth is therefore approximately 42 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.
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Shipping
All orders are delivered by courier company GLS. For orders exceeding 369 PLN gross shipping is FREE
| Courier GLS | Przelew24 / Prepayment | 14,76 zł gross | Delivery time 1 working day |
| Courier GLS | Cash on delivery | 17,26 zł gross | Lead time 1 working day |
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