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Metal drill bit 21.75 NWKc HSS DIN 345 Baildon
0375
Diameter (mm): 21,75301 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
€27.51 tax inc.
Net price: €22.37
Description
DIAMETER Ø21.75 mm
MORSE TAPER MT2
OVERALL LENGTH 248 mm
FLUTE LENGTH 150 mm
Technical specifications of the Ø21.75 mm drill bit
Twist drill with Morse taper shank
| TECHNICAL DATA | |
|---|---|
| Diameter | Ø21.75 NWKc HSS |
| Standard | DIN 345 |
| Drill type | NWKc — twist drill with taper shank |
| Material | HSS (high-speed steel) |
| Overall length l1 | 248 mm |
| Flute length l2 | 150 mm |
| Morse taper | MT2 |
| Point angle | 118° |
| Diameter tolerance | h8 |
| Cutting direction | Right-hand |
Ø21.75 mm HSS metal drill bit – Morse taper MT2
Product description and key benefits
The Ø21.75 mm twist drill with an MT2 shank offers a significant advantage over straight-shank drills: mounting stability increases with load. The self-holding Morse taper seats deeper in the spindle in proportion to the cutting torque. At a diameter of 21.75 mm, the Ø21.75 Morse taper drill provides vibration-free operation and uniform cutting edge wear even during intensive use.
Key benefits of the Ø21.75 mm metal drill bit
- Self-holding taper shank — MT2 transmits full torque to the cutting edges without intermediate components
- HSS with a hardness of 63–65 HRC — stable cutting of materials with tensile strengths up to 900 N/mm² without loss of sharpness
- Overall length of 248 mm — proportional to the drilling diameter — provides a balance between reach and rigidity
- General-purpose 118° geometry — suitable for most materials encountered in shop machining
- Sleeve compatibility — use on drilling machines with MT1 to MT3 spindles using reduction sleeves
- Repeated resharpening — HSS steel allows the cutting edge to be restored without loss of cutting properties
The Ø21.75 mm Morse taper drill is chosen for holes for bolted joints in machine components and steel structures. Maintenance departments use it to restore worn holes and drill new ones during assembly. Holes within tolerance class H12 (Ø21.750–Ø21.960 mm); tighter fits are achieved with a reamer.
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 Ø21.75 MM DRILL BIT:
| ✓ | MT2 → MT3 — for a spindle with an MT3 socket |
| ✓ | MT2 → MT4 — for a spindle with an MT4 socket |
| ✓ | MT2 drill drift — for removing the drill bit from the spindle |
Cutting data for the Ø21.75 mm drill bit according to ISO 513
Recommended machining conditions for a diameter of Ø21.75 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 | 0.20 | 161÷293 | 32÷59 |
| K Cast iron | Gray cast iron GG20–GG30 | 13÷16 | 0.20 | 190÷234 | 38÷47 |
| N Copper and Al alloys | Cu, CuZn, Al, and alloys | 25÷28 | 0.25÷0.32 | 366÷410 | 92÷131 |
Deep-hole drilling (over 3×D)
When drilling holes deeper than 65 mm (3×Ø21.75), periodically retract the drill every 1–1.5×D to remove chips. Use ample emulsion cooling (minimum concentration of 6–8%). Reduce the feed by 30–50% from nominal values.
Material compatibility of the Ø21.75 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 Ø21.75 mm drill bit
The HSS drill can be used for stainless steel with Vc reduced by 40% and ample cooling with a 8–10% emulsion. An HSSE (cobalt) drill of the same diameter is a more efficient option, retaining its hardness up to 650°C.
A pillar or box-column drilling machine with an MT2 spindle and a minimum power rating of 0.75–1.5 kW. Bench drilling machines with a drill chuck are not recommended — they cannot transmit the torque generated at a diameter of 21.75 mm.
It depends on the specific bolted joint. For metric coarse-thread bolts, the clearance hole diameter according to ISO 273 is 0.5–1 mm larger than the nominal thread diameter.
Product accessories
Long reduction sleeve MK1-2 PTPb 1762
Reference: 0000006908 In stock > 10 items
€15.79
€19.42 brutto
Reduction sleeve MK4 MK2 1751 PTPa DIN 228
Reference: 1181 In stock > 10 items
€15.79
€19.42 brutto
Reduction sleeve MK5 MK2 1751 PTPa DIN 228
Reference: 4910 In stock > 10 items
€22.37
€27.51 brutto
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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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