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Description
M12 20×14 mm counterbore with pilot
Type NWCa · DIN 373 · high-speed steel (HSS) · Artykuly Techniczne brand
Manufactured to DIN 373 20×14 mm counterbore with pilot (type NWCa) is used to counterbore holes for cylindrical screw heads M12 — including DIN 912 socket head cap screws. The pilot Ø14 mm centers the tool in the clearance hole, keeping the seat perpendicular to the axis and allowing full surface contact under the screw head. The counterbore made of steel HSS machines steel, aluminum, copper, and brass. A Polish product from the brand Artykuly Techniczne.
| Technical data | |
|---|---|
| Counterbore diameter D | 20 mm |
| Pilot diameter d₁ | 14 mm |
| Shank diameter d | 12.5 mm |
| Flute length l | 22 mm |
| Pilot length l₁ | 12 mm |
| Shank length l₂ | 40 mm |
| Overall length L | 100 mm |
| Number of cutting edges Z | 3 |
| For thread | M12 |
| Material | HSS |
| Standard | DIN 373 NWCa |
| Brand | Artykuly Techniczne |
| Country of manufacture | Poland |

Applications and workpiece materials
Applications and materials for the M12 counterbore
Typical applications:
| ✓ | Counterboring holes for cylindrical heads of M12 screws (DIN 912 / ISO 4762) |
| ✓ | Flat, perpendicular seat for the head and washer |
| ✓ | Spotfacing around the hole |
| ✓ | Use on CNC machines, drilling machines, and conventional machine tools |
Workpiece materials
Fixed pilot — centering and perpendicularity
Pilot Ø14 mm enters the clearance hole and guides the tool coaxially, keeping the counterbore perpendicular to the hole axis and allowing full surface contact under the screw head. Steel HSS retains its cutting hardness up to an operating temperature of approx. 600°C.
Cutting data
Guideline values for HSS · Ø20 mm
| Material group (ISO 513) | Vc [m/min] | fz [mm/tooth] | n [rpm] · Ø20 | f [mm/min] · Z=3 |
|---|---|---|---|---|
| PStructural and alloy steel | 5–25 | 0.03–0.10 | 80–400 | 7–120 |
| MStainless steel | 6–15 | 0.03–0.06 | 95–240 | 9–45 |
| KCast iron | 10–20 | 0.08–0.12 | 160–320 | 40–110 |
| NNonferrous metals (Al, Cu, brass) | 15–80 | 0.06–0.14 | 240–1 250 | 45–530 |
| SDifficult-to-machine alloys and titanium | 8 | 0.04 | ≈130 | ≈15 |
Vc — cutting speed, fz — feed per tooth. Columns n and f calculated for D = 20 mm and Z = 3 (rounded). For tools made of steel HSS-E the cutting parameters can be increased by 25%.
How n and f were calculated (Ø20, Z = 3)
Spindle speed n = (Vc × 1000) ÷ (π × D), feed rate per minute f = fz × Z × n. Example for steel (Vc = 20, fz = 0.1): n = 20 000 ÷ 62.8 ≈ 320 rpm, f = 0.1 × 3 × 320 ≈ 95 mm/min. Start at the lower end of the range and adjust according to the material and clamping rigidity.
Tips and limitations
How to extend tool life
HSS limitations
The tool is not intended for hardened steels above 45 HRC. For stainless and alloy steels, reduce the speed and use coolant — overheating accelerates cutting edge wear. Make sure the clearance hole diameter matches the pilot Ø14 mm.
Frequently asked questions
The M12 counterbore produces a flat seat for cylindrical heads of M12 screws, including DIN 912 / ISO 4762 socket head cap screws. The Ø14 mm pilot enters the clearance hole for M12 and centers the tool. The Ø20 mm counterbore diameter accommodates an M12 socket head cap screw head (Ø18 mm per DIN 912) with a small clearance.
Yes — the tool has a Ø12.5 mm straight shank and fits drill chucks and collets. However, at a diameter of Ø20 mm, low speeds (approx. 80–400 rpm for steel) and rigid workpiece clamping are recommended — preferably a benchtop or pillar drill rather than a handheld drill.
Yes — for ISO M materials (stainless steel), operate at a reduced cutting speed (Vc approx. 6–15 m/min, or approx. 95–240 rpm for Ø20 mm) and use coolant to limit work hardening and overheating. Do not use the tool on hardened steels above 45 HRC.
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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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