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End MillMade in USA

NS-403-16

4 Flute Variable Helix X-Long Len. Solid Carbide End Mill for Steels & Cast Iron

0.5-in Dia 4-Flute End Mill, 1.5-in LOC, 0.5-in Shank, 4-in OAL, 0.01-in Chamfer with Weldon Flats

OrderingNS-403-16·Aluminum Titanium Nitride (AlTiN)·$247.80Change finish

4 Flute Variable Helix X-Long Len. Solid Carbide End Mill for Steels & Cast Iron — NS-403-16
Series photo — representative of the NS-403 family
OAL 4″Flute 1.5″Shank Ø0.5″Cutter Ø0.5″Square
Scaled drawing — true to this tool's dimensions (inch)
Speeds & FeedsDialed to this exact tool — free
Free CAD & DataSTEP 3DDXF 2DISO CSVCAM library
NS Series recommended engagement diagrams: slotting at 1 x diameter width and .5 x diameter depth, profiling at .5 x diameter radial width and 1 x diameter axial depth

4-flute variable-helix Tuffy grade end mills for cast iron and steels to 40 HRc — stub, standard, and long lengths, AlTiN coated, with optional flats for high-torque cuts.

  • 4 flute, variable helix — the variable pitch damps harmonics for stable cuts in cast iron and steel up to 40 HRc hardness
  • Three lengths per diameter: NS-401 stub, NS-402 standard, NS-403 long (e.g. 1/2": 3/4", 1-1/8", and 1-1/2" flute lengths)
  • Inch sizes 3/16"–1"; metric MNS line runs 4–20 mm
  • Every tool AlTiN (aluminum titanium nitride) coated, in flats (-FL) and no-flats versions — 'Slippage? Tool Holder — Add Flats!' for high-torque cuts
  • Protective corner chamfer on every size, .008 to .02 by diameter (metric 0.2–0.5 mm)
  • Guide engagement guidance: slot at 1 × diameter width and .5 × diameter depth; profile at .5 × diameter radial width and 1 × diameter axial depth
  • Applications: slotting, side milling, helical interpolation, ramping, high-performance roughing, semi-finishing, and finishing — dry or wet
  • Tolerances: NS cutting dia −.001/−.002, shank −.0001/−.0002, flute length +.060/−.000; MNS cutting dia −0.025/−0.050 mm, shank −0.002/−0.005 mm

From the RobbJack Applications Guide.

About this series

NS / MNS Tuffy Grade Carbide End Mills

Variable-helix 4-flute tools for titanium, steel & high-temp alloys

The NS Series (and metric MNS Series) are 4-flute Tuffy Grade carbide end mills with variable helix geometry, AlTiN coated, built for machining titanium, steel and high-temp alloys. Offered in stub (NS-401), standard (NS-402) and long (NS-403) lengths, with or without flats for high-torque cuts. Featured application: 6Al4V titanium flap track for airplane wings.

  • 4 flute, square end
  • Variable helix geometry
  • AlTiN coated
  • Available with flats for high-torque cuts (add -FL); flats eliminate tool-holder slippage
  • Offered in stub, standard and long lengths
  • Inch (NS) and metric (MNS) sizes

Cast iron, steel, and materials up to 40 HRc hardness; titanium and high-temp alloys. Applications: slotting, side milling, helical interpolation, ramping, high-performance roughing, semi-finishing and finishing (dry or wet).

Headline spec

4-flute variable-helix Tuffy Grade carbide, AlTiN coated

Best for

  • Titanium machining (e.g. 6Al4V)
  • Steel and high-temp alloys
  • Slotting and profile milling
  • High-performance roughing and finishing

Specifications

US machining terms with ISO 13399 codes.

Cutting DiameterDC
0.5″
Diameter ToleranceDC tol
0.0010/0.0000
Max Cutting DiameterDCX
0.501″
Shank DiameterDMM
0.5″
Length of Cut (LOC)APMX
1.5″
Overall Length (OAL)OAL
4″
Corner ChamferCHW
0.01″
Chamfer AngleKCH
45°
Number of FlutesNOF
4
Helix AngleFHA
Variable
Helix HandFHH
Right-hand
Cut Direction
Right-hand cut
End Type
Chamfer
Center Cutting
Yes — plunges
Shank Flats
Available (-FL)
Series
NS-403 — 4 Flute Variable Helix X-Long Len. Solid Carbide End Mill for Steels & Cast Iron

Cuts these materials

Cast IronSteelHardened 30–40 HRc

Applications

SlottingSide MillingHelical InterpolationRampingHigh PerformanceRoughingSemi-FinishingFinishingDryWetCold AirSpray Mist

See it run

Tolerances

TypeMinMax
Cutting Diameter+0.0010
Length of Cut+0.060
Overall Length+0.06-0.06
Shank Diameter-0.0001-0.0002

Choose the finish(2 options)

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Each finish is a different part number and price.

AlTiN · your price$247.80

Part NS-403-16

Made & shipped in the USA · lead time confirmed at order. Test this tool in your spindle at retail, or get it through your RobbJack distributor.

Performance guaranteed. Run it against the tool you use today — if it doesn't beat it, we'll make it right.

Adds NS-403-16 · Aluminum Titanium Nitride (AlTiN) · $247.80

Calculate Speeds & Feeds
CADDXF·STEP
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Download ISO 13399 data (.csv)

Proven in the field

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AlTiN

$247.80

NS-403-16

Starting speeds & feeds for the NS-403-16

Dial in for your machine →

RobbJack's tested starting numbers for this exact tool, from the same engine and the same default machine as the calculator: a 12,000 RPM / 400 IPM / 30 HP machining center, rigid setup, full-depth cut. A faster or smaller spindle changes the RPM and feed — enter yours in the calculator and it re-governs every number.

Starting speeds and feeds for RobbJack NS-403-16
MaterialOperationSFMRPMFeed (IPM)Chip load / toothDOC (in)WOC (in)
Gray IronRoughing — full slot5254,01151.3.00320.3500.5000
Gray IronFinishing5254,01151.3.00320.7500.0125
4140 SteelRoughing — full slot4003,05624.4.00200.3500.5000
4140 SteelFinishing4003,05624.4.00200.7500.0125
P20 (30-40hrc) Tool SteelRoughing — full slot4153,17125.4.00200.3500.5000
P20 (30-40hrc) Tool SteelFinishing4153,17125.4.00200.7500.0125

Read before you run

Recommendations are computed starting points based on typical conditions — not guarantees of performance, tool life, or fitness for your application. Machining involves inherent risk: you are solely responsible for safe operation, for verifying every parameter against your machine, spindle, toolholding, workholding, and guarding limits, and for proving all parameters on a test cut before production. RobbJack Corporation assumes no liability for tool breakage, machine damage, scrapped parts, production loss, or personal injury arising from use of these recommendations. By using this calculator you accept RobbJack's Terms & Conditions.

More in the NS-403 series

Same series, different size — what changes from this tool is shown in red.