C8-303-08
3 Flute Standard Length C-2 Grade Carbide End Mill on 1/4" Dia. Shank
0.25-in Dia 3-Flute End Mill, 0.75-in LOC, 0.25-in Shank, 2.5-in OAL
OrderingC8-303-08·Uncoated·$73.75Change finish
All sizes on 1/4" shanks for strength — spiral routers for signmaking, engraving and CNC production.
- Every size (1/16"-1/4" cutting dia) built on a 1/4" shank for strength and to fit standard router collets
- C8 = up-shear spiral (chips lift out of the cut); CD8 = down-shear spiral router (presses the surface down for chip-free top faces on laminates and signs)
- 2 flute stub (C8-201) and standard (C8-203); 3 flute stub (C8-301) and standard (C8-303); down-shear CD8 in 2 flute stub (CD8-201) and regular (CD8-203)
- 30° helix, square end with chamfer option, C-2 grade carbide
- DLC coated versions of every C8 size (-DLC)
- Materials: wood, aluminum, copper, magnesium, brass, plastics, composites
- Tolerances: cutting dia +.000/-.002 (1/16"-1/4"), shank dia -.0001/-.0002, OAL +/-.060
From the RobbJack Applications Guide.
About this series
C8 C-2 Grade Carbide End Mills
2 and 3 flute C-2 grade end mills on 1/4" shanks for strength
The C8 series is a square-end, C-2 grade carbide end mill with a 30 degree helix, offered in 2 flute (C8-201/C8-203) and 3 flute (C8-301/C8-303) configurations in stub and standard lengths. All sizes are on 1/4" shanks for strength. Offered uncoated or with DLC coating. The same C8 tools also serve as 2 and 3 flute spiral routers for signmaking, engraving and CNC production in wood and plastics.
- Square end with 30 degree helix
- 2 and 3 flute, stub and standard lengths
- All sizes on 1/4" shanks for strength
- Uncoated or DLC coated
Aluminum, copper, magnesium, plastics, composites, brass, wood
Headline spec
C-2 grade, 30 degree helix, all sizes on 1/4" shanks
Best for
- Slotting and side milling
- Helical interpolation
- Spiral routing for signmaking, engraving and CNC production
Specifications
US machining terms with ISO 13399 codes.
- Cutting DiameterDC
- 0.25″
- Diameter ToleranceDC tol
- 0.0000/-0.0020
- Max Cutting DiameterDCX
- 0.25″
- Shank DiameterDMM
- 0.25″
- Length of Cut (LOC)APMX
- 0.75″
- Overall Length (OAL)OAL
- 2.5″
- Number of FlutesNOF
- 3
- Helix AngleFHA
- 30°
- Helix HandFHH
- Right-hand
- Cut Direction
- Right-hand cut
- End Type
- Square End
- Center Cutting
- Yes — plunges
- Shear Direction
- Up-shear
- Series
- C8-303 — 3 Flute Standard Length C-2 Grade Carbide End Mill on 1/4" Dia. Shank
Cuts these materials
Applications
See it run
Tolerances
| Type | Min | Max |
|---|---|---|
| Cutting Diameter | 0 | -0.002 |
| Length of Cut | +0.03 | 0 |
| Overall Length | +0.06 | -0.06 |
| Shank Diameter | -0.0001 | -0.0002 |
Choose the finish(2 options)
Compare →Each finish is a different part number and price.
Not sure? Compare tool coatings — or leave it uncoated, the most common choice for aluminum.
Part C8-303-08
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.
Uncoated
$73.75
C8-303-08
Starting speeds & feeds for the C8-303-08
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.
| Material | Operation | SFM | RPM | Feed (IPM) | Chip load / tooth | DOC (in) | WOC (in) |
|---|---|---|---|---|---|---|---|
| 6061(T4-T6) Aluminum | Roughing — full slot | 786 | 12,000 | 230.4 | .00640 | .2500 | .2500 |
| 6061(T4-T6) Aluminum | Finishing | 786 | 12,000 | 115.2 | .00320 | .2500 | .0125 |
| Free-Cutting Brass | Roughing — full slot | 750 | 11,460 | 110 | .00320 | .2500 | .2500 |
| Free-Cutting Brass | Finishing | 750 | 11,460 | 55 | .00160 | .2500 | .0125 |
| Acetal | Roughing — full slot | 786 | 12,000 | 230.4 | .00640 | .2500 | .2500 |
| Acetal | Finishing | 786 | 12,000 | 115.2 | .00320 | .2500 | .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 C8-303 series
Same series, different size — what changes from this tool is shown in red.
- C8-303-04$71.55Ø 0.125″LOC 0.5″3 FLOAL 2.5″
- C8-303-06$71.55Ø 0.1875″LOC 0.625″3 FLOAL 2.5″
- C8-201-02$51.15Ø 0.0625″2 FLLOC 0.125″OAL 2″
- C8-201-04$43.10Ø 0.125″2 FLLOC 0.25″OAL 2″
- C8-201-06$43.10Ø 0.1875″2 FLLOC 0.375″OAL 2″
- C8-201-08$43.102 FLLOC 0.5″OAL 2″Ø 0.25″
- C8-203-02$72.75Ø 0.0625″2 FLLOC 0.25″OAL 2.5″
- C8-203-04$71.55Ø 0.125″2 FLLOC 0.5″OAL 2.5″
- C8-203-06$71.55Ø 0.1875″2 FLLOC 0.625″OAL 2.5″
- C8-203-08$73.752 FLØ 0.25″LOC 0.75″OAL 2.5″
- C8-301-04$43.10Ø 0.125″LOC 0.25″OAL 2″3 FL
- C8-301-06$43.10Ø 0.1875″LOC 0.375″OAL 2″3 FL