FM-305-12-120
3 Flute Aluminum Chatter-Free Extra Long High Performance Carbide End Mill
0.375-in Dia 3-Flute End Mill, 0.375-in LOC, 0.375-in Shank, 4-in OAL, 0.12-in CR, 2.125-in Reach
OrderingFM-305-12-120·Uncoated·$194.75Change finish
2 and 3 flute chatter-reduction end mills with necked reach and radii — the tool that took an automotive aluminum part from 41 hours to 1 hour, in short to extra-long reaches.
- 2 flute (FM-201–205) and 3 flute (FM-301–305), 40° helix, with Feather Blend, necked reach, and Mirror Edge chatter reduction
- Four reach lengths per diameter — short, medium, long, and extra-long (e.g. 1/4" tools reach 5/8" to 1-1/16"+ on a 3" OAL); other reach lengths available upon request
- Inch sizes 1/4"–1"; metric MFM line (2 & 3 flute, 201–205/301–305) runs 6–25 mm
- Corner options: square end, radii of .03", .06", .09" (plus .12" on larger sizes), and ball end (-BN); available uncoated or DLC coated
- Guide case story: an automotive aluminum part went from a 41-hour cycle time to 1 hour with the FM Series — no chatter and superfast feed rates at 450 ipm in an aluminum extrusion
- Guide speeds & feeds run at Max RPM with chip loads from .0040 (1/4") to .0160 (1") per tooth in 6061/7075/2024, at typical Z-depths of .150"–.250"
- Guide rule: Z-depth per pass should be deeper than the corner radius to help reduce chatter
- Applications: slotting, side milling, helical interpolation, ramping, high-performance 3-D (2-flute), roughing, semi-finishing, finishing — wet; materials: aluminum, copper, magnesium, brass
- h4 shank tolerance on all tools — up to 150% more gripping force to eliminate tool pull-out
- Series tolerances: cutting dia −.0007/−.0015 (3-flute pages list −.001/−.0015), shank −.0001/−.0002, flute length +.060/−.000, OAL ±.060
From the RobbJack Applications Guide.
About this series
FM / MFM Aluminum Chatter-Free End Mills
High-performance necked-reach aluminum, chatter-free.
Necked-reach solid carbide end mills tuned for clean, chatter-free aluminum cutting at performance feed rates — the high-performance sibling to the high-velocity FMHV line.
Best for
- Aluminum finishing
- Necked-reach work
- Production volume
Specifications
US machining terms with ISO 13399 codes.
- Cutting DiameterDC
- 0.375″
- Diameter ToleranceDC tol
- -0.0010/-0.0015
- Max Cutting DiameterDCX
- 0.374″
- Shank DiameterDMM
- 0.375″
- Length of Cut (LOC)APMX
- 0.375″
- Reach (LBS)SDL
- 2.125″
- Neck DiameterND
- 0.3563″
- Overall Length (OAL)OAL
- 4″
- Corner RadiusRE
- 0.12″
- Number of FlutesNOF
- 3
- Helix AngleFHA
- 40°
- Helix HandFHH
- Right-hand
- Cut Direction
- Right-hand cut
- Blend Angle (neck→shank)
- 15°
- Feather Blend
- 10°
- End Type
- Corner Radius
- Center Cutting
- Yes — plunges
- Series
- FM-305 — 3 Flute Aluminum Chatter-Free Extra Long High Performance Carbide End Mill
Cuts these materials
Applications
Features
See it run
Tolerances
| Type | Min | Max |
|---|---|---|
| Cutting Diameter | -0.001 | -0.0015 |
| Length of Cut | +0.06 | 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 FM-305-12-120
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
$194.75
FM-305-12-120
Starting speeds & feeds for the FM-305-12-120
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 | 1,179 | 12,000 | 151.2 | .00420 | .1500 | .3750 |
| 6061(T4-T6) Aluminum | Finishing | 1,179 | 12,000 | 75.6 | .00210 | .1500 | .0750 |
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 FM-305 series
Same series, different size — what changes from this tool is shown in red.
- FM-305-08$114.65Ø 0.25″LOC 0.25″reach 1.5″OAL 3″
- FM-305-08-030$124.80Ø 0.25″LOC 0.25″CR 0.03″reach 1.5″
- FM-305-08-060$124.80Ø 0.25″LOC 0.25″CR 0.06″reach 1.5″
- FM-305-08-090$127.50Ø 0.25″LOC 0.25″CR 0.09″reach 1.5″
- FM-305-08-BN$130.25Ø 0.25″LOC 0.25″CR 0.125″reach 1.5″
- FM-305-10$148.40Ø 0.3125″LOC 0.3125″reach 1.625″OAL 3.125″
- FM-305-10-030$153.65Ø 0.3125″LOC 0.3125″CR 0.03″reach 1.625″
- FM-305-10-060$153.65Ø 0.3125″LOC 0.3125″CR 0.06″reach 1.625″
- FM-305-10-090$157.25Ø 0.3125″LOC 0.3125″CR 0.09″reach 1.625″
- FM-305-10-120$157.25Ø 0.3125″LOC 0.3125″reach 1.625″OAL 3.125″
- FM-305-10-BN$161.00Ø 0.3125″LOC 0.3125″CR 0.1563″reach 1.625″
- FM-305-12$187.50Ø 0.375″3 FLLOC 0.375″reach 2.125″