1/4" 3-Flute TiCN End Mill (metal)

ID: U02

Type: End Mill

The odd one out — a machinist’s end mill rather than a router bit. Made by Kyocera, sold under McMaster’s own part number. Three flutes, 30° helix, TiCN coated, centre cutting. It lives in the drawer for aluminium and fibreglass, and it is the wrong tool for every piece of wood in the shop.

Specifications

Property Value
Cutting diameter 0.250” (tolerance −0.0020” / +0.0000”)
Shank diameter 0.250”
Flutes 3, equal spacing
Cutting length 0.750”
Overall length 2.500”
Helix angle 30°
End type Square, centre cutting
Material Solid carbide
Coating TiCN (titanium carbon nitride)
Manufacturer Kyocera

Feeds & Speeds

For the X-Carve Pro and its 1.5 kW spindle. These match the presets stored on this tool in the Fusion hub library. Note the three-flute maths — chipload is feed divided by RPM and then by three, so the numbers look slower than a two-flute bit at the same chip thickness.

Material RPM Feed Chipload Plunge Depth of cut
Aluminium — adaptive 12,000 90 ipm 0.0025” 15 ipm to 0.250” at ~10% radial
Aluminium — slotting 10,000 60 ipm 0.0020” 12 ipm 0.030”
Brass / bronze 12,000 90 ipm 0.0025” 15 ipm 0.060”
Fibreglass / G10 12,000 75 ipm 0.0021” 15 ipm 0.060”
Plastic 10,000 100 ipm 0.0033” 20 ipm 0.060”

There is deliberately no wood preset. See below.

Notes

Not for wood. Three flutes means three small chip gullets, and wood chips are bulky and fibrous rather than the tight curls metal makes. They pack, heat builds, and the cut burns — which in maple leaves scorch you cannot sand out at depth. Router spirals are one or two flutes for exactly this reason. Use U01 or D01 instead.

Steel is out of reach on this machine, despite being what TiCN is really for. A 1/4” carbide end mill in mild steel wants roughly 250–350 SFM, or about 4,000–5,300 rpm. The X-Carve Pro’s spindle floor is 8,000 rpm, which works out to 523 SFM — far past where carbide survives in steel. Add no coolant and a machine built for wood, and ferrous work simply isn’t on the table.

Lubricate in aluminium. Aluminium has a chemical affinity for titanium-based coatings and will gall onto TiCN. A mist of WD-40 or denatured alcohol makes the difference between a clean wall and a welded edge. ZrN, DLC, or plain polished carbide would be the right coating here; this one works in aluminium in spite of its coating, not because of it.

Diameter runs undersize by design. The tolerance is −0.002” to 0.000”, so the cutter may be as small as 0.248”. On wood that is noise; on a precision aluminium fit it means parts come out up to 0.002” oversize on outside profiles. Measure a test cut and set a wear offset if the fit matters.

Maximum cut depth 0.750”. Same limit as D02 — it cannot cut through 3/4” stock.

Fibreglass and G10 are the one place the TiCN genuinely pays off, since both are abrasive enough to strip uncoated carbide. Run extraction and a respirator — the dust is an irritant and a lung hazard.

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