Metric End Mill Sizes: 0.7mm to 3.0mm Selection Guide
By Premium CNC & Router Bits for Precision Cutting | Published: 2026-11-02
Category: How-to Guides
Pick the right small metric CNC bit by matching tip shape, flute length and shank to your cut. A step-by-step process for 0.7mm to 3.0mm end mills.
Quick answer
Choose your metric end mill by the shape of the cut first, then by the depth you need to reach. Use a ball end mill for curved 2D and 3D contours, a square end mill for flat-bottom slots and pockets, and a deep-cut square tool when the cavity is deeper than a standard flute length can reach.
Why tip shape comes before size
Two bits with the same tip diameter can produce very different results because the tip geometry controls the floor and wall of the cut. A ball end mill leaves a rounded floor and is the correct choice for curved details, slopes and 3D contours. A square end mill leaves a flat floor and sharp internal corners, which is what you want for slots and pockets.
Size then sets the smallest feature you can machine and the load on the tool. A 0.7mm ball end mill can reach fine detail but removes very little material per pass, while a 3.0mm tool is more rigid and clears material faster. If you need a specific radius or corner, work back from that feature rather than starting with the largest bit that fits.
Flute length is a reach decision, not a stiffness bonus
A long flute lets the tool reach down into a cavity, but it also puts more unsupported cutting edge below the collet. The 3.0mm deep cut square end mill carries a 20mm flute length on a 50mm overall length, so it can reach into deep pockets that a short-flute tool cannot. Treat that reach as a job-specific tool: use it where depth is the problem, and use a shorter-flute bit for shallow work where rigidity matters more.
The catalog does not list helix angle, coating or maximum depth of cut for these tools, so do not assume a feed and speed recipe from the size alone. Start conservative and adjust from the sound and chips you observe.
Shank size and runout on small bits
All three tools in this size range use a 3mm shank, which keeps them compatible with the same small collet. Small-diameter tools are sensitive to runout, so clean the collet and nut and seat the bit fully before tightening. A bit that looks correct but chatters is often sitting slightly off-axis rather than cutting the wrong geometry.
How to choose a small metric end mill, step by step
- 1. Sketch the feature you need to cut: Identify whether the cut has a flat floor, a rounded floor or a curved wall, and note the smallest internal radius. Common mistake: choosing a square end mill for a curved 3D contour, which leaves steps instead of a smooth surface. If the drawing shows a radius, you need a ball end mill.
- 2. Match tip shape to the feature: Use a ball end mill for rounded slots, slopes and 2D or 3D contours. Use a square end mill for flat-bottom slots and pockets with sharp corners. Checkpoint: confirm the tip shape before comparing diameters.
- 3. Measure the depth you must reach: Compare the required cut depth with the flute length, not the overall length. A 20mm flute length on the 3.0mm deep cut square end mill reaches far deeper than a short-flute bit. Common mistake: assuming a long overall length means long reach, when the flutes may be much shorter. If the pocket is deeper than the flute length, step up to a long-flute tool.
- 4. Pick the smallest tip that clears the detail: Choose 0.7mm for the finest curved detail, 1.8mm for mid-size rounded features, and 3.0mm when you need a flat floor or more rigidity. Common mistake: going straight to the smallest bit for every job, which slows the cut and increases the chance of breakage.
- 5. Confirm the shank and collet: All three tools here use a 3mm shank, so check that your collet matches and that the bit seats fully. Clean the collet taper and nut before tightening. Checkpoint: spin the tool by hand and look for visible runout before cutting. A clean, fully seated 3mm shank protects small bits from chatter.
- 6. Test the cut and adjust: Make a light first pass in scrap of the same material and listen for chatter. Because the catalog does not supply feed and speed data for these tools, start conservative and increase only when the cut is stable. Common mistake: copying a recipe from a different bit size or material.
Metric end mills in this size range
- 3.0mm Metric Deep Cut Square End Mill 20mm cut length: 3.0mm square end mill with a 20mm flute length, 3mm shank and 50mm overall length. The long flute gives you reach for deep slots and pockets where a standard-length bit bottoms out.
3.0mm Metric Deep Cut Square End Mill 20mm cut length - 0.7mm Metric Ball End Mill: 0.7mm solid carbide 2-flute ball end mill with a 3mm shank and 38mm overall length. The tiny ball tip is suited to fine curved detail and 3D contouring in wood, plastic and metal.
0.7mm Metric Ball End Mill - 1.8mm Metric Ball End Mill: 1.8mm solid carbide 2-flute ball end mill with a 5.4mm flute length, 3mm shank and 38mm overall length. The mid-size ball tip balances detail and rigidity for rounded slots and slopes that are too large for the 0.7mm tool.
