H7/k6 fit: locational transition fit
Accurate location where a small interference is acceptable: bearing inner rings on shafts with normal loads, gears and couplings secured with a key.
| Nominal size (mm) | Hole H7 (µm) | Shaft k6 (µm) | Max. clearance (µm) | Min. clearance (µm) |
|---|---|---|---|---|
| 1–3 | +10 / 0 | +6 / 0 | +10 | -6 |
| >3–6 | +12 / 0 | +9 / +1 | +11 | -9 |
| >6–10 | +15 / 0 | +10 / +1 | +14 | -10 |
| >10–18 | +18 / 0 | +12 / +1 | +17 | -12 |
| >18–30 | +21 / 0 | +15 / +2 | +19 | -15 |
| >30–50 | +25 / 0 | +18 / +2 | +23 | -18 |
| >50–80 | +30 / 0 | +21 / +2 | +28 | -21 |
| >80–120 | +35 / 0 | +25 / +3 | +32 | -25 |
Negative clearance means interference. Example: a Ø20 H7/k6 fit has a hole of 20.000–20.021 mm and a shaft of 20.002–20.015 mm.
On the drawing
Write the fit after the size: Ø20 H7 on the hole and Ø20 k6 on the shaft. Shops ream H7 holes routinely; tight shaft grades usually need fine turning or grinding.
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