Length, bore, and the model list that makes both mean something
Replacement mower blades, compared
A rotary mower blade is a steel bar bolted to a vertical shaft, and it is the one part of a mower that is guaranteed to need replacing. Three figures decide whether a blade fits, and a listing that gives two of the three is a listing that cannot be trusted. The length is the first: it matches the cutting width, so a 43 cm mower takes a 43 cm blade, and the corpus shows 30, 32, 38, 43 and 53 cm on ordinary domestic machines. The bore is the hole in the middle, and it is where most mistakes happen — the same length exists with different centre holes, and a blade that is a millimetre out will not sit on the boss. The fixing is the third: a single central bolt on most, a star boss or a pair of offset holes on others, and adapters are sold precisely because the pattern is not standard. Which is why the fits column carries the weight on this shelf. Good listings name machines — Makita DLM382, Gardena PowerMax 32, Scheppach petrol 530 mm — and bad ones say « universal », which for a blade means the buyer measures. The material is usually hardened steel and occasionally coated; it decides how long the edge lasts rather than whether the blade fits. And the pack, because blades are sold singly for rotary mowers and in tens or thirties for robots, which is the clearest sign that a listing has wandered onto the wrong shelf. We compare length, bore, fixing, material, fits and pack.
