Robot mower blade replacement: every published interval, the one torque spec, and what genuine blades actually buy you

The torque spec: 1 N·m, and only three brands publish it

If you want a number for how tight the blade screws go, there is one, and it’s 1 N·m. We verified it across three unrelated manufacturers on 2026-08-19:

Segway’s i-series manual (p.44) puts it plainly: “Fasten the new blades and screws (Torque: 1 N·m). Make sure the blades can pivot freely.” The same figure appears in the H-series and X3-series manuals, and Navimow’s UK distributor repeats it as “Torque to 1 N·m using your screwdriver.” eufy’s E15/E18 manual (p.26) independently says “ensure the new blades and screws are securely fastened (Torque: 1 N·m).” Sunseeker’s X3 manual is the most precise of the three, giving a tolerance band and a consequence: “Replace the screws with a standard torque of 1.0+0.2 N.m. Incorrect torque may lead to avoidable issues.”

Three brands landing on the same figure is about as close to an industry convention as this category gets. It is not, however, a spec for your mower unless your manual says so — if Husqvarna or Worx built your machine, they publish no number at all.

Don’t reach for a power tool. Navimow’s warning block is explicit: “DO NOT use an electrical screwdriver to install or loosen the cutting disc.” Roborock’s manual gives the same instruction. At 1 N·m — roughly the force of a firm turn between thumb and forefinger on a small screwdriver — a cordless driver will blow straight past it.

One thing worth knowing before you decide you’ve under-tightened: on pivoting-blade mowers the blades are meant to feel loose. Navimow’s manual addresses it directly — “After fastening the blades and screws the blades will still seem loose. This is normal as the blades need to spin during mowing” — because the cutting edge is thrown out by centrifugal force once the disc spins. Husqvarna frames the same thing as a feature: blades should spin freely when correctly installed, “a safety feature, not a defect.”

For everyone else, the qualitative spec is consistent across every manual we read: firm, but the blade must still pivot freely. Worx’s wording is “Firmly screw on the new blades” plus “make sure the blade is able to spin freely.” That’s the whole instruction.

Every published replacement interval we could verify

The intervals are all over the place, and they’re split between calendar-based and hours-based schemes. Everything below is from an official manual or support article, checked today:

Roughly six weeks is the centre of gravity, and the outliers are explicable: Husqvarna’s EdgeCut blades last longer because they only run on the edge pass, and the long-life SKUs (Husqvarna Endurance, Worx WA0789) trade cost for interval.

Two honesty notes. Segway states two different intervals for the same machine — the X3 manual says 1–2 months while its support article says every 80 working hours. They’re not incompatible (80 hours is roughly one to two months at typical duty), but Segway never reconciles them. Worx does the same: its manuals say a blade lasts “up to 2 months when it is programmed to mow every day,” while the long-life product page markets 3–4 months. When a manual and a product page disagree, believe the manual.

Mammotion deserves credit for the most honest number in the category. It publishes “Flip the blades at 50 hours, replace at 150 hours” — and then names the test conditions: “The grass species tested in this dataset is Zoysia grass.” Nobody else tells you what their interval was measured on. (Mammotion’s LUBA 3 AWD blade-maintenance guides, incidentally, are still marked “Coming Soon” as of this week — the blade guard bracket and cutting disc assembly pages have been unpublished for months.)

The rule every manufacturer agrees on: replace the screws

This is the one point of total consensus across every brand we checked, and it’s the one owners skip most often.

• Husqvarna: “Replace screws each time you change blades. Reusing screws may lead to blades coming loose during operation.”
• Segway: “DO NOT reuse the screws. Doing so can cause serious injury.”
• eufy: “DO NOT reuse screws. Used screws may wear out quickly, causing the blade to loosen, which can lead to serious injuries.”
• Roborock: “Never reuse the screws — doing so may lead to blade detachment and serious injury.”
• Worx: “Always use new screws when fitting blades. This is important to ensure blade retention and balance the blade turning disc. Failure to use new screws could cause serious injury.”
• Gardena: “You must replace the screws when you replace the blades. The used screws can wear quickly and make the blade come loose.”

Six manufacturers, independently, in almost identical language. A blade kit without screws is an incomplete kit. Worx’s WA0789 ships 6 blades with 6 screws and WA0190 ships 12 with 12; Husqvarna sells screws with its Enhance HSS packs. If a cheap third-party pack doesn’t include them, you’re either buying screws separately or ignoring every manufacturer in the category.

Balance: why replacing one blade isn’t a repair

The second universal rule is that blades go in sets. Husqvarna: “All 3 blades and screws must be replaced at the same time to get a balanced cutting system.” Worx: “Whenever you replace one blade, be sure to replace ALL the blades.” eufy and Dreame say the same for their three-blade discs.

Husqvarna also names the failure mode, which is the part worth internalising: “Avoid mixing different blade types or combining new and old blades. This can cause cutting disc imbalance, resulting in noise or vibrations.” A wobbling disc is the thing that chews bearings and loosens fasteners. If your mower has got noisier since its last blade change, mismatched blades are the first thing to check.

Dreame’s A1 is the interesting exception to the whole torque discussion: it uses a snap-in receptacle rather than screws — “Press the button under the blade disc and align the hole of the receptacle with the shaft” — which sidesteps fastener torque entirely. Dreame still tells you to replace the receptacles along with the blades, “because worn receptacles can make the blades loose and cause injury.” Same physics, different hardware.

Genuine vs third-party: what the documents actually say

Every manufacturer wants you buying their blades, so read the language for what it’s conditioning rather than what it’s asserting.

The strongest statement is Husqvarna’s, and it’s a safety conditional rather than a warranty threat: “Husqvarna can only guarantee safety if you use Husqvarna original blades with the embossed crowned H-mark logotype.” Gardena — same corporate group — uses word-for-word the same construction. Stiga’s is the clearest warranty exclusion: the warranty doesn’t cover damage resulting from “Use of non-genuine spare parts (adaptable parts)” or “Use of accessories not supplied or approved by the manufacturer (e.g. cutting devices).” Worx makes genuine parts an explicit warranty condition — cover applies only where “Only genuine Worx Landroid Vision® accessories and parts have been used” — and Segway, Ecovacs, Dreame and Ambrogio all say some version of “original blades only.”

But note what’s excluded anyway. Husqvarna: “The blades and wheels are seen as disposable and are not covered by the warranty.” Worx excludes “accessories such as blades and wheels” from its 3-year cover. So third-party blades don’t cost you blade warranty — there wasn’t any. What’s at risk is cover on everything the blades can damage: Husqvarna’s exclusion is for “Damage caused by not using Husqvarna original spare parts and accessories, such as blades and installation material.”

Is there a technical basis, or is it upselling? There is a real one, and it isn’t the steel. Robot mowers are certified to IEC 60335-2-107 / EN 50636-2-107, the safety standard for robotic battery-powered mowers, which defines “blade” as the everyday term for “cutting means.” The full text is paywalled (CHF 405 from the IEC), but the free official preview shows the table of contents — and it includes Annex AA, a normative “Calculation of kinetic energy of pivoting cutting elements,” complete with a figure for measuring the blade’s “reckonable length.” The standard also carries normative annexes for thrown-object testing and a foot-probe test using a probe shaped like a standing child’s foot.

That’s the honest technical answer: blade mass and geometry are compliance inputs. A third-party blade with different mass or length isn’t a like-for-like swap in the terms the certification was granted on, even if it bolts up fine. We found no torque requirement in the standard — don’t let anyone tell you 1 N·m is mandated; it’s the manufacturers’ own figure.

We also checked whether regulators have ever acted on this. Searching the CPSC recall database, there is no recall involving aftermarket or third-party robot mower blades — a clean negative. The one blade-related robot mower recall on file is from 2008: LawnBott models LB2000–LB3200, recalled because “the cutting blades continue to rotate when the mower is lifted from the ground” and a foot could reach past the shield. That’s a machine-design fault, not a parts fault.

What blades cost

Verified live today, and deliberately limited to prices we could actually load — Amazon, Walmart and several aftermarket sellers block automated checks, so we’re not quoting numbers we couldn’t confirm:

• Husqvarna Endurance Blades, 6-pack, part 595 08 44-11 — $24.99, in stock at Robotic Mower Supply.
• Husqvarna Automower Enhance HSS Blades, 45-pack — $209.99 at TurfCloud’s store (~$4.67 a blade, screws included).
• Worx WA0789 long-life, 6 blades + 6 screws — $29.99 ($5.00/blade).
• Worx WA0190, 12 blades + 12 screws — $34.99 ($2.92/blade).
• Mammotion Endurance Replacement Blades, 24-pack — $49.00 ($2.04/blade), stainless, compatible across the LUBA and YUKA lines.

At two to five dollars a blade, genuine blades are not where robot mower ownership gets expensive. A full set for a three-blade machine, four times a season, is under $30 a year for most owners. That’s the practical argument against third-party blades: the saving is a few dollars a season, and the thing you’re saving it on is the only part of the machine designed to cut.

One correction worth carrying

You may run into a widely-quoted line that “Husqvarna does not recommend sharpening a blade — a new blade is precision designed and manufactured for excellent quality of cut and balance.” That quote is real, but it is not about Automower. It lives in Husqvarna’s general support FAQ under the question “Can I sharpen the blade on my walk behind lawn mower?” — a page first published in 2006 — and it goes on to explain how to sharpen one. Husqvarna publishes no sharpening guidance for robot mower blades at all.

The reason not to sharpen a robot mower blade doesn’t need a quote: these are stamped razor-thin pivoting blades that cost about two dollars and are balanced in sets of three. There’s nothing there to sharpen.

The routine

1. Find your interval in the table above — and if your mower counts hours, use hours.
2. Buy blades and screws together, one set per disc, all replaced at once.
3. Turn the mower off at the main switch, glove up, and turn it over.
4. Fit new blades with new screws. If your brand publishes a torque, it’s 1 N·m (Sunseeker allows +0.2). If it doesn’t: firm by hand, hand-driver only, no power tools.
5. Confirm every blade pivots freely. Loose-feeling is correct; seized is not.
6. Reset the blade timer if your app has one — Automower Connect does.

If the disc is noisy or vibrating after a change, you’ve almost certainly got mixed blade types or a reused screw. Take it apart and do the set properly.