The Perils of a Robot Lawnmower with No Perimeter Wire

I get a lot of questions directed to me about installation of a perimeter wire and the reason why all of the major brands (Bosch, Worx, Husqvarna, Flymo, Gardena, etc.) rely on this technology. The fact of the matter is it wasn't always the case, and it's also still possible to buy robot lawnmowers that don't rely on a perimeter wire to delimit the mowing area.

But, is that a good thing?

Let's look at a few of the options available to manufactures using today's technology.

Robot Mower with Sensors

Mowers like the LawnBott Spyder, for example, don't use a perimeter wire. In fact, according to the LawnBotts web site, this is hailed as "a new beginning for robotic lawnmowers."

However, I would dispute this, as I have a friend with a sensor-based mower that pre-dates my own Husqvarna/Gardena R40Li, which he inherited from a family member who I assume had upgraded to a better version.

A quick question and answer session later revealed that while there are issues with sensor based mowers, largely my friend was well satisfied with the performance of the mower. However, there were a few basic flaws.

The first is that without a ground wire, the mower has to way to find it's way "home" for recharging. Therefore, it has to be charged indoors.

In fact, the mower has no way of knowing where it is, or where it has been; it's a dumb mechanical device, with none of the intelligence built into more modern models.

The way that they work is simple: they have sensors facing down which detect grass, and bump sensors to prevent chopping up the family pet. The lawn sensors rely on moisture detection, and the ability to tell the difference between mildly damp grass and, say, concrete or gravel.

My own feeling is that this is fine for most regularly shaped, enclosed areas, but as soon as you add a pond, or something that can become overgrown and poses a threat to the mower -- either damaging it, or allowing it to 'escape' -- I wouldn't feel personally comfortable relying on a few sensors to keep it in check.

Then there's the security aspect: one can imagine that stealing a plug-in to recharge mower that doesn't rely on a coded perimeter wire signal is a bit more of an attractive option than one which relies on a fully wired-in installation.

However, there are other options.

Robot Mower with a Virtual Perimeter Wire

These fall into two categories:

• Roomba style transmitters;
• Remote control / smartphone control plus learning.

In 2015, iRobot secured the go-ahead from the FCC to develop and deploy the same kind of technology that is used for their Roomba robot vacuum cleaners for outside use. This would allow them to create an iRobot lawnmower. Because it is guided by localised positioning using radio waves, however, it sparked anger amongst radio astronomers.

Of course, since then, their flagship technology has moved up a gear, and now uses all kinds of visual cues and smartphone interaction to "map and adapt" to the task in hand, rather than using navigation pods. Perhaps this move away from the older technology explains why we haven't seen the iRobot lawnmower as yet.

That leaves remote control or smartphone control plus learning. In fact, SmartMow has pinned their hopes on this approach, and have patented "Virtual Boundary Technology" which they explain as the ability to "Just walk SmartMow around the perimeter of your yard".

I'm actually looking forward to reviewing the SmartMow, because it appeals to me on a number of levels, including some exciting technology for connecting to it via a web portal.

The idea seems to be that the mower will learn where the perimeter is by being "shown" it, and then left to its own devices. Of course, the mower also has the regular sensors to allow it to avoid unexpected objects, but because the solution is software rather than hardware, my reservations re: ponds and robots going mad (as in the movie Short Circuit) still hold.

Robot Mower with GPS

Everything from farm machinery to those massive machines that rake the pistes in the Alps use GPS, so why not home robot mowers?

Husqvarna's Automower does just that. It even has its own app to help you fully take advantage of the set and forget nature of automatic robot lawn mowing.

(By the way, these are at the expensive end of Husqvarna's range -- the affordable models still use a perimeter wire... as do the ones with GPS!)

But here's the thing; it still uses a guide wire, presumably for security reasons.

In fact, aside from this experimental design from 2016, I was unable to find an example of a commercial automatic lawn mower that relied 100% on GPS for its perimeter detection and mowing capability.

So, all in all, it seems as if the good old perimeter wire is here to stay: sometimes lo-tech is really the best tech! If you're still wavering, read our Perimeter Wire Tips & Tricks Post; I'm pretty sure you'll agree that it's still the easiest, safest and most reliable method of keeping your robotic mower in check.

Robot Lawn Mower Perimeter Wire Tips & Tricks

Based on the last few years of robotic lawn mower ownership, I have a number of trips, tricks and tools for setting up and maintaining my robot lawn mower perimeter wire, as well as some recommended products.

A key point to remember is that while some of these parts are compatible (pegs and connectors, for example) many of them are not. At the same time, for some of the more basic installation and maintenance tasks (extending the perimeter wire, for example) regular off-the-shelf third party components can be used.

Robot Lawn Mower Perimeter Wire Installation

The first tip is to be prepared to move the wire around after it has been installed. For this reason, I recommend laying the wire on top of the grass, rather than digging it in.

Figure 1 : Poor Return Wire Installation

My first attempt at laying the perimeter wire wasn't exactly a triumph (see Figure 1).

Our lawn mower is the excellent Husqvarna 105 / Flymo 1200 / Gardena R40Li, and I followed the instructions to the letter.

What I forgot, however, is that something the size of a robot mower doesn't easily pass through a gap in a fence.

In addition, the design of the mower actually gives you a way out -- in the form of the return wire (the blue line in Figure 1). How it works is this: the mower leaves the charging point (on the right) and mows the lawn at random.

When it runs out of power, it will look for the return wire, and follow it back to the charging station.

The trouble is, when installed as above, the mower will (a) rarely make it into the top-left, and (b) once it's there, it will run out of power looking for the return wire, which it almost never finds.

There are a few solutions to this. The simplest is to to carry the mower to the top-left, and then remembering to get if back again once it runs out of juice.

However, the saving grace comes from the mower's design.

Figure 2 : Better Return Wire Installation

Reading through the instructions it transpires that there is a way to get the robot to follow the return wire at the start of a mowing session.

This led to the solution in Figure 2. The black line shows the new location of the return wire, designed to help the mower find its way home.

At the same time, once set up correctly, the mower will, occasionally, start from the end of the return wire.

One last note: since I had already installed the blue wire, I didn't want to uninstall it, so I added a box that enables me to switch between the two. I'm cautious like that.

To achieve this, I used some kit from the following section.

Lawn Mower Perimeter Wire Maintenance

Although tough, perimeter wires can be broken. Especially if, like me, you've scrimped a bit and bought some lesser grade wire to extend the length of that which has been provided.

Figure 3: These are not the connectors you are looking for...

Here's a first hint: buy the wire that is recommended by the manufacturer. It's just better.

But, it's not indestructible, and so it helps to have a few bits of kit that can help you when the worst happens and someone cuts through it with a spade, or a rodent chews through it.

Or, more likely, one of the little terminal blocks that you used to connect two bits together fails.

These are not good connectors. They are not waterproof, and, over time, will fail you. In my case, it took about 18 months to 2 years before the first one failed. I've now replaced all of them.

The replacement connectors are hugely expensive. Luckily, I've found a place where you can get a selection of waterproof wire connectors for use on the perimeter wire, all very inexpensive.

My absolute favourite, though, is the damp-proof wire splice connector available through Amazon, pictured here in Figure 4.

Figure 4 : Better Wire Connectors

Firstly, they're not 100% waterproof, but I've found that this doesn't really affect them too much. Certainly not as much as a simple terminal connector.

They're also reasonably priced, and because you have to crimp them, they do hold better than some of the other solutions.

Finally, they're a 2-way and not a 3-way connector, so are less bulky when you have to partially bury them. The 3M ones that came with the mower tend to stick up and risk being sliced on the lowest blade setting.

With the connectors sorted out, there's just one item left: what happens when the lights go red?

Perimeter Wire Emergency Kit

The most common thing that happens is that one of the plugs at the back of the charging station pops out, breaks, fails, or otherwise needs replacing.

Figure 5 : Spade Connectors

Sometimes, it's enough just to push it back in. However, on occasion, they actually need to be replaced. Luckily, they're just spade connectors, and easily found on Amazon, for very little money.

In Figure 5, there's an example. For connecting to the Husqvarna / Flymo / Gardena base station, you'll only need the bit that crimps to the wire (perimeter / guide wire) and the other end 'plugs into' the base station.

However, these connectors also form part of my Perimeter Wire Emergency Kit, and can be used with any of the popular makes.

It's worth mentioning that any robot lawn mower with a perimeter wire needs a way for you to locate a break in the wire.

Typically, this requires connecting a 'flying wire' to the base unit (charging station) and then connecting it at various points around the perimeter wire to see where the break occurs.

But this is very troublesome if you need to go around breaking the wire and connecting a 3-way block to the perimeter wire before plugging in the flying wire. 

Figure 6 : Self Stripping Connector

Much easier is to use the self stripping connector type, as shown in Figure 6.

All you need to do with these is place them around the perimeter wire (with flying wire connected) and gently press the cover closed just enough to make the connection, but not enough to seal the connector.

If you press too far, don't panic, just leave it where it is.

These connectors are so cheap that you can afford to leave them in place -- and if you mark where they are, the next time you need to investigate a break, you just need to march up with your spade connector on the end of the flying lead, and plug it in!

One last tip: the flying wire need not be the best quality, but is must be long enough to run to the most distant point on your perimeter cable, as measured from the charging station.

So, those are the current robot lawn mower perimeter wire tips and tricks, from a few years of robotic lawn mower ownership. Feel free to add your own solutions in the comments below!

Gardena Robotic Lawn Mower Review

We have owned the Gardena R40Li robotic lawn mower since I started this blog, back in 2013. In fact, one of the reasons I started the blog was to share my experiences and decision process, and as such now feels like the time is right to write a full Gardena robotic lawn mower review, having lived with the beast for three seasons.

For those who don't have time to read the full review, here are the bullet points. First, the good:

• The grass has never looked better;
• I got time back to do railway modelling instead;
• The whole experience has been almost pain-free.

Now, the not-so-good:

• Yes, it was expensive;
• Yes, parts fail (if you don't take care of it);
• Yes, moving the perimeter wire can be a pain.

The conclusion -- I would buy it again, but I'd take better care of it (i.e. clean it properly) and set it up a bit differently, probably getting in an expert to do that with me. After all, they did offer a free consultation!

Gardena Robotic Lawn Mower Installation

Installing the mower looked so easy on the DVD that came with it that I decided to go it alone, despite the kind offer to have someone come and help me install the perimeter wire (for free). One Sunday afternoon, instead of actually mowing with the old petrol-fired behemoth that it was to replace, I got stuck into the installation process.

The R40Li comes with it's own charging station, which sits on a perimeter wire, which stops the robot going off and mowing the tulips and neighbours drive when it should be doing the lawn. There's also a kind of follow-me cable that hooks up the mid-point of the perimeter wire to the charging station.

The idea is that, if the robot runs out of juice, it can find the wire, and subsequently find its way home. This is a system that works very well, but also has a dual use, as the wire can also be followed to a hard-to-reach part of the garden in case the mower is in danger of missing it due to a narrow entrance.

This is, in fact, something I regret not having done. 

Instead, my return loop is just a straight line. Having connected everything up and left it there for three years, I'm wary of upsetting the apple cart by relocating it, and probably the professional installer would have spotted my error straight away!

Other than that, once everything was in place, pinned down with the black plastic pegs and connected with waterproof 3M connectors (all supplied in the box), and plugged into my outside plug socket -- note, this is indispensible -- the mower charged up and was put to work.

It does take an afternoon of hammering little pegs in, testing electric circuits, and crossing fingers on occasion, but you can do it on your own. Just try to think it through a little bit more than I did!

Operation of the Gardena Robotic Lawn Mower

The mower runs on a daily programme, which can be varied through the slightly confusing on-board menu system. Be prepared to keep the instructions to hand for the first few weeks, as you'll be fine-tuning things like the time of day the mower should operate, and the number of times it follows the cable to the end before starting a run rather than just setting off in a random direction from the base.

And, the mower is governed by randomness.

It sets off when its charged, but pretty randomly, in a random direction, and changes that direction by a random amount whenever it hits an obstacle, or reaches the boundary perimeter wire.

Repairing the perimeter wire is also part of the ongoing operation and maintenance of these kinds of robotic mower, and it is a bit of hassle. Here's a tip: make sure you keep a long piece of single-core wire handy for troubleshooting, and don't bury the wire intentionally; just let the grass grow over it, or cover it with thin paving stones that are absolutely level with respect to the lawn.

The reason for this is that fault finding requires connecting one end of the cable to the base unit, and then hooking the other end to various points on the perimeter until you get a green light.

After the first few times, it gets a lot easier; but for that first time -- make sure you have wire handy, as well as a knife to scrape a little plastic off the perimeter wire, a crocodile clip to connect the wire to the perimeter cable, and some electrical tape to fix it up after...

Parts that Failed on the Lawn Mower

The first item in this category -- blades -- isn't really failure. You need to change the blades every so often.

Tell tail signs that the blades need replacing are:

• Wobbling mower caused by uneven weight distribution (one might be broken);
• Unusual noise;
• Grass tips going brown (unevenly cut; more torn than cleanly cropped).

Luckily, removing them is child's play; but don't let a child near them because they're sharp! They just unscrew from the underside, and the packs of replacement blades come with new screws and full instructions.

Then, the wheels came off. Actually, that's not true. What happened was the rubber came off, and the wheels stopped gripping (this was after 3 seasons use, with no over-wintering). The replacements have a solid, moulded tread, so they'll last for the rest of the product's lifetime.

Also this year, the dampers broke. The rubber perished, and they stopped preventing the outer bumper from bashing against the collision detection system, as discussed here.

Other than these few points, which encourage me to take much better care of the mower (i.e. cleaning it and overwintering it properly), the last three seasons have been trouble-free.

Summary - Should You Buy a Gardena R40Li Robotic Lawn Mower?

Here's the thing -- I can't answer that, because I have no idea whether your lawn qualifies. However, if you hate following your mechanical mower around a pretty standard lawn, then I'd certainly consider it.

The Gardena R40Li Bumps Up Against A Problem...

So, having swapped out the rubber-tread wheels for nice, new shiny plastic ones (see: And Then, The Wheels Came Off!) the next bits that have failed are the two rear rubber dampers. These are going to need replacing, but first, let's take a moment to look at the symptoms and probable cause.

Before we do that, I'd encourage anyone that has the Gardena r40Li, Flymo 1200R or Husqvarna 305 to download the following exploded parts diagram from the Gardena web site:

• http://www.gardena.com/ddoc/GARI/GARI2012_AAaa/GARI2012_AAaa__R40Li.pdf

And, whilst you're perusing it, and probably going "Ah, that's what that bit is!" at the same time, remember that we've had the r40Li since 2013, and this is only the second repair that we've had to do. Yes, I've changed the blades a couple of times per season -- thanks to the kids, the grass is littered with twigs -- but this is only the second major bit of work I've had to do.

This is despite the fact that I'm not the best at cleaning, or winterising the robot mower, which is where I suspect the cause of the current problems lie.

The Odd Symptoms of Bumper Failure

On the face of it, I should have realised straight away that something was amiss.

The mower would stop, mid-mow, for no reason, and then reverse. Then, it would turn and head off  in a direction, before stopping again, reversing, turning and trying to get going in a number of different directions before giving up.

Having turned itself off, a restart listed a "collision detection failure" a few times, before I twigged that maybe this wasn't simply a question of the mower getting stuck in a corner.

So, I picked it up.

When I did so, grasping the cover, including bumpers -- look at the diagram, p.13 -- and the chassis listed alarmingly. Normally it bobs around, suspended, as I now know, on four rubber dampers, that give it flexibility and allow for the bumper to detect collisions.

Now, with one broken, it registers a permanent list to one side, and the inevitable bumper failure with it.

What Caused the Rubber to Perish?

Both the rear dampers have perished. Possible causes that spring to mind are:

• snails (and I'm not kidding: they eat the post!);
• cold (changes in temperature attacks rubber like nothing else);
• bumping into objects.

That last one is pertinent, as although the perimeter wire went in three years ago, we're still moving it around to get the best edge cutting possible. Thus, the mower spends a lot of time bumping into stone edges because the perimeter wire is just a little too close to the coping stones...

On the other hand, the amount of dead grass that I pulled out also hints that maybe that also had something to do with it.

Either way, my advice would be to:

• clean,
• winterise,
• avoid snails,
• place the perimeter wire a good distance away from any coping stones...

For readers with the same issue, the parts are numbers 574 46 91-02, and they cost around 7.50 EUR each plus delivery. Much less than the wheels; and I'll let you know how I get on swapping them out with the damaged ones.

The verdict? Still recommended!

Is This Just The Most Expensive Anti-Mole & Auto-Mulching Device Ever?

It's been a while (3 years) since I received the best time-saving gift ever, in my opinion.

Had I listened to the naysayers, my friends and colleagues included, I would have been gearing myself up for a life spent hunting for perimeter wire breaks, changing spinning blades, unclogging the mechanism, replacing batteries, fixing electrical shorts, etc. etc.

In fact, the Husqvarna (sold also under the Gardena and Flymo brands) robotic lawnmower that I have has required less corrective maintenance than the old walk behind Briggs & Stratton powered mower that I still haven't had the heart to throw away.

That mower had issues ranging from a continuous problem with the traction drive belt (it's a heavy thing, and having it pull itself was a very desirable feature!) to a blade that was nearly impossible to take off, sharpen, and once put back never spun evenly, threatening to tear the engine off the plastic chassis!

Next to these issues, replacing the wheels when one began to fall apart, and regular blade replacement fade into the background, and both tasks are extraordinarily easy to complete. No expensive over-wintering costs, either, or replacing the engine oil, or any other of the messy jobs that you usually associate with lawn mower ownership.

However; there are a few things that I've noticed in the last three years, and are worth pointing out.

No More Moles!

The first thing that comes to mind goes back to a comment to a comment that I made back in 2014: to do with rodents eating the wire. At the time, one of my readers had pointed out that his Honda robotic lawnmower was suffering because foxes were eating through the guide wire.

My answer was to bury it deeper, thereby protecting it from ground level interference, but not from moles, which I also assumed would find the wire from time to time.

How wrong can you be?

It turns out (and this is just anecdotal - if anyone can back it up I'd be interested to hear their stories) that the number of moles in the lawn area, as evidenced by the (lack of) molehills has dropped to pretty much zero.

We used to have an issue with moles, and in the past I'd even installed one of those mole stop devices which send a subterranean pulse to warn the little blighters off, but it broke and never got replaced. 

Needless to say, the moles came back.

With the robotic lawnmower installed, however, they seem to have gone away again. I know they're in the area, because the field has been attacked, as have the neighbours' lawns (albeit to a lesser extent than before), but within our perimeter wire -- nothing.

There's a couple of explanations I can think of:

• the irregular noise of the mower mowing creates vibrations (like the mole stop devices) that scare them away, or;
• the electric fields made by the perimeter wire and guide wire are keeping the moles at bay.

Either way, the lawn looks better for not having any mole hills, and being greener thanks to the continuous mulching that tales place thanks to the mower's regular operation and small cutting length.

The Grass is Greener on All Sides

Just a small note here, but we have noticed an improvement (and being smart after the fact I wish I'd taken photos!) in the quality of the lawns. They are greener and more lush, presumably down to the mulching.

My walk-behind mower actually had a mulching blade fitted because I'm pretty lazy and didn't want to have to (a) empty the grass box somewhere, and (b) dispose of the grass. So, I just let the blade spin, reduce the grass clippings to dust, and let them fall where they were.

However, for this to be effective you need to mow the lawn every few days in the summer; especially because, a bit like hair, if you cut it regularly and take care of it, a lawn tends to grow faster!

Did I mention that I was lazy?

I'll admit it: to the cynic, this sounds like an expensive anti-mole and auto-mulching device, but the net effect is a healthier lawn that looks great.

My next project is to fit a couple of cameras so you can see it in action: you might even get to see it scare off a cat!

The Robotic Lawn Mower Perimeter Wire Revisited...

Fitting a perimeter wire often requires breaking and re-connecting individual cables together; and when you buy a robotic lawn mower, they come with a selection of appropriate connectors. These, however, are quickly used up, and especially if the wire breaks (which it will do), leading to a hunt for replacement connectors.

Perimeter Wire & Guide Wire Breakage

For robot mowers that use perimeter wires, there are usually two ways that the wires are used:

• as a boundary for the work area;
• to guide the mower to the charging unit.

While any wire break is irritating, breaks in the boundary wire present more of a headache than the guide wire, as it involves investigating the whole loop. The instructions for the Gardena 40Li / Flymo 1200R show that there are three connection points on the base: two for the boundary wire and one for the guide wire.

There's also a light on the base (where the mower 'docks' -- you need to take it out to see the light) which has several states. States related to the boundary and guide wires are:

• Green -- all okay;
• Blue flashing -- break in the boundary wire;
• Yellow flashing -- break in the guide wire.

Fixing the guide wire is easy enough, as you can trace it fairly easily (I made a plan of my own installation!), and splice the wires together.

Splice Clips

To do this, I use a splice clip, pictured here on the right, which costs about 2.5 EUR for 20 (less than 4 GBP) delivered, from online retailer Banggood.

These might not be water protected like the 3M ones that came with my Gardena 40Li, but they do the job adequately, and are a lot better than the 'sugar cube' type blocks that I was using previously, which tended to rust.

These clips can also be used to repair the boundary wire, once you know where the break is!

The instructions for doing this can be a bit confusing, but the diagrams in the user guide are pretty self-explanatory. However, since they require plugging a flying wire into the base unit, and then using it to test ever-increasing sections of the perimeter wire, I found using a terminal and spade connector made things easier.

I found these on Banggood at the same time as the splice clips (click here), for less than £2 per pack of 5. One of the 'spades'can be attached to the end of the flying wire, of which the other end is plugged into the base, in place of the regular other end of the boundary wire.

Terminal/Spade Crimp Clips

The t-connection bits end up on the boundary wire -- there being no way to take them off -- but are useful each time there's an issue.

As long as you remember (or write down) where they are, you can troubleshoot that much more easily, as well as 'shorting' between two points if you want to limit your robotic mower for some reason.

To do that, all you need is a bit of wire, the right length, with a spade at each end, and two points on the perimeter wire with a t-connector between which to put the flying wire. Now, when the mower approaches it, it will treat the new wire as if it is the boundary wire.

Simple!

...And Then the Wheels Came Off!

It sounds like the punchline to a bad joke, but what do you do when the wheels come off your Gardena robotic lawnmower? The answer is simple, if a little long-winded: go back to the retailer and ask them to order new ones...

The Problem

The Gardena 40Li, Flymo 1200R, and Husqvarna 305 all look remarkably similar. In fact, I'd put money on the fact that they're all made by the same company, to the same design, which I'm fairly confident is Husqvarna itself.

To my knowledge, all of these share the same kind of wheels: a plastic hub and a rubber tread.

And here's the problem. After nearly 2 years of unbroken service (aside from over-wintering), my Gardena 40Li's wheels have come off.

Actually, it's just the rubber tread that has become worn out, and I found it lying on the damp lawn, with the poor mower comically pirouetting with one tread-less wheel being dragged around by the other, rubberised one.

The solution ought to have been simple -- in this day and age, surely it's possible to order Husqvarna parts online? Unfortunately, it proved to be a bit more tricky than I'd thought.

Out With the Old Wheels

Without the rubber tyres, not only can the mower not mow efficiently, but it also can't dock itself for charging, since the designers decided that the best way to achieve this would be to reverse the mowers onto the outdoor charging stand.

This means that they have to spin around (always turning the same way) and by coincidence, it looks rather as if it's the outside wheel that has come off worse and eventually failed.

So, repair is out of the question. De-rubbering the wheels is out of the question. Perhaps there's a DIY solution (let me know in the comments thread!) but the most obvious option is to replace the rubber treads.

In With the New Wheels

However, it seems that someone on the design team has realised their error with the wheels, and rubber treads aren't available, but nice, shiny, moulded plastic (with treads) wheels are.

They cost me around 25 EUR from the dealer, for a pair, and took a while to arrive -- they were permanently out of stock at the central stockists -- but when they did, they proved easy to remove and replace.

If you look at yours, you'll see that there are three torque type screws to remove, per wheel, which can be a bit tricky, due to the angles, but it can be achieved without dismantling the mower itself. This may not be the case for the original Husqvarna 305, but the Flymo 1200R and Gardena 40Li succumb to the direct approach easily!

The new wheels came without screws or washers, so you'll want to keep those and not throw them away when you dismantle the old wheels.

Besides the blades, and the occasional accident with the perimeter wire, this is the first 'major' part of the mower I've had to replace in 2 years, which makes it an immediate improvement over the old Wolf Garden manual motor-mower I used before, which suffered wheel-failure (traction belt) in the first year, and needed to be annually maintained by the local dealer to keep it working properly!

The next thing I expect to go will be the battery; I'm not sure what the lifespan of these is supposed to be, but we've already noticed extending charge cycles, and diminishing mowing times. Of course, without an actual measurement/download facility, that's anecdotal, but to be expected.

Still, being able to change the wheels myself, and as easily as changing the blades (despite having to shop-order them) removes another of my initial concerns about owning a robotic mower.