Mower Pro blades came loose, anyone else seen this?

Support & Solutions
,
1

Soooo…. Has anyone else had a problem with the straight blades coming loose on the Mower Pro?

I ask because yesterday I got a mower blocked message in a spot that previously hadn’t had an issue. I checked the mower when I got home and didn’t see any issue and sent the rover back out. Then it got blocked again. This time it ran over the cover for my septic tank. I got it off, and then had it restart in a different location and it was making some fairly loud (compared to normal) noise that definitely sounded like something out of balance. I stopped the mower again and check the right motor and notice that one of the two screws for the blade was missing…. I thought it broke off.

I got the mower in the garage, got the module off and turned on it side, and found that BOTH blades were loose. The right hand motor only had one screw in it and it was about out, and the other blade had both screws loose….

Now, those look to be a #12 or like a 3-4mm screw. I made sure to snug it down pretty good, but I don’t know what material the hub for the blade was made of and didn’t want to risk stripping out the threads or breaking a screw, so I didn’t go cranking on them. But I also noticed that several of the screws in the kit had thread locker on them… Now I’m wondering if the screws for the straight blades should have had thread locker on them? Or was I supposed to add it?

20251113_221612
20251113_2216121920×3950 989 KB
20251113_221616
20251113_2216161920×3950 1.27 MB

Because, now I don’t know whether the screws came loose first and caused the blades to hit things they should have missed, or whether the blades hit things and that somehow caused the blades to come loose in a matter of seconds… And I’m not inclined to believe the latter.

And now my blades look like this:

20251113_221313
20251113_2213131920×933 323 KB

20251113_221319
20251113_2213191920×933 331 KB

And while were at it… Can someone explain why there are Allen head screws here when the manual EXPLICITLY says they should be Phillips head and even shows using the supplied screw driver for those screws? At the end of the day I’d rather have the Allen head screws, but I’d really like the description and supplied tools to match the hardware. I mean, did you print up the manual a year in advance? Even if you did, would it REALLY have been THAT much of an imposition to print up a couple of extra loose pages with updated instructions and send them as errata or appendixes? I can’t tell you how many products that I’ve received with corrections just like that, from computer software, to power tools. Heck, I’ve even seen where they take the updated page and actually glue it in the manual over the old page. At the end of the day I DON’T CARE ABOUT A PRETTY MANUAL, I WANT A CORRECT MANUAL!!!

And you know what looks worse than a manual with patches and extra pages glued in? One that is completely inaccurate or incomplete!

20251113_221600
20251113_2216001920×933 312 KB

With all that said, @Yarbo-Forum I need some direction here.

  1. Should I apply a thread locker to the screws?
    1. What brand/part number should I use?
    2. If the screws should have thread lockers, will you be pre-applying thread locker to the screws you supply in the future?
    3. If I should, why was this not mentioned in the manual?
  2. Please supply torque specs FOR ALL SCREWS AND BOLTS that we should be interfacing with!!! This includes the RTK antennas, the screws for the antenna mounts, the side plates on the treads, AND ESPECIALLY THE SCREWS FOR THE MOWER BLADES!!!
    1. Basically if it is anything to do with the functionality and or operation of the unit, and we’ll be expected to screw/unscrew it to setup, repair, or operate the unit, WE NEED A TORQUE SPEC!
    2. If you DON’T already have specs for this, then you need to figure them out. Much like my issue with the antenna mount, this is something that should have already been figured out. And not having these kind of specs would be extremely worrying regarding the reliability and SAFETY of this product.

I want to make this INCREDIBLY CLEAR. THIS IS A SAFETY HAZARD! Imagine if that blade had come completely loose and hit a car, or worse a person!

PLEASE FIX THIS!

2 Likes
2

Open a ticket if you haven’t already. I’d say it wouldn’t hurt to apply blue loctite.

2 Likes
3

My only concern with that is (assuming the screws are steel) blue loctite in particular can get VERY aggressive when used with certain metal combinations because when it fractures, it becomes almost glass like and can cause threads to gall then become impossible to non-destructively disassemble.

Don’t ask me how I know about that one. :roll_eyes:

At the end of the day I’d prefer to hear @Yarbo-Forum ‘s recommendation. If it’s Loctite specifically, should I use 243 or the specifically removable 242 grade? Would it better to use 222? Should I instead use 263, but just a small drop? Or would some other brand be better?

3 Likes
4

done.

Ticket #130868

2 Likes
5

That will hopefully get you some answers quicker. It’s the weekend now for them.

1 Like
6

I had the same thing happen with the Pro model too! But even worse! :wink: On the deck, some screws broke even though there’s no rock where it was mowing, so I lost three, and one took the blade, bolt, and screw with it! They came completely loose, not just unscrewed. Now, where I did better is that I managed to break one of the large Pro blades in two, but I haven’t filed a ticket for that yet! For the deck with the six small blades, I documented it and filed a ticket :wink: !!!

2 Likes
7

Ok…… Now I’m really concerned….

Partial response to my ticket:

image
image768×154 9.36 KB

Funny, I KNEW the specs weren’t in the manual….

THAT’S WHY I WAS $#@T@#$&@$ ASKING FOR THEM!!!

BECAUSE I DON’T WANT THE @%#@&@# BLADES TO COME OFF WHEN IT’S RUNNING!!!

3 Likes
8

Yes….we read the manual… < shakes head / >

2 Likes
9

Lol

1 Like
10

Hi there, thank you for taking the time to document everything so clearly — we truly appreciate it, and I’m very sorry for the frustration this has caused.

To address your questions point by point:

  1. The straight-blade fixing screws do come with thread locker applied from the factory.
    If the screws have been removed or replaced, we do recommend reapplying thread locker during re-installation.

  2. Recommended thread locker brand:
    • Loctite 243

  3. For future batches, we will be switching to screws with pre-applied thread locker to prevent this issue from happening again.

  4. You are right that the manual could have been clearer on this point.
    We apologize for the missing torque specs and the inconsistency between the documentation and the actual screws used. I‘ve reflected this to our product team.

  5. Torque specification:
    The tightening torque for the screws is 45 kgf·cm.

We take safety concerns very seriously, and your feedback is extremely valuable for improving the product. If you need any other assistance, please let us know — we’re here to help.

6 Likes
11

39 lb-in or 4.4 nm to save you a Google.

6 Likes
12

Thanks @Tom.C

2 Likes
13

20251113_221612
20251113_2216121920×3950 989 KB
20251113_221616
20251113_2216161920×3950 1.27 MB

@Yarbo-Forum just to make it clear, as the left picture shows, NONE the bolts I received for the straight cutting blades had any kind of thread locker on them that was visible. There are a couple of the bolts for attaching the small blades to the cutting disks that have thread locker on them, but the ones for the large straight blades do not.

I also, when this event happened, it was night time and I did not have the opportunity to really go out and look for any other parts as I realized a little later that I was missing the protective blade caps. I spent some time over this weekend and managed to find the caps. I would appear that when the rover ran over the cover for my septic tank the blade protectors must have hit the lid causing the screws to pull through the cap. Since the screws were holding both the caps and the blade, when the caps came off it left a gap and the screws were no longer tightened causing them and the blades to be loose. At least that’s what I’m guessing happened. Looking at the protective caps, I would say that the design here is very poor unless they are specifically designed to fail (ablatively) in this way. The very small lip of the cap that goes under the screw head could easily be crushed under the force of tightening the screw and given the speed at which the blades spin with the torque I would imagine those motors produce I’m not sure there’s much chance of those covers surviving any meaningful impact. please see the pictures below.

20251115_160941
20251115_1609411920×933 348 KB

20251115_160934
20251115_1609341920×933 347 KB

It would probably be a good idea to design a metal version of that cap that uses all four of the available mounting holds in the hub to tie it down, rather than just two. Let the cap clamp the blade and hold it straight, and the four bolts hold the cap and keep it straight. Letting the blade contact the screws directly is not the best design. And it’s obvious that someone had this thought as the straight blades have a small indent in their sides to not block the other two mounting holes in the hub. :wink:

3 Likes
14

Oh, and thank you @Yarbo-Forum for providing the above information. That will be very helpful.

4 Likes
15

And to save the conversion… :wink:

4 Likes
16

Yeah, that’s where I was going with that. I’ve never seen kgf·cm before this post so I googled what that equates to in other units. Hopefully it didn’t come off as snarky.

3 Likes
17

Not at all. I had no idea either.

2 Likes
18

Me either. I’m just glad @Tom.C read it before me. Saved me from googling it.

1 Like
19

Hi there, thank you for sharing your detailed feedback and suggestion. We really appreciate the time you took to explain what happened. Regarding the design of the straight blade cover, I’ll pass this along to our mechanical R&D team for further evaluation. If you have any additional observations or suggestions, feel free to let us know — your input is very valuable to us.

2 Likes
20

Well I received the new blade caps today…. They are… interesting……

New on the right, old on the left…. Top Views

image
image847×454 81.8 KB

image
image931×392 63.4 KB

Bottom Views

image
image959×545 125 KB

image
image992×469 102 KB

Interesting that there are now pins that fit into the unused screw holes and also now wraps around the sides of the hubs. Also interesting that there is now a reverse chamfer where the blades would extend out from under the cap… Seems like a perfect place to collect debris that could act like a wedge with the chamfer to force the cap off. Hopefully that won’t be the case. Nice that the shoulder under the screw looks to be a little thicker. And I’m not sure if the cap is thicker over all, but it does feel a little heaver than the old cap.

It may be too late this year to try them out, but I’ll be looking forward to putting them through the paces next spring.

4 Likes