New lawnmower blade boss broken TWICE

[pvcpro]

Hello.

I bought a new lawnmower and on the first cut the blade boss broke, the two little lugs that go through two holes in the blade literally sheared off, I only used it for about 2 minutes before I heard a dodgy rattling noise and then it got louder and went berserk so I stopped the engine, looked under the deck and sure enough the blade was loose and the two lugs were gone.
Contacted the seller who said straight away I must have gone over a large rock or tree root and as a good will gesture would send me a new part for me to fit, I wasn't happy so kicked up a fuss and eventually they agreed to a replacement mower.

I used the new replacement mower for the first time yesterday and this time managed to nearly all of the lawn cut until right at the end I heard a dodgy noise again, the exact same thing has happened and both lugs have sheared off.

The seller is proposing I send the mower back for them to investigate and repair but I'm now a bit sceptical about it and fear it will just happen again, surely the boss material is not strong enough, not sure what material it is but it looks like a soft metal.

Should I accept a repair or just chase them for a refund and look for a different mower?

Thanks

 

[foxhole]

Make and model?

 

[pvcpro]

Mountfield HW531 PD Self-Propelled 4-in-1 Petrol Lawn Mower

 

[Alec_t]

Get a refund .... and a different mower!

 

[HERTS P&D]

Did you have to put it together? and how long was the grass you were cutting?

Andy

 

[pidgeon1]

Did you have to put it together? and how long was the grass you were cutting?

Andy

Just looked this mower up It costs a pretty penny see description on web

This rugged mower is more than capable of tackling large, uneven lawns.​

 

[magicmushroom666]

I'm wondering if the blade is supplied loose and you have to fit it properly or something before the first use? anything like that in the manual it comes with? Maybe a photo of the damage would help the mystery...

 

[Burnerman]

This is a pretty common occurrence, happily the boss isn’t expensive or difficult to replace.
One of the main reasons for failure is to crunch on concrete or other hard earth - the lugs shear off but it does save a bent crankshaft!
Make sure the centre 14mm bolt is tight at all times, and you can replace the lugs with 8mm bolts if you like but obviously there is some risk.
John

 

[pvcpro]

The only thing I had to do was connect the handle, the grass wasn't long and I didn't choose a low setting either so was only trimming the lawn. The blade is spotless not a mark on it, I even took pics of the blade and emailed them to the seller.

 

[Burnerman]

I replace three or four of these bosses per year...they are aluminium alloy with a fairly high zinc content so they aren't that tough - but they don't smash on their own accord!
I'd suggest the central bolt (conventional RH thread, 14mm) just wasn't tightened enough. There is usually a dished spring washer on the bolt too, that flattens when the bolt is fully tight.
There are many of these things on ebay or whatever, and they are rarely machine specific - if you want to go your own way with the repair.
John

 

[pvcpro]

I'd have thought if the central bolt wasn't tightened enough then the issue would have happened pretty much straight away but I nearly finished cutting my whole lawn so was using it it for about an hour before it happened.
I definitely did not hit anything, the area I was cutting is completely flat and even.

 

[Burnerman]

I can’t add much more to this one, but on bosses that I have seen damaged, the blade has spun a little and tightened itself up against its bolt - so I wind mine up tight.
Where do you intend to go from here?
Regards
John

 

[pvcpro]

The seller wants to collect it for inspection and possible repair, which is fine apart from the fact that I know it's going to keep happening and they won't continuously do that will they, I said that I would like a refund as I'll need to look for a different mower but they said I would probably end up with another mower with a similar blade boss as that's how they are made now, obviously manufacturers milking the consumables after sales market.
Someone mentioned fitting steel bolts instead of the weak lugs but I'm not sure I'm up for adapting brand new machines just so they actually work!

Not sure what to do now.

 

[lostinthelight]

There are mowers that don't even have lugs so as John says you probably haven't given them enough welly.
Just make sure you have the washer the correct way up which is the outer edge touching the blade and dome side in contact with the retaining bolt head.

 

[Burnerman]

If I need a boss repaired sharpish, I drill the holes 6.5mm and then tap out to 8mm and wind in two allen screws......this works well enough and there's enough material to do this.
Some mowers - the Honda range for example - have a steel boss and two bolts where the lugs are.
John