Lawnmower Blade - Bigger is better?

[dishman]

I have a flymo hover compact 330, about 7 years old. It has a 330mm blade hence the 330 in the model number. The motor is 1450watts.

The blade was/is past it's best and I have sharpened it so much it is now very much out of balance.

I came across an old (not working) similar model with a newer blade intact and in good condition. Rather than let it go to the skip I decided to cannibalize it for parts.

I realised that the model I had cannibalized was the one above mine, an 350 with, you guessed it....a 350mm blade.....

The only other difference is that the motor is 1500w, so only 50w more powerful than mine. The chassis and everything else is exactly the same....

Question:

Is the difference in motor and the longer blade purely just marketing nonsense?

I cannot see how an extra 50w is required for the 35cm blade. I assume it must be that is just the "model above" marketing difference.

 

[Deleted2797112]

The wider the blade, the shorter the time to cut the lawn as fewer passes are required. I'm no expert on engine sizes but I'd guess that a longer blade is heavier and needs a bit more grunt to achieve the same speed.

 

[big-all]

not sure why you dismiss it lightly as a gimmick

the blade is 6% bigger so needs greater power to perform at the same level and speed
the motor is only 4% bigger so will be slightly underpowered

 

[dishman]

You say that, but (as a separate consideration) Flymo have just re-designed the correct sized replacement blade. They seem to be far more substantial in their re-design (heavier) than the original.

If the motor was designed to be so marginal on power when factoring the blade, why re-design a more hefty blade....

But, I was considering your point, just wanted to see if other people thought a 6% bigger blade would require a 3.5% bigger motor?

 

[big-all]

there are loads more factors to consider really
extra mass is not nesiserrily a problem if the energy absorbed by the grass is less than the energy stored in the mass it will not slow down to any extent

a greater mass is often used to average out the load on a cycle with storing enery to cope with high spikes

 

[Burnerman]

The motor may take longer to get up to speed, but.......
As its a hover machine, the blade needs to fill the plastic skirt to get air control. Just check that the new blade will physically go in.
John

 

[dishman]

Yes, the chassis is the same size for both, that is what got me thinking. In fact, flymo still use the same chassis and model structure today. The design has just been jazzed up.

The more I think about it, the more I guess it has to do with grass resistance.

The motor (even if the standard blade is used) has to be powerful enough to spin the blade with high resistance from the grass (if it is thick and long).

So the motor has to have the extra capacity to cope with that scenario.

A slightly larger blade will in itself not seem to trouble the current motor. However, with a larger blade comes a larger cutting area, which may indeed put more strain on the motor if the grass is especially thick.

The question is, would the extra 50w really make that much difference.

 

[Diyisfun]

Is the wattage a calculation OR a motor that is available. That is the question

 

[dishman]

What do you mean?

One says 1500w on the back the other says 1450w

 

[Diyisfun]

What do you mean?

One says 1500w on the back the other says 1450w

What I mean is ' What made Flymo select a motor with a particular wattage'
Availability or design?

 

[dishman]

It is consistant along their range.

So the better model you get, the slightly larger blade, and a slightly more powerful motor. Usually in incriments of 50w.

 

[Deleted2797112]

So the better model you get, the slightly larger blade, and a slightly more powerful motor. Usually in incriments of 50w.

Slightly larger blade and slightly more powerful motor aren't necessarily 'better'. It depends on what you're cutting and the user. I have two Flymos - one small and one large and, for me, the small is 'better'.

 

[dishman]

Well, out of interest, I opened up my existing flymo lawnmower (the one with the 1450w rated motor) and compared it to the motor I removed from the cannibalized one rated at 1500w.

They look identical. I could not see any difference, not even in size nor weight. So very interesting as to how flymo rate these motors.

Anyway, regardless, I put the larger 350mm blade into my model lawnmower and it works fantastically. No problems at all.

As I said, the model I got it from was pretty much in a skip. Whoever threw it away, all they needed to check was the drive belt which had snapped!

Now I have a new blade and spare parts for my mower (including a motor) for free!

I even re-used the micro switch in the handle as mine had started to get a bit faulty.

I love it when you can re-use/repair somthing and save it from needless binning.

 

[Mursal]

I wouldn't stress to much about 50W, because the voltage coming in from the mains can be + or - 10% of the rated voltage of 240Volts. So this will have more affect ......

Great to have all the parts, we do the same with the washing machines. Its only when it breaks again (probably never) you will see the benefits ....

 

[D4N1EL]

Just an idea but if it's a hover mower, will the motor turn the bigger blade fast enough to lift it?