Can Mountfield cutting height be lowered to 20mm?

I can't be sure but with an electric lawnmower I believe you are stuck with the heights the manufacturer decides.
If it was a gas powered mower there are a couple of things that might work. The easiest of which is buying a different "hub" to which the cutting blade is attached. However, I think with electrics your choice of replacement "hubs" is either non existent or very limited.

Jilli, thanks for your response. I should have clarified, my Mountfield is gas (petrol in the UK) powered. Reference the hub, I assume I need to be contacting a lawn mower specialist? Is it easy to fit myself?

Hi Tony,

The hub is fairly easy to replace. Under the mower deck you will see the blade which is attached to the end of your crankshaft with a bolt and two washers. One washer is a lock washer and the other is probably slightly cupped. Under the blade there is a metal attachment that fits over the end of the crankshaft .... this is the hub or blade attachment. It holds the blade and acts as a spacer for the blade from the end of the shaft. Your crankshaft diameter will probably be about 7/8" and will have a keyway for some kind of key to stop the hub and blade from spinning on the shaft. From the parts breakdown diagrams for most of the Mountfields the key is a Woodruff key or "halfmoon" shape. To remove the blade, first disconect your spark plug. You will need to block the blade against the inside of the deck to stop it from spinning. The head of the bolt is probably a 9/16" (unless the motor is a Honda or other Japanese make which are metric sized) and you will need that size socket. The bolt will be very tight. Once the bolt is removed the blade should just "fall" off. The hub should just slide off the end of the shaft. Sometimes the hub sticks due to build up of grass debris or rust on the shaft.

Over here there are "generic" hubs available that can be slightly longer than your Mountfield hub. I'm not familiar with the Mountfield brand....as far as I know they are not sold under that name over here. Try going to a lawn mower repair shop and take the hub with you along with the model number and serial number of your mower. A good repair shop will have a variety of hubs available and will be able to supply you with one just a little bit longer than your original. This may mean that you will have to buy a new blade that will fit the new hub. All hubs have different methods of connecting to the blade and what fits one won't fit another.

When you reattach the blade make sure that the bolt is tight. The blade goes on with the bevel on the blade facing the mower deck. You can try that or take your whole mower to the repair shop and get them to attach the blade for you with either an compressed air tool or at least a torque wrench.

That's the best I can do for you from over here. I know what is available here and have done this on many mowers but that doesn't mean that the same will be available over there. Good luck

Gilli

Gilli,
Blimey you sound as though you know your stuff.

I think I'll first of see how much a repair shop will charge. If reasonable let them do it. Especially as I don't have a torque wrench, plus I always get the most difficult bolts to remove.

It as got to be worth it other wise I'll have to consider selling the mower, hoping to get half of what I paid (being only a year old), and then forking out for another.

Many thanks for your time and assistance, really appriciated.

Tony (from Sunny Sheffield)

You're very welcome Tony. Glad to hear it's sunny in Sheffield. I'm from Wakefield originally......many moons ago.