Lawn mower blade sharpening

[The Hawk]

I remove the blade and use a bench grinder to sharpen both sides. Don't forget to balance the blade after sharpening.

 

[DRW]

...He said that he doesn't remove his deck.
...

Mower lifts leave the deck atatched.

 

[kreisl]

i sharpen them manually with a 100mm short ceramic cylindrical rod (10mm diameter, rubyred color), value 1$ shipped from Alix.
gonna sharpen one today. i do so once every year or every other year.

years ago i had used 1inch-wide diamond rods from a guided-sharpening system (~Lansky) but imho the cylindrical rods are more versatile in reaching and sharpening every millimeter of the edge.

 

[bykfixer]

A friend of mine is a lawn care guy who says to use a 3/3/3 method for the home owner who cuts their own grass. Cut it 3" tall, sharpen the blade every 3rd cut and replace it every 3rd year.

Mine is 12 years old. I use a 3/3 method. Cut grass 3" tall, sharpen blade every three years.

 

[knucklegary]

@kreisl, Do you remove blade and mount on bench vice to sharpen?
If not, make sure you disconnect spark plug boot before rotating blade while mounted to motor.

 

[kreisl]

@knucklegary Yes i remove the blade, interestingly the pivot screw isn't tighted much at all. No vise for this hehe. Just finished the task, in front of the PC screen, blade in my lap, while watching ROME1000 semis. I had posted a pic from a past sharpening on wdyst:

http://bit.ly/wdystoday ("why dis today?" 🤪)

 

[Got Lumens?]

I always remove the blade(s) from the mowing deck.
No matter what you use to sharpen the blade,
care must be taken to take off the same amount of material from each cutting edge to maintain blade balance.
Care also needs to be taken to not overheat the blades edges while grinding to maintain the harness of the steel.
An unbalanced blade can wear out the Bearings of the blade carrier(hub assembly) very quickly.
This can cause unwanted repair expenses to replace the hub assembly >$50 to over $150 depending upon model.
If You do not use a magnetic bench blade balancer, using a common nail can do the job to make
sure the blade has been sharpened evenly from each end of the blade.
I use a combination of a 36 grit flap wheel and solid grinding wheel of hand held disc grinder to sharpen and deburr.
Slow and patient sharpening is my recommendation to achieve the best results.
If not confident, take the blade(s) to a mower repair shop for best results.
They can also let You know it's time to purchase a replacement blade(s).
GL

 

[Poppy]

Is the thread that holds the blade in place a Right Hand thread, or a Left hand thread?

 

[knucklegary]

Is the thread that holds the blade in place a Right Hand thread, or a Left hand thread?

Mine is right hand, tighten clockwise direction.. loosen counterclockwise. Torque specs who knows, I give it a good snug up with 1/2 drive ratchet

 

[Got Lumens?]

Is the thread that holds the blade in place a Right Hand thread, or a Left hand thread?

Every mower is different, but it has been my experience to observe righty tighty, lefty loosely.

 

[turbodog]

Is the thread that holds the blade in place a Right Hand thread, or a Left hand thread?

Every single one I've seen, along w/ farm equipment, is always right hand.

Only left hand threads I know of are: bike pedals, bike bottom bracket bearings, blade nut on some fans, and screws that hold drill chucks on.

 

[knucklegary]

Some motorcycles, countershaft sprocket/pulley nuts are left hand thread

 

[Bambuino]

half inch drill and some valve grinding paste sharpens my rotary pusher. use a hammer for peening out the scythe. liking the quiet life these days.

 

[High_Noon]

I don't advise using a grinder unless your blade is badly chipped. Unless you're very careful, a grinder will heat up the edge of the blade to the point where the temper is lost. At that point, the steel on the edge of the blade will be much softer and it will not remain sharp for long.

Get yourself a good mill bast-ard file and learn to use it correctly.

 

[Poppy]

Trying to think this through, I know that in Ford's, the idler pully is usually a left handed thread. One can look at the direction that the pully rotates when the engine is running. If the fan belt turns it counter clockwise, that would be the direction that would tighten the bolt (if it is a left hand thread), and vice versa.

I believe the picture below is accurate. And if so, then in order to loosen the retaining bolt, one would need to keep the blade from rotating in the cutting direction, while trying to loosen the bolt.

 

[turbodog]

I don't advise using a grinder unless your blade is badly chipped. Unless you're very careful, a grinder will heat up the edge of the blade to the point where the temper is lost. At that point, the steel on the edge of the blade will be much softer and it will not remain sharp for long.

Get yourself a good mill bast-ard file and learn to use it correctly.

That's where a flap wheel comes in... it creates a lot of airflow, making it MUCH easier to keep blade cool enough.

 

[turbodog]

Trying to think this through, I know that in Ford's, the idler pully is usually a left handed thread. One can look at the direction that the pully rotates when the engine is running. If the fan belt turns it counter clockwise, that would be the direction that would tighten the bolt (if it is a left hand thread), and vice versa.

I believe the picture below is accurate. And if so, then in order to loosen the retaining bolt, one would need to keep the blade from rotating in the cutting direction, while trying to loosen the bolt.

View attachment 44071

If you've got a single blade push mower, it's normal threading. Don't overthink it.

All my mowers, single blade, dual blade, and tri blade are all normal threading. This applies to blade bolts, idler pullies, and so on.

They are not going to sell a consumer device w/ reverse threading. Everyone would break off the bolts, creating a warranty return nightmare. Additionally... it's not needed.

Disconnect spark plug, wedge your tennis shoe into the blade/deck gap, and unscrew the bolt. Pull handles are handy...

While you're under there, clean the deck.

 

[knucklegary]

Once a year, or so, I'd visit local lumber yard and fill truck bed with scrap lumber 2x4, 2x6, "mill ends" from scrap boxes next to saw mills.. The wood blocks are used for kindling, but comes very handy when you need to block-up, or wedge into, pound onto, etc..

Personally, I like using a 12" mill file with mower blade secured in a large machinist vice. Using file correctly removes a minimum, controlled, amount of metal.

 

[orbital]

+

angle grinder
Been leaving my blade on when sharpening vs the bench vice setup I used to do.
Little tricky on getting the right angle, but it saves time. Able to get the angle because I custom lowered my blade.
In doing so, I can have the deck higher & not 'plow' the grass as much.

Lawnmower blades just need to be reasonably sharp, it's not a chefs knife.
Sharpen mine at least once a year.
(I mulch & grind up leaves, sticks, whatever, on my well used brushless unit)

 

[Poppy]

Mine is a 30 inch Honda ride on. It has right hand threading. I used a 1/2 inch drive breaker bar and a good amount of muscle to break it free. I tried it last year, with enough force to make me consider that it might be a left hand thread.

So, blade in hand, with some light cleaning up against a fine grit grind wheel. It cuts, once again, like it should.