How sharp is too sharp? Sharpen new blades?

[Surestick]

Here is something that will mess with your mind but try it. Sharpen your blade, be it 30 degrees or razor sharp. Stand the blade straight up and run a grinder/sand disk lightly over the sharpened part of the blade. This will result in a squared off cutting edge which then creates 2 cutting surfaces instead of 1 if sharpened in the "Traditional Way". This will create an "edge" that will last a long time and will cut your grass like no other. Try it out and let me know.

This is how a lot of blades are sold new.

 

[97prizm]

As the title suggests, how sharp is ideal on a lawn mower blade? Does anybody sharpen new blades?

I use a sharpener stone on a drill. It's set at the correct angle. I make a couple of passes to give it a relatively sharp edge but not razor blade sharp.

 

[yeehaw1960]

Good luck trying to do this! It is much better to pony-up for a replacement blade if you bend it.
Also, if you hit something hard enough to bend the blade you need to check the blade adapter, the crankshaft (for straightness), and the flywheel key.


You can't balance a blade this way. A proper blade balancer only costs a few dollars and can be purchased almost anywhere (Walmart, Home Depot, Lowes, Ace, True Value, Amazon, etc).

The little cone shaped blade balancers don't do any better than the old 'nail in the wall' if you can see to center things. Many blades don't have a round hole in the middle anyway. Bending a slightly bent blade end (1/4 inch or less) is relatively simple if you have a bench mounted vise to hold it while you tug at it. I don't sell balancers or blades, so I don't have any skin in the game. When I happen upon a 'champion', potentially competition-bound blade that will be scrutinized and scored by a panel of judges I might feel different. My way works just fine four or five times a day, each and every day all summer long. It's kind of like I tell people about mixing two stroke fuel. I go with 40 to 1. Many things call for 50 to 1, but unless I'm going to race a chainsaw and rebuild the top end ever four hours, 40 to 1 is a pretty reliable mix ratio. A plug every couple years, and a youtube tutorial on how to clean the exhaust's screen might be in my future, but I like to error on the side of caution.

 

[yeehaw1960]

Sharper is better for grass. But if you have twigs, small rocks or other debis, sharp thin edges will form gaps and become dull faster.

I like it when I flip a mower on it's side (after getting it running) to drain the oil, and I find a new blade installed upside down. I can then inform the customer that their blade is new for the second time.

 

[BHopkins]

I never sharpen a brand new blade. It just blows my mind when I hear people say that do that. As has been pointed out here, a mower blade doesn't stay sharp for very long. So no need to obsess about a razor edge.

 

[Ducati996]

I’ve read/heard that blades should be blunt not sharp.
Here are my thoughts;
1)
Is there engineering data to support this opinion?
2)
If we sharpen a blade to a sharp edge like a knife it will blunt (round over) rather quickly and resemble the blunt edge which the (experts) prefer.
During this blunting process the sharp blade is cutting grass like a new razor cuts your whiskers! So wouldn’t a blade with a knife edge cut more grass before it requires attention?
It starts sharp then (blunts) similar to a new factory blade, wear stabilizes until it rounds over.
3)
How are you going to duplicate the factory edge on a used blade?
Blades don’t wear evenly they taper out to end so the only thing you can do is grind it to a sharp edge and call it a day.
4)
I use my blades until the lift and ends erode while always checking for fatigue cracks.
I sharpen them when they no longer cut cleanly and bog the engine down.
I also balance blades every time I sharpen them.
5)
I agree with a previous poster that said perhaps a sharp blade is a liability!

90cummins