He's exactly right. I had a section of my property that was sand and had some wild grass that I would cut. More sand than grass. I took the blade off to get a 2nd one, and thought it was the wrong one because it was missing the two cut outs. My blades would last 4-5 years, tops on my Lawn-Boy.

This is normal wear on the 'lift' foil on blades, and is what sends most hi-lift blades to the trash can. When the foil gets to 1/16" at the thinnest area, it is off my mower and in the trash. I do not want pieces of that foil leaving my mower at 300 feet per second. Yes, it happens fast in sandy soil, but just cutting too close in regular soil will also do it, as well as mulching up leaves which have a fair amount of grit on them. Fortunately for all of us, mower blades are VERY ductile steel and tend to not shatter or break into pieces. Even so, when that foil gets too thin it probably would break off if you picked up a fairly good-sized rock.

{{gwi:128512}}

This is pretty extreme but if the split is what you have, yes to what the others have said. It's called sand blasting but doesn't need sand. Any kind of dry dirt will do it. If you ever get into a cloud of dust, this sort of action is happening to the blade.

This doesn't happen with one mowing but it is conceivable it was badly worn and ready to be opened up when you were working on it. The last heavy debris mowing just washed out what was probably foil thin metal.

The blade pictured is an extreme example for sure! Also, notice that the blade is sharpened improperly. Instead of taking the edge back into the blade, all manufacturers recommend angling the cut so the blade loses no width at the start of the edge. Once the blade gets down to 1" wide at the end, not counting the lift foil, the blade is to be removed. Of course, by that time the lift foil is going to be long since worn out anyway!

Thanks for the replies. I do use the mower in lieu of a vacuum on hard surfaces around my home - ably takes the place of a separate vacuum - set deck height to lowest setting with bag in place. Very effective. Perhaps there is some grit on the street when I pick up my cuttings, or on my driveway.

I definitely have some shaded out areas where little grass grows, but many leaves fall.

I wonder why I never saw this sort of wear on my three-blade 42" Yardman Rider (same vintage as my LB).

Anyhow, given a choice, I'll keep on using the mower the way I do and just plan on replacing the blade every (uh-hum) 20 years or so. That should do it.

Caruso

I have a 42 inch Troy Bilt Bronco lawn tractor.....I have been cutting almost 3 acers for about three years. I have to replace a blade after cutting the grass three times....the blade gets sand blasted until there is nothing there. That is a little tractor for as much grass I am cutting......I'm fixing to order a bigger one.....Troy Bilt Super Bronco XP 50 inch cut. If I only had to replace the blades once a year, I would be a happy man with a thicker wallet!

Again, it is normal wear and happens with or without sand or dirt abrasion. It just happens quicker under some circumstances, so all mower users need to look for it when servicing the blade or getting under the mower for any other reason.

In some applications there are sand blades available aftermarket, such as OEP. They are ultra low lift blades that do not generate near as much air flow . Obviously, no good for bagging. Cheers to 2008 :)

Funny he described it as a Nike Swoosh. Both the blades on my John Deere Z 345 have the same wear pattern on the ends. I do have a lot of sand on the 3/4 acre I mow but I was surprised there was this much wear after only six or seven mowings, although I do also drop the deck down and use it as a vacuum on my large driveway. And these are not even high-lift blades. If the photo isn't showing, the wear is a big cut-out that is shaped like the Nike Swoosh and it is on the corner opposite the cutting edge on each end of each blade.