So for the whole year I have been wondering why my TTTF grass blade tips were brown after a mowing, even after the blade was sharpened right before said mowing. I thought maybe it was a nutrient deficiency, or disease of some sort, but it was occuring only thirty minutes post cutting. Finally I looked at my blade. I have a mulching blade. The ends of the blade are at an angle to the axis of rotation, probably 25-30 degrees. When you sharpen the blade you leave the bottom of the blade flat, and grind the top of the blade to about 30 degrees. Now when the mower is rotating the blade the sharp edge is not contacting the grass blades first due to the angled end, and the angled sharpening, it's the upper flat part that meets the grass first, then the sharp edge tears the blade. So what I did what sharpen the blade in reverse, i.e. beveling the bottom, and leaving the top part flat. This way the sharp edge is the first to make contact with grass, cutting it instead of tearing it. Since I made the change the brown tip problem has essentially disappeared. Hope this helps with people having the same problem. I included a crude diagram to help show this. The horizontal line is the axis of rotation, the end of the mower blade has a red line showing the new sharpening angle, the green thing is obviously grass.

I noticed my grass tips are brown too and it's very obvious that my blade isn't sharp. I'll sharpen it hopefully next week.

Thanks, I have to try this as I have the same setup on my blades!

I did note that it's worse in hot weather, so some of it's thermal damage to the tip. Unsurprising, I guess--grass dislikes bleeding when it's hot and water is limited.

s1mpl3k1d wrote:I noticed my grass tips are brown too and it's very obvious that my blade isn't sharp. I'll sharpen it hopefully next week.

Is it that it's not sharp, or is it that the blade is angled too much to present the grass with a sharp edge? If you have a mulching blade, hold it up to your sight line, looking at one of the ends, while the center of the blade is parallel to the ground. If the sharp edge is pointing down, you might have to reshape your blade.

Tips will turn brown after mowing in times of direct, close sun and high heat because the leaf is not succulent enough to recover and repair from the damage and stress of mowing. Click here for more information

During heat spells like we currently are seeing, irrigate the day before mowing (later in low sun) and then the leafs will contain sufficient moisture to repair themselves.

I agree with you Gary, but this has been going on for the whole year, even in spring. Closer inspection of the blades shows a ragged edge, one you would expect from a very dull blade, a tearing action instead of a cut. Reverse sharpening gives a much better cut with my blade, and should reduce some stress on the grass.

What I don't get in your picture is that the blade is at an angle. On my machines, the blade is parallel to the floor and angles up toward the back for lift. The conventional sharpened edge contacts the grass first.

All blades aren't made the same I guess. My blade's edge isn't parallel to the ground when the center of the blade is. It is a replacement I bought this year, so obviously it's made as cheaply as possible and apparently no thought went into the design. Next time I sharpen it I will take a pic to show you exactly what it looks like.

The above are gator blades but my OE John deere blades sit the same way. The sharpened edge always leads.

Those are nice, with the blade I bought the leading edge doesn't flatten out like those gator blades.

tiemco are you sure you don't have the blade installed upside down? You wouldn't be the first here to do it, LOL.
That would beat the he!! out of the grass causing it to brown rapidly as you describe.

GaryCinChicago wrote:tiemco are you sure you don't have the blade installed upside down? You wouldn't be the first here to do it, LOL.
That would beat the he!! out of the grass causing it to brown rapidly as you describe.

+1. I honestly have never seen a mower blade that wasn't lying flat at the cutting edge.

GaryCinChicago wrote:tiemco are you sure you don't have the blade installed upside down? You wouldn't be the first here to do it, LOL.
That would beat the he!! out of the grass causing it to brown rapidly as you describe.

I didn't think of that, but I know that if you install a blade upside down, it does a poor job of cutting, shreds the leaves and turns them brown in a big hurry.

Not that I've ever done it. I think I must have read it somewhere.

Yeah, that's the ticket.

Ha ha, I already thought about that and checked to be sure I have it on correctly a while ago. I will supply a pic sometime this weekend.

I notice the brown tips as well even after a freshly sharpened blade. The shape of my blade is curved, something like this (though mine is sharp)

Click here for more information

vs something straight

Click here for more information

is there a difference in the cut vs the shape

Wow, that blade in the first pic, which I'm assuming is your's, needs to be reground, or thrown away. The reason you have brown tips is because that blunt edge isn't cutting the grass, but slamming into it and tearing it. The blade in the second pic is what it should look like, the leading edge parallel to the axis of rotation, then the back half bent at an upwards angle. Mine has no bend, it is all the same angle not parallel to the ground, as illustrated by my crude drawing, which is looking at the end of the blade.

oh, that's rich! that blade looks like it came off my rider after the destruction derby, hehehehehe.
grind(4" angle grinder) the nicks out, get with the angle and sharpen a few passes(in a vice not on the mower!), then take a file and finish the job. put the blade on a balancer and correct out of balance. if you have elite KBG, finish the sharpening with a cork and cigar ashes. then again, throw the old POS blade in the garbage and get a good one for next season.
Click here for more information
(only info I have on sharpening a reel mower is to send it to that old guy that knows how to do that).

look at this, floow saftey directions--
Click here for more information

LoL its NOT my blade, as I stated, its just the same "shape" because it has that curve to it.

That's like the only picture I could find, I guess it's an obsolete blade design. Seems like most of you all have flat straight blades (and with better performance)

OK, so here's my blade. Sorry the pic is so grainy, it was better without the flash. I took this with the flat center part of the blade level with the lens. It is an end on shot, you can clearly see that the blade angle is 25-30% off from horizontal:



Probably going to scope out the replacement offerings at the Depot this week, as this blade also makes so much turbulance that leaves are often pushed out from under the deck before they are chopped/bagged.

Yeah, that is a weird design. Hopefully they'll have a replacement for you. What kind of mower?