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I know that there are probably as many threads on here on this subject as any other. I also know many people have differing opinions.

We normally see blades run about 6 to 7 hours before they are really not cutting any more.

I bought a new Scag Tiger Cat and it has a little over 7 hours on it now and the cutting edges on new factory blades are pretty much gone and are going to have to be sharpened.

Is this comparable results that any of you are seeing?

Of course they will still cut but the quality of cut is no where near what it should be.

Some of you guys that run hard give me some input on your experiences.

How long is a piece of string.
200 hours cutting bench or couch grass will not even take the paint off the edge
2 hours of thich tufting grasses will render the blade blunt and we have not even started talking about stick , stone , sand & gravel.

Once the blades start to loose their edge the wear increases in an exponential rate which is why people who sharpen daily with a diamond hone /oil stone get a lot longer life out of their blades.
Counter intuative I know , remove metal more often and the blade lasts longer but that is how errosion wear goes.

jekjr said:

I know that there are probably as many threads on here on this subject as any other. I also know many people have differing opinions. We normally see blades run about 6 to 7 hours before they are really not cutting any more. I bought a new Scag Tiger Cat and it has a little over 7 hours on it now and the cutting edges on new factory blades are pretty much gone and are going to have to be sharpened. Is this comparable results that any of you are seeing? Of course they will still cut but the quality of cut is no where near what it should be. Some of you guys that run hard give me some input on your experiences.

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I sharpen my blades daily. They are just a wear and tear item, so when they need to be replaced I just buy a new set. I would rather buy new blades than try to run a set as long as possible between being sharpened. But to answer your question yes my blades need to be sharpened after about 6-8 hours of use depending on the days conditions to maintain a clean cut appearance.

I also change blades out every day. About 8 hours.

i also run tiger cats with Scag blades most everything up here is blue grass or tall fescue. so we sharpen about every 10-15 hours of run time. the blades seem to be pretty decent and keeping the angle is the most important thing just knock the Knicks out. razor sharp blades will dull in 10 minutes and erode the metal more quickly reducing the blade life significantly faster.

I have no specific time frame I sharpen when they need it. When the grass shows signs of tearing instead of having a nice clean cut, it's time to sharpen. If your running multiple mowers blades tend to last a lot longer without sharpening.

Ric said:

I have no specific time frame I sharpen when they need it. When the grass shows signs of tearing instead of having a nice clean cut, it's time to sharpen. If your running multiple mowers blades tend to last a lot longer without sharpening.

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I guess that's what I was trying to say, thanks for helping me articulate my end state.

TaskForceLawnCare said:

I guess that's what I was trying to say, thanks for helping me articulate my end state.

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How often you should change out blades or sharpen depends a lot on the type of grass you cut and the conditions you're cutting under. The average homeowner should start out the season with a new blade or good set of blades and can get by sharpening half way through the season. The commercial guys can get by sharpening two or three times a season with purchasing the right blades for his mower and most of them are going to buy the good heavy duty blades.

I'm surprised how dull a new blade is. All the ones I have seen you can press your finger on it and run it without worry. When I buy them I do sharpen them when new so they are sharp. I am just a residential mower with a push mower. So it might be different for you guys running the fun big machines :wink:

OutdoorEnvy said:

I'm surprised how dull a new blade is. All the ones I have seen you can press your finger on it and run it without worry. When I buy them I do sharpen them when new so they are sharp. I am just a residential mower with a push mower. So it might be different for you guys running the fun big machines :wink:

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The blades really are not dull.
They are dipped in a heavy paint.
Why you ask? So that when a person that is careless installs the blade they do not cut them selfs.
They are as sharp as they need to be.

Carscw said:

The blades really are not dull.
They are dipped in a heavy paint.
Why you ask? So that when a person that is careless installs the blade they do not cut them selfs.
They are as sharp as they need to be.

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I asked because I thought maybe the paint was more to protect it from rusting in storage until it's sold or something. I was just surprised that a new blade isn't very sharp.

Now to get a little exoteric, there is nothing that is really sharp, they are just less blunt.
The actual thickness of the leading edge is a compromise between thickness which is needed to support the blade and thinness which improves the cutting rate & finish.
Too thin & the edge will chip dent and dull very fast.
Too thick & it puts a greater load on the engine and bashes the ends off the grass.
For push mowers some where around .040" tip diameter is near ideal.
It used to be thicker but the maximun permissible blade tip speed is continual being reduced in order to make mowers more safe ?

On the residential machines, I grind the edge to a sharp by feel edge. The blades spin slower so it helps the grass look and motor run with less torque. I do these once a year when I do the full service on them.

On my Scag I run it on my property and neighbors yard so it gets several hours a week. In the fall it works a lot harder but still a fraction of use compared to a dedicated lawn care business. I sharpen the blades almost as sharp as the residential machines and they also get done once a year after the fall clean up is finished. They look good but I still grind them some to keep the edge as I like them.

So to a machinist eye I grind the residential blades to .005 thousands edge and the big Scag to .020 thousands edge. Mostly blue grass here, a few rocks. I cut at 4" level to avoid the rocks and tree roots as much as possible.

I'm guilty of sharpening new blades out pf the package also....:laughing:

Those edges are a bit on the fine side but obviously work well for you.
I wish I could get you to talk to some of my customers who insist on mowing their grass at 1/2 with a rotary mower .
For those who need to cut that low they make drum mowerers.

At thoes heights you are obviously getting away with the fine edge and your lawn should look & feel great.
The finest edge recommended by any bar blade maker is 0.125 ".

With the grass too short you just burn the grass in the summer. I don't water my grass and it stays green all summer long, unless we have a super hot dry spell. I started striping the yard and it's nicer when the grass is longer also.
Third, the blades get destroyed when they hit hard stuff...Sharpened blades get all bent, dinged up. I finally wised up after all these years and raised the deck:laughing:!