Lawn mower blade.... any point in going beyond a simple grind?

A weedwhacker can cut effectively with a "blade" completely circular in cross section. No edge at all.

I wonder how a blade of grass cut roughly is really any worse than a blade cut cleanly.
 
shecky said:
A weedwhacker can cut effectively with a "blade" completely circular in cross section. No edge at all.

I wonder how a blade of grass cut roughly is really any worse than a blade cut cleanly.
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Well, if cut with a dull instrument, the end of the blade of grass is torn...shredded. I haven;t done any experiments, but I have witnessed and experienced what Jerry Baker says. That is that the shredded ends of grass die, giving the lawn a brown look, and it also makes them susceptible to diseases.

A scythe usually has a flat blade and a long, steep edge. By steep I mean long and low....like a knife with a 10 degree beveled edge. It's designed to cut vegetation with the minimum effort possible. It just seems to me that a lawnmower blade edge should be chisel-ground and reasonably sharp.

It doesn;t matter if you try not to run over things with your mower or not (well, yes it does to blade and mower longevity), but the blade will get nicks and dull even if you stay in nice soft grass. This is because there is sand and small rocks that whir around in there.... at least here in the desert southwest, where wind blows sand into the yeard that gets sucked up by the mower. Plus, in my yard (I have an acre and a quarter) there are always a few bare spots I'm working on and sometimes it's impossible to avoid them.
 
The information attributed to Jerry Baker is correct; shredding the leaf blade rather than cutting it is bad both aesthetically and for the health of the turf. Don't go by how the edge looks when you buy a new blade. A lot of them are shipped in bulk and the manufacturer doesn't sharpen them so the edge doesn't get beat up in shipping. Commercially, the first thing you do with a new blade is sharpen it. We do ours chisel ground. (FWIW, Almost 30 years of experience in the hort and commercial landscsape business.)
 
LOL what a thread. Thanks guys. I think I have an idea for myself. I'm going to pickup another blade and try a few different things.



oh yeah... don't mention things like this to your wife. I mentioned to my wife I was going to try a few different types of edges on the lawn mower and it has really confirmed I'm insane. I was stroping a razor when I told her so that prolly didn't help.
 
the possum said:
It may cut as well as a dull chisel sharpened blade. I don't see any way it could cut like a blade that can easily slice paper.
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Most people don't know what sharp grass blades feel like. They are used to mowers tearing grass apart. Anyone who has used manual equipment will tell the difference immediately. The only reason to actually run a corner on an edge is on something like a metal cutting tool where a full sharp edge will break off immediately, so you draw the 0.1 micron edge back to 1-10 microns depending on the tool and what it is cutting. This edge will then be more stable in use than the fully sharp edge because that will microcrack and wear past 1-10 faster than the preblunted edge which is carefully and evenly flattened/rounded. Shovels for example, or large crash axes can be sharpening like that as well.

-Cliff
 
Mine take a beating and I usually wait way to long. When I get to it, I just do a quick gentle pass with a 4" angle grinder. I aim for a chisle grind but don't try to finish it to a perfect edge. As others have said, having a "flat" 1/16" or so doesn't cut better but it will stay "kind of" sharp longer (in tough environments). Most of the time I don't even take the blades off. In some areas of the blades I have to sharpen the flat bottom because of damage. If I wasn't mowing sticks, roots and rocks then I would go for a perfect chisle.
 
Well, the reason a 1/16" "flat" stays "sharp" longer is because it isn;t sharp in the first place. Anyway, you can still chisel grind the edge by just grinding on the beveled edge then flip the blade over and smooth the flat side with a file...just enough to get the rolled edge off. I don;t worry too much about the nicks in the blade, there just doesn;t seem to be anyway to prevent them.
 
I use a batt op Dremel with a sanding drum on it. couple of light passes over the blade once or twice a season keeps it sharp almost all the time. Less than one minute and done.
 
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