years ago while working in maintenance one of the employees who mowed around the plant for extra money complained to the boss in front of me that the mower blades was dull . i told him the blades didn't need to be really sharp . he went on about how it didn't cut good . i said ok tell me how do you sharpen weed eater string . end of conversation .
- Thread starter bill b va
- Start date
A friend who has been in the lawn mower business all his life and owns a dealership instructed me NOT to sharpen a lawn mower blade fine and razor sharp as its edge will turn/roll back to easy and not cut as well, but rather just give it a smooth even semi sharp tapered down finish (like what new factory blades look like) and that seems to work best and stays decent all year long.
John T As usual, sharpen them however you please, I'm only sayin what I heard and seems to work great for me, may not for you.
John T As usual, sharpen them however you please, I'm only sayin what I heard and seems to work great for me, may not for you.
John, having been in the business for 25+ years, I agree with what your friend told you.
However, paying customers expect to see a very sharp blade or they feel cheated.
Disturbances in the cutting edges are what reduce the quality of cut.
The angle of the cutting edge must be a compromise. ...Too shallow an angle dulls quickly and is easily damaged, while too steep of an angle does not cut grass cleanly.
However, paying customers expect to see a very sharp blade or they feel cheated.
Disturbances in the cutting edges are what reduce the quality of cut.
The angle of the cutting edge must be a compromise. ...Too shallow an angle dulls quickly and is easily damaged, while too steep of an angle does not cut grass cleanly.
MarkB_MI
Well-known Member
- Location
- Motown USA
Brand-new blades aren't rounded off; I assume the manufacturer knows the best profile for its blades. They will cut when dull, but they don't do as nice of a job.
Heavy string trimmer line doesn't have a round profile. Each manufacturer has its own proprietary profile, but they all have sharp edges to effectively cut grass.
Heavy string trimmer line doesn't have a round profile. Each manufacturer has its own proprietary profile, but they all have sharp edges to effectively cut grass.
Texasmark1
Well-known Member
Originally it was round but time proved the sharp edges were necessary as were different chemical formulas for the "string".
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While answering the subject, could be several reasons for new blade shapes, one being resistant to chipping with more material present on the cutting edge, and then some also have a heavy coating of baked on paint which has a dulling effect. I do know that a sharp blade does matter when you want a freshly mowed lawn appearance to whatever you are mowing.
On my mowers I remove the blades and usually use a 4 ?" grinder for the sharp edge. On the hogs, I leave them on the machine and grind them off sharp. I do not mow other's property and mine is clean; no rocks, no debris.
On my hay cutter, which is a drum mower, I have 6 bidirectional blades on each drum and rather than replace with new blades which are blunt as others have mentioned, I just take the same grinder and while in place clean up the cuting side. Really makes a difference in a clean cut on soft grasses like Coastal Bermuda or Rye.
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While answering the subject, could be several reasons for new blade shapes, one being resistant to chipping with more material present on the cutting edge, and then some also have a heavy coating of baked on paint which has a dulling effect. I do know that a sharp blade does matter when you want a freshly mowed lawn appearance to whatever you are mowing.
On my mowers I remove the blades and usually use a 4 ?" grinder for the sharp edge. On the hogs, I leave them on the machine and grind them off sharp. I do not mow other's property and mine is clean; no rocks, no debris.
On my hay cutter, which is a drum mower, I have 6 bidirectional blades on each drum and rather than replace with new blades which are blunt as others have mentioned, I just take the same grinder and while in place clean up the cuting side. Really makes a difference in a clean cut on soft grasses like Coastal Bermuda or Rye.
There ya go! I never have crawled around on my hands and knees with a magnifying glass to see how clean a blade of grass was cut.
I bought my first power mower in the 1960's and that was the way the dealer showed me how to sharpen the blades. He said if you try to keep them section blade sharp the blade won't last long until you will need to buy another blade.
I bought my first power mower in the 1960's and that was the way the dealer showed me how to sharpen the blades. He said if you try to keep them section blade sharp the blade won't last long until you will need to buy another blade.
Russ from MN
Well-known Member
- Location
- Bemidji MN
One reason a lot of new blade aren't real sharp is to reduce liability if someone cuts themselves. Remember, everything has to be idiot proof!
Steve@Advance
Well-known Member
Russ, I agree, the blades are left somewhat dull to not only protect the consumer, but also the employees assembling it at the factory, and those handling it at the retail store.
It is also much faster, cheaper, and easier to leave a machined edge than to add a second opp for grinding.
It is also much faster, cheaper, and easier to leave a machined edge than to add a second opp for grinding.
End of conversation??? Weed-eater head can be turning 10,000 RPM. A mower-blade often only turns around 3000 RPM. Sharp blade certainly makes a difference in quality of cut. Some rich estates would fire a landscaper who mowed with a dull blade that broke the grass instead of cut it. There was a law passed years back that limits the blade-tip speed of a mower to 19,000 feet per minute. I remember when it happened, all our 21" mowers had to get the engine governors adjusted so they ran slower. 3600 engine RPM was not allowed anymore with a 21" blade.
What I do is clamp it to the side of my back porch. Use an angle grinder with a sanding disk on it. Use 120 grit.eDo my blades every other mowing. I mow a couple of lawns around the neighborhood. I have two or even three sets per machine. Just chain hoist the machine up and ZAPP with the air gun. Sharpen when I get around to them. Now I check the square of the edge with a square . If not a perfect 90* I grind the edge back just a little to true it up. Next I use the sandpaper disk to gat just a bit more than a 45* edge. Kind of a ZEN thing as you grind. Take one of those little cone shape balancer things that allows me to balance the blade side to side and end to end. Works beauty! In all of the years of mowing I have needed to replace only one set of blades. Another thing I have brought up on here is the use of "SAND" blades. They have a very small amount of lift. Just barely throw the grass from the deck. What the good point is your deck doesn't get the crap beat out of it.
Moonlite37
Well-known Member
It is not the RPM it is the FPM, A weedeater string has less circumference than a lawnmower blade and this has more RPM
And as I said - a weed eater with a string rips grass instead of cutting it, just as a dull mower blade does. And speed? A weedeater head with 8" of line run at 10,000 RPM has a tip-speed of 42,000 feet per minute. A 21" mower blade at 3100 RPM has a blade-tip speed of only 17,000 feet per minute.
Gene Davis (Ga.)
Well-known Member
When you think you have built it idiot proof,idiots just get smarter!
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