Let's talk about blade sharpening?

garyoldfart

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LOL... the subject is controversial, but the 30° seem pacified...


At least you could see how the profile of the sharpening is, which depends on the damage.
Here is the way to sharpen:
 

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CaptFerd

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A sharp lawnmower blade is vital to get the job done good an proper
 

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ILENGINE

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Have seen new blades without the fine sharp edge, which does not last long at all. Maybe so the new owner does not cut hands when putting them on. Would you know the reason?
Oregon blades which also make a lot of OEM blades sharpens them to a 30 degree angle leaving the recommended .030 blunt edge and then they are painted which makes them appear even duller.
 

clarkoh

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I would disagree with that one. Usually mower blades, well, OEM mower blades are made of inferior steel. From what I've used Oregon has the best steel.

I would say used truck leaf springs would be a better choice.
Good Point. Leaf springs are great source of tough, hard steel. We have made slap hammers for body work and they are very resistant to deformation and hold their shape.
 

Grum

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I sharpen mine on a bench grinder and spray them with water from a squeeze bottle to keep them from over heating. I used to balance them on a nail but lately I’ve used one of those aluminum cones. Works for me.
 
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Retired blades make good knives. Cut to rough shape, flatten, grind to shape, sharpen, drill and make handle.
Oh hell yeah!! The right combination of tensile strength, and metal composition.. They make a great bushwacker! For real fun, try a large file..
 

woodstover

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Really good post. I think the 45° is a little steep. I personally sharpen mine to 30°ish. All the new blades I've ever bought have an initial grind of about 30° so that's what I've stuck with, they seem to stay sharp quite long.
 

TobyU

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Before I even read the replies I'm going... Let's not! Let's don't even bother to talk about it because no one is ever going to agree on it and there no real consensus since brand new blade manufacturers will sell you a brand new blade in different types of sharpness, coated/dipped and paint, or not extremely sharp to begin with.
If there was one right or wrong way you would assume that by now the manufacturers would have all gotten on the same page and that's how they would come when you buy a replacement blade but it's not the case so everything else is simply going to be personal preference and then reality it makes little difference.
So much so that I get multiple mowers in every single year with the blades on upside down and the customers had no idea!

Now, I'm a lot more repair guy and not a landscaper so I fixed them but I don't use them but even I in my total disregard or care for lawns and grass can usually spot grass that's been ripped apart or roughly jaggedly chopped as opposed to cut with a somewhat sharper blade but the fact is most people can't tell the difference.
That thin piece of metal is spinning so quickly that whether you want to argue about 45, 33, flat spot on the very edge, or sharp as a razor, it's going to make very little difference and anyone who thinks they can tell the difference I could set up a demonstration and I guarantee I could fool you among 20 mowers.
So as I said, I guess it's fun for conversation but let's not worry too much about it.
 

TobyU

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Now after reading most of the replies I'm going to say I'm glad that most people realize it's not that big of a deal.
Those of you who are going to insist that some commercial blade bouncer is really necessary and it makes a real difference or any other thing like cleaning off the blades and bead blasting them painting them etc... I just want to know exactly how much time do you guys have??

Are you doing this professionally or just as a hobby and don't even do two or three a week?

It's pointless to clean up the blade because typically it has about the same amount of buildup on each side so the balance rains the same and it's just going to build up again.
I mean, you can knock the most of it off with one little push of a scraper putty knife or something on each side but going beyond anything past that it's just a waste of time.
It might make you feel better, or superior, but it's still a waste of time.

This is why I said my other post let's just not because it's just a contentious opinionated argument and we're never going to solve anything.

Now the more important thing is how many times you can sharpen a blade or when you need to replace one.
Generally you can sharpen a blade at least three or four times if not four or five times plus before you have to worry about it but that is entirely relative to how much knowing it's done between sharpening and how much each sharpening takes off.

These commercial shops with the high end grinders are kind of like production and they don't worry about whether the blade is pretty sharp to begin with OR beat the heck. They just swoop it across one to three times and eat off a lot of metal. The same reason lots of people don't want those shop shopping their chainsaw chains.

Anyways, eventually the blade will get cut back from its straight edge like in one of the pictures and while that is not the worst thing in the world it still can affect the quality of cut and the power in inertia some so when it gets cut back to where it's pretty noticeable like coming up on 3/8 to a half of an inch it's probably time to replace but fortunately it usually works out pretty well because the most important thing is when the back of the blade gets thin or it starts to crack on the little airfoil
bend.

The back non cutting Edge the blade is typically the thing that makes you have to replace the blade before the cutting edge! I know it makes no sense but that's just the way it is.
It will get razor blade thin and start to wear off the back edge and often crack with a little bend is which can allow pieces of metal to blow around which means the blade needs to be replaced.

There has been a general rule of thumb about the 30° versus 45 as in one gives a better quality of cut but doesn't stay sharp as long and the other one vice versa. I think the Honda twin cut system kind of goes for this effect. I just continue to sharpen the blades at the angle they come from the factory but I believe the Honda has one sharper angle and one lesser angle so they're trying to get the best of both worlds with their two blades.

However, oddly enough, I don't find that Honda's have the best quality of cut! They often leave stragglers and the overall quality isn't as good as some other mowers with simply one blade.
I think deck design has far more to do with it than blade and and blade design has more to do with it than sharpness.
 

Ray52

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I've been clamping my blades and using a side grinder and large file for years. I'll grind or file the cutting edge flat with the bottom of the blade, and grind an approximate angle of cut, close to the original angle.
This general method has allowed me to get a clean, smooth cut every time. IMO the slightly flat edge on the cutting tip allows for force dispersion on the blade allowing the
 
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