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I bought new blades for my JD 42" deck. They appear to be dull as a rock. I am used to taking the blades off and putitng them in my vice and using a flat file to sharpen the old ones. From what I read, the new dull blades should be used as is. Was I wrong in sharpening the old ones the way I did?:confused2:

I don't know, but I'll be watching this thread for opinions as well. I've always done the same as you, file and vice, just sharpened my push mower blade yesterday.

gtlhd07 said:

I bought new blades for my JD 42" deck. They appear to be dull as a rock. I am used to taking the blades off and putitng them in my vice and using a flat file to sharpen the old ones. From what I read, the new dull blades should be used as is. Was I wrong in sharpening the old ones the way I did?:confused2:

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I always knock the paint off the cutting edge on new blades. Probably not necessary but I do it anyways.

i usually sharpen my blades so they cut as close to a scissor cut as possible(like a reeL mower shears the grass blades).....i can pluck a grass blade from the yard after i just cut with a dull blade and then sharpen the blade to a razor like edge and then pluck a grass blade from the razor edged blade cut and the difference is awesome, it looks as though you cut with a set of hand shears,and it is healthy for the grass and doesn't leave a brownish tint looking over over the lawn because there are no scraggily grass blade ends .doing a sharpening like that takes time,plus my yard is medium thickness

It appears this is a new design someone is trying. Are they JD blades, or an aftermarket brand?

My dad always told me never to make a lawnmower blade knife-sharp - just take out the dings.

But, brand - new blades from Snapper or JD (for my Deeres, anyway) are sharp enough to shave with - so I discarded what he always said, and dress them once a season to the knife edge they came with new. (maintaining the same angle)

But, if yours CAME dull, it is probably in the design, and I'd leave it (and dress it next year) that way. Unless you got a blade that someone forgot to sharpen. :wink:

Take a pic of them before using them, so you have a reference to how they are ground, and/or draw yourself a 'profile' pic.

Depends on the cutting edge alloy & temper... Older blades were softer steel, if you made them razor sharp the edge would just fold over.
So if your blade is soft enough that you can easily sharpen it with a hand file... don't make it too sharp, leave it with a 1/16 wire edge...
If it is hard to cut with a file make it sharp, the edge will not fold over, it might chip but grass will not hurt it... :smile:KennyV

KennyV said:

Depends on the cutting edge alloy & temper... Older blades were softer steel, if you made them razor sharp the edge would just fold over.
So if your blade is soft enough that you can easily sharpen it with a hand file... don't make it too sharp, leave it with a 1/16 wire edge...
If it is hard to cut with a file make it sharp, the edge will not fold over, it might chip but grass will not hurt it... :smile:KennyV

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Aren't most mower blades spring steel (as in leaf springs)? Otherwise, they'd bend at the slightest obsticle. That would have something to do with it. Although, there are MANY grades of 'spring steel', as you mentioned.......

not sure if it makes a difference, but when i file dress it to get that razor edge i start at the 'sharp edge' and file toward the wing and not from the wing to the sharp edge and drag the metal out(if this makes sense) .....hey kenny,would a older cylinder mower blade be of a different grade steel than a new cylinder mower blade?idk

LandN said:

not sure if it makes a difference, but when i file dress it to get that razor edge i start at the 'sharp edge' and file toward the wing and not from the wing to the sharp edge and drag the metal out(if this makes sense) .....hey kenny,would a older cylinder mower blade be of a different grade steel than a new cylinder mower blade?idk

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Thats how I always used a file, and it's the way I use a belt sander, And a good way to stone a knife blade, that is how you strop a razor also...

I don't know but my OLD Torro gang set has incredibly hard blades... I don't know if they have worked hardened over the decades but they sure are hard... :smile:KennyV

KennyV said:

Thats how I always used a file, and it's the way I use a belt sander, And a good way to stone a knife blade, that is how you strop a razor also...

I don't know but my OLD Torro gang set has incredibly hard blades... I don't know if they have worked hardened over the decades but they sure are hard... :smile:KennyV

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They may be hard indeed - but if they are bent, and yoiu clamp them in a vise just below the bend, and whack it with a maul - does it immediately bend? Or does it spring back? :wink:

That's why mower blades are nearly impossible to straighten........and heat wrecks them. (heat wrecks spring steel, too)

twall said:

They may be hard indeed - but if they are bent, and yoiu clamp them in a vise just below the bend, and whack it with a maul - does it immediately bend? Or does it spring back? :wink:

That's why mower blades are nearly impossible to straighten........and heat wrecks them. (heat wrecks spring steel, too)

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It has been so long since I have bent a blade (over 30 years for sure)... I don't recall ever trying to bend one back... I am sure I have some old ones around... I'll have to try... I have welded things back using old mower blades as scrap gusseting material...
If I find an old flat one I will try... I suspect it will NOT bend ...
The cylinder mower blade that LandN was asking about are Reel mower blades... I've never bent one of those but I have chipped some, they are hard... :smile:KennyV

I have put more then one blade in the vice over the years and straightened them by pulling with hand pressure only. now this are the thinner push mower or rider blades that come on box store mowers and not the 1/4 inch thick commercial or heavy consumer mower blades found on name brand mowers.