Can mower blades be hardened?

I'm assuming that new lawn mower blades are sharpened, then hardened before
sold. Question: after sharpening the blades on a bench grinder (after much
use) is it necessary to harden them for longer life, and if so, how?
Thanks.
EW
Reply to
EW
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Only if you "blue grinded" it. If the steel turns blue, the hardening are ruined. So cool it often, an dont overheat. And yes, the can be re-hardened!
The easy way of hardenig is to heat the blade dull red. and throw it in a can of water.
"EW" skrev i melding news: snipped-for-privacy@enews2.newsguy.com...
Reply to
Haaken Hveem
Unless you know the material's metalurgy and are knowledgeable about heat treating I wouldn't chance doing that.
The thought of a too brittle blade shattering and tossing a piece out, even if it just busts a window and not some child's face is just too scarey for me to think about trying that myself.
Personally, I use my angle grinder with the mover blade still on the machine and do my best to hit both ends evenly enough so I don't have to mess with balancing the blade each time I sharpen it.
Jeff
Reply to
Jeff Wisnia
Not likely enough carbon to harden.....
I have never seen a hardened blade. Hardening makes them more brittle. Brittle makes them break. Breaking turns them into shrapnel. Shrapnel is bad......
Reply to
Gene Kearns
And usually addressed "to whom it may concern"!
Reply to
Tm
"EW" wrote in news: snipped-for-privacy@enews2.newsguy.com:
Mower blades are not hardened to anything appreciable. To do so would endanger your (and anyone else who happens to be in the vicinity) life or limbs. My bet is they aren't over 30RC IF that, probably more in the 20's. You want the blade to deform if it hits something, not break. A localized induction hardening with immediate quinch might work on the actual edge, but that still leaves the possibility that the blade would shatter if it hits something, since a crack will form in the hardened area, which may well propagate to the rest of the blade. In a nutshell, leave it soft!
Reply to
Anthony
My dad was a certified pressure-vessel stick welder. Rather than hardening his mower blades, he used to hard-face them with a tungsten rod. The host metal would slowly wear away until there was mere foil holding the (almost) intact tungsten edge in place .
Most commercial mower blades (you know, the really thick, heavy ones, like on Scags, Dixie Choppers, etc) are hardened in and around the cutting edges. The bodies are left at a tougher temper, especially around the hub hole.
LLoyd
Reply to
Lloyd E. Sponenburgh
I regularly sharpen my blades with a file. They are not hard at all.
chuck
Reply to
Chuck Sherwood
Hardening would be a bad idea. One maker does put something like drill tek or borium on the flat side of the edge.(cub cadet) If you want the blade to last longer file or grind a 30 degree bevel and then flatten the very edge to be about 1/32"
EW wrote:
(after much
Reply to
bamboo
Mower blades for commercial machines are hardened at the cutting edges and the hub. Cub Cadet offers hardened blades for the bigger decks from the factory. They work OK but the edges chip easily if you strike rocks. They are also hard to sharpen properly.
Reply to
Steve W.
It also assumes there's enough carbon in the steel to induction-harden. Maybe, but it's probably a medium-carbon steel that may not harden very much anyway.
Maybe I'll do a test on an old blade this summer. I have one that's on its last legs and which could be sacrificed.
-- Ed Huntress
Reply to
Ed Huntress
FWIW, consumer-type mower blades for Sears mowers, and probably for other brands, were hardened until just before 1960 or so, after which they were much softer. I happen to know this because my dad was a Sears store manager at the time and he told me about the toe-cropping lawsuits that caused Sears to change to the softer blades.
Maybe there will be a market for antique, hardened mower blades on e-Bay some day. There's a market there for almost everything else.
-- Ed Huntress
Reply to
Ed Huntress
Yeah... and I'm SURE that flesh understands and reacts positively to the difference between 3000 RPM 'soft' blades, and hardened ones!
Doesn't the CPSC do the dumbest things?
LLoyd
Reply to
Lloyd E. Sponenburgh
Well, originally, Sears et al. were just trying to duck lawsuits. They had several cases in which the mower hit a rock, the blade broke, and somebody lost a few toes.
That's why my dad made me where steel-toed boots when I mowed the lawn. 'Just checked -- there are ten of them on my feet. That's the right number, I think.
-- Ed Huntress
Reply to
Ed Huntress
I'd tell you to check your hands to see if it is right, but that's probably a less than reliable reference. :o)
Tim
-- "California is the breakfast state: fruits, nuts and flakes." Website:
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Reply to
Tim Williams
I woud like to ask a question.
Why would anyone want to harden lawnmower blades? They are meant to cut very soft material (grass) by hitting it at high speed and splitting the stems. Hardnedd of the blade is irrelevant to grass cutting performance.
Hardening would not help much wrt dulling of blades when they hit rocks and soil at high speed. Rocks will be harder than the blade anyway and wil dull it regardless of hardening.
i
Reply to
Ignoramus31693
Well, it would tell me if I'd lost the same number off of each. I always thought those people who were born with six toes on one foot or six fingers on one hand had an unfair advantage.
-- Ed Huntress
Reply to
Ed Huntress
That's true to a point, but a sharp blade will leave a much cleaner cut (I sharpen mine all the time, and I have really clean-cut crabgrass and dandelions). A cleaner cut, if you have grass, leaves your grass less vulnerable to disease and drought.
The trick is to keep the rocks out of your lawn. I fight a losing battle in that regard, as the rocks here seem to breed.
-- Ed Huntress
Reply to
Ed Huntress
The primary reason is to reduce wear from sand. Sand is almost always lifted from most soils during mowing, and drastically reduces the life of the blades -- especially the "lift wings".
LLoyd
Reply to
Lloyd E. Sponenburgh
Not in my yard...wish I _had_ some sand.
Dave "Anyone wants to make bricks, call me." Hinz
Reply to
Dave Hinz

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