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

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
...
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

Haaken Hveem wrote:
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.



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

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"As long as there are final exams, there will be prayer in public
schools"

"Gene Kearns" wrote in message
...
On Wed, 13 Apr 2005 23:08:04 +0100, "Haaken Hveem"
wrote:

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!


Not likely enough carbon to harden.....

The easy way of hardenig is to heat the blade dull red. and throw it in a
can of water.


I have never seen a hardened blade. Hardening makes them more brittle.
Brittle makes them break. Breaking turns them into shrapnel. Shrapnel
is bad......

And usually addressed "to whom it may concern"!

"EW" wrote in
:

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



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!


--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

Remove sp to reply via email

"EW" wrote in message
...
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.

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 G.

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

Mower blades are not hardened to anything appreciable. To do so would

I regularly sharpen my blades with a file. They are not hard at all.

chuck

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:
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

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.

--
Steve W.

"Jeff Wisnia" wrote in message
...
Haaken Hveem wrote:
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.



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

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"As long as there are final exams, there will be prayer in public
schools"



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"Anthony" wrote in message
...
"EW" wrote in
:

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



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!

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

"Lloyd E. Sponenburgh" wrote in message
ink.net...

"EW" wrote in message
...
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.

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 G.

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.

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

"Ed Huntress" wrote in message
...
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.

Yeah... and I'm SURE that flesh understands and reacts positively to the
difference between 3000 RPM 'soft' blades, and hardened ones! G

Doesn't the CPSC do the dumbest things?

LLoyd

"Lloyd E. Sponenburgh" wrote in message
ink.net...

"Ed Huntress" wrote in message
...
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.

Yeah... and I'm SURE that flesh understands and reacts positively to the
difference between 3000 RPM 'soft' blades, and hardened ones! G

Doesn't the CPSC do the dumbest things?

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. g

--
Ed Huntress

"Ed Huntress" wrote in message
...
That's the right number,
I think. g

I'd tell you to check your hands to see if it is right, but that's probably
a less than reliable reference. )

Tim

--
"California is the breakfast state: fruits, nuts and flakes."
Website: http://webpages.charter.net/dawill/tmoranwms

"Tim Williams" wrote in message
...
"Ed Huntress" wrote in message
...
That's the right number,
I think. g

I'd tell you to check your hands to see if it is right, but that's
probably
a less than reliable reference. )

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

"Ignoramus31693" wrote in message
...
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.

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.


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.

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

"Ignoramus31693" wrote in message
...
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.

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

On Fri, 15 Apr 2005 19:18:53 GMT, Lloyd E. Sponenburgh wrote:

"Ignoramus31693" wrote in message
...
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.

The primary reason is to reduce wear from sand. Sand is almost always
lifted from most soils during mowing,

Not in my yard...wish I _had_ some sand.

Dave "Anyone wants to make bricks, call me." Hinz

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.

But the blades still dull and need to be sharpened.
If the edge was harder, they would not dull as fast.
I have a relatively small yard, and I still need to
sharpen blades every 3-4 cuttings.

cs

On 15 Apr 2005 20:41:18 GMT, Chuck Sherwood wrote:
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.

But the blades still dull and need to be sharpened.
If the edge was harder, they would not dull as fast.
I have a relatively small yard, and I still need to
sharpen blades every 3-4 cuttings.

Are you hitting stones or dirt a lot? That seems very excessive.
Problem with hardening the blades, is that they'd then be brittle.
So, instead of rounding off, they'd fragment. Either way, not what
you want. I think it's a better approach to figure out why you only
get 3-4 cuttings out of a set of blades; mine usually go a season,
mowing about 4-5 acres with a 3-blade deck.

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.

But the blades still dull and need to be sharpened.
If the edge was harder, they would not dull as fast.
I have a relatively small yard, and I still need to
sharpen blades every 3-4 cuttings.

cs
If you are serious about "fixing" the wear problem, I would look into
a rod that Lincoln (and probably others, too) have on the market,
which I believe is called "Abrasoweld" or something in that order.
It's used to "build up" plowshares, etc., that have contact with the
earth. It resists wear from the dirt. You could lay a bead of that
on each cutting edge, then sharpen and it probably would last a while
longer. HTH
Ken.

If you want to hardface your blade this is the place to lay the bead. It
will make them self sharpening.
/----------------------------------------------------------
/-----------------------------------------------------------
*
Steve



Ken Sterling (Ken Sterling) wrote in message
...
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.

But the blades still dull and need to be sharpened.
If the edge was harder, they would not dull as fast.
I have a relatively small yard, and I still need to
sharpen blades every 3-4 cuttings.

cs
If you are serious about "fixing" the wear problem, I would look into
a rod that Lincoln (and probably others, too) have on the market,
which I believe is called "Abrasoweld" or something in that order.
It's used to "build up" plowshares, etc., that have contact with the
earth. It resists wear from the dirt. You could lay a bead of that
on each cutting edge, then sharpen and it probably would last a while
longer. HTH
Ken.

Are you hitting stones or dirt a lot? That seems very excessive.

No. I have a relatively small yard. My entire lot is 7k sq feet and
subtract off the house and driveway, I'm probably only mowing 4k
square feet. I can cut it in 30-40 minutes with a toro self propelled
walk behind mower. My blades are soft steel and I sharpen them with a file.
I need to keep the blades fairly sharp becuase this mower is only 3.5HP
and I can tell a big difference with sharp blades on a dense lawn.

On 15 Apr 2005 20:52:18 GMT, Dave Hinz wrote:

On 15 Apr 2005 20:41:18 GMT, Chuck Sherwood wrote:
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.

But the blades still dull and need to be sharpened.
If the edge was harder, they would not dull as fast.
I have a relatively small yard, and I still need to
sharpen blades every 3-4 cuttings.

Are you hitting stones or dirt a lot? That seems very excessive.
Problem with hardening the blades, is that they'd then be brittle.
So, instead of rounding off, they'd fragment. Either way, not what
you want. I think it's a better approach to figure out why you only
get 3-4 cuttings out of a set of blades; mine usually go a season,
mowing about 4-5 acres with a 3-blade deck.
My $2 mower gets sharpened every spring (yesterday) when I pull it out
from under the canoe and change the oil. This year I even cleaned the
points and spark plug because it wasn't starting on the second pull
last fall. I gave the lady $2 for it seven years ago and installed a
new carb diaphragm and pop riveted several bits of sheet steel (old
computer cases) on to reinforce the shroud since then - some day I may
even paint it.
Gerry :-)}
London, Canada