Let's talk lawn mower blades!

[Rodvan]

I'm tired of sharpening the blades every time I mow the lawn! I replaced the blades on my 2004 Husqvarna lawn tractor with "commercial quality" blades, but after mowing about one acre they're dull... I tried replacement blades from the dealer but nothing lasts more than a couple of cuttings. A friend that has a John Deere said he only sharpens the blades once a year. He also said other higher end mowers have blades made from a different type of steel. He didn't know what type of steel to look for but thought I could get something for my Husqvarna. So, does anyone know what type of blade will last all season or half a season before it needs sharpening? I'm in Michigan so we're talking six months at the most.

[Garyshome]

Head on down to your local welder and have him braze on some Carbide on your blade. you should be good to go for a while.

[Der Gebirgsjager]

I've got a Sears Craftsman 2003 rider mower which was made by Husqvarna, just red instead of orange. I'm thinking that you must mow much more than the half-acre I mow, because my last factory blades lasted for 3 years, and there isn't anything special about them. The mower guy was just here to get me going for this season. Oil change, lube, new blades, air cleaner service $307--but that also included ordering a new top belt to have on hand just in case, which ran $59. Two of the three old blades could be saved for hard times, so I put them in the shed.

[Plate plinker]

don't know about your mower but my three point finish cut mower has hardened steel cutting surfaces they last over a year with little wear while cutting 2.25 acres. look for something like that.

[aspangler]

Sharpen then heat with a torch until the cutting edge turns blue. Quench in COLD water. They will last a LOT longer unless you hit a lot of rocks etc.

[roysha]

Having been in the business for quite a number of years, I believe I can safely say that there is no practical difference in the material used in mower blades among the various brands.

My first thought is that you are using "recycler" blades and if you are mowing something other than urban lawn, which is usually quite clean, versus weeds, dirt, gravel and heaven knows what all else that is usual with rural mowing, your blade life will be substantially shorter since you are, in effect, cutting the same "stuff" multiple times. If that is the case, I would suggest a heavy duty high lift blade to blow the clippings clear.

In regard to the "hard facing" suggested in one of the responses I will say I tried something similar using stellite and it was an unmitigated disaster!!! The stellite was so hard it was extremely difficult to sharpen and chipped and broke at the thin cutting edge. Where it had substantial base metal it held up well but I might as well have had the blades on upside down for having a sharp cutting edge. Once again it was "sticks and stone" that were the culprit, not the grass.

[Lead Fred]

Sears, Husky,MTD, and several others all use the craftsman style deck.

A deere deck is like a battle axe compared to the others. the triple deck and heavy blades are at the top of the heap.

and lets not weld blades, the harmonics can shatter two piece blades. Some deere blades might handle it, but Ive seen decks they fly right through.

[country gent]

We hard surfaced some with hard surface welding rods ment for the teeth on back hoe buckets. DOne acording to instructions with the rods it held up better but the inital balanceing and sharpening was a pain in the bottom. We welde D-s tool steel to some at work for cutting edges and it to held up as long as hard things like stones werent hit or picked up. Another killer of lawn mower blades is the ground your in sand that blows makes mowing almost the same as grinding the blades with it in the grass. Im in yellow sand here and my lifts on the blades go before the cut edge is worn out. I use high lift gator blades on my grasshopper and the lifts last about 3-4 years. The sand just cuts them to pieces. mowing over a gravel drive way even not picking up stones that cloud of dust is abrasive and working on the blades. CArbide would shatter the first time it hits anything hard, stones, edge of concrete, possible sticks and cans. Most hardened steel is also brittler and harder to work with.

[country gent]

We hard surfaced some with hard surface welding rods ment for the teeth on back hoe buckets. DOne acording to instructions with the rods it held up better but the inital balanceing and sharpening was a pain in the bottom. We welde D-2 tool steel to some at work for cutting edges and it to held up as long as hard things like stones werent hit or picked up. Another killer of lawn mower blades is the ground your in sand that blows makes mowing almost the same as grinding the blades with it in the grass. Im in yellow sand here and my lifts on the blades go before the cut edge is worn out. I use high lift gator blades on my grasshopper and the lifts last about 3-4 years. The sand just cuts them to pieces. mowing over a gravel drive way even not picking up stones that cloud of dust is abrasive and working on the blades. CArbide would shatter the first time it hits anything hard, stones, edge of concrete, possible sticks and cans. Most hardened steel is also brittler and harder to work with.

[Mk42gunner]

Oregon usually makes a blade to fit most lawnmowers. They seem to last pretty well; I put a set on a Woods belly mower and used it for five or six years, sharpening once a year at most.

From what I've read, you don't really want a sharp edge on a mower blade, supposedly if you leave a flat (about 1/16") on the very edge it holds up better, and cuts just as well.

Robert

[RogerDat]

I'm mowing over an acre and using sears regular blades they are "ok" for a year, using the sears higher quality blades they stay nice and sharp for a year. I do cut my grass long to shade the roots so I am not picking up as much ground grit, and not cutting through as heavy of grass. Not all blades of grass will be tall enough to get cut.

I did take more wear to the corner formed by the cutting edge and end of blade when I lived on sand. Too sharp an angle will wear fast, so you don't want a razor sharp blade but a dull blade will bang through the grass rather than slicing it, and dull faster for the beating.

This is an odd one but I saw it before so I'll mention it. Check to make sure the mower deck is clean and clear all the way around. I had one that would build up dirt and clippings in the middle of the back and at one corner. Blade edge was literally getting ground to nothing by going through those two chunks of adobe brick. Had to drive up on car ramps to really see it. Now I spray under deck with the hose every time and about once a month hit it with a small pressure washer while up on the ramps.

[country gent]

Grass hoper recomends sharpening lawn mower blates with a 1/32"- 1/16" flat instead of a knife edge and sharpening every 8-10 hours of use. I mow 2 aceres in 45 mins that 10 hours is about the summer. I dont sharpen untill after the first 2 mowings in the spring snow plows kick stones and roll sod up, nighbors snow blower throws stones untill they are gone its no point sharpening blades.I sharpen my blades with a 14" double cut file rough and the 12" fine single cut to finish edge and the 1/32 flat. I also make sure they are well balanced as this helps keep spindles in good shape.

[lefty o]

if your blades are hitting dirt, that'll dull em very fast. raise the deck a notch or two, dont scalp the lawn.

[Col4570]

The manufacturers are right in not hardening blades since hard usually means brittle.Better to sharpen frequently than to have the edge shatter or worse the whole Blade might sepparate.I thought about riveting hard edges to the blades of my rotary Mower at one time but decided against it since the attachments could turn out to be a missiles if they broke loose.

[Mytmousemalibu]

Always wondered if a quick doping of Kasinite or Cherry Red would do any good? Put some surface hardness into the blade surface but leaves a ductile core. I would second trying to leave a thin flat edge to the blade.

[StrawHat]

As a sharpener, I get to sharpen and balance more than a few lawn mower blades each week. A belt sander with 60-80 grit paper makes quick work of it, BUT, you have to work in short spurts to avoid heating the blade. The flat edge is a good idea but accomplishing it is not often as easy as it sounds, it needs to be at right angle to the plane of the blade. What has been said about cutting soil and rocks is absolutely correct, they destroy an edge quickly. Better to cut at the top of the grass and leave more of the blade to grow.

You want the blade of grass to look like it was cut with a pair of scissors, not torn and jagged.

Kevin

[oldred]

As a metal worker I see two suggestions here that I must disagree with, first NEVER weld or braze anything on a lawn mower blade! Those blades are carbon hardened steel and as such tend to form microscopic cracks at the edge of the weld, this can easily lead to the weld breaking off especially if something hard is encountered and the parts can come off with enough force to actually penetrate the deck! Also the suggestion to heat the blade to blue color and then quench puzzles me, why would you do that? Heating until blue and then quenching is the tempering step of the hardening process and makes the metal softer not harder! The right way to do that would be to heat until bright red then quench, only after doing that would heating back to blue and quenching again temper the metal to the right balance of hardness and ductility, of course the blade is already hardened and tempered from the factory so any heating of it is simply a bad idea.

[Hamish]

I strongly suspect the OP is sharpening at way too steep an angle. As has been mentioned, are you scalping the grass (dirt)?

Try these, ESPECIALLY in the fall with leaves: http://www.gatorblade.com

[oldred]

Always wondered if a quick doping of Kasinite or Cherry Red would do any good? Put some surface hardness into the blade surface but leaves a ductile core. I would second trying to leave a thin flat edge to the blade.

Likely it would do more harm than good because the blades are high carbon steel and already hardened all the way through, adding more hardening chemicals to the outer surface is very likely to create an extremely brittle blade. Hardening products such as Cherry red are meant for steels that can not be hardened by heating and quenching such as mild steels and softer alloy steels and is used to add a hard "skin" over a soft inner core, steels with a high carbon content are simply heated to the critical temperature then quenched causing the carbon to make the steel extremely hard all the way through. This is then followed by the tempering process which has already been described, heat to the tempering temperature (usually just until turning blue) then quench again to soften the metal back to a more ductile state. The finishing temper step leaves the metal somewhat softer than the first higher heating stage but still much harder than in the normal state and makes the part more ductile and much stronger.

[Hamish]

All this talk of welding and hardening blades scares the living snot out of me. Do you folks realise how many thousand RPM these chunks of steel are spinning at?

You grenade a blade and there's no telling what kind of death and destruction you're looking at.