Sharpening Mower Blades?

[Matt Meiser]

How do you do it? I need to get better about doing it. It seems like the bench grinder works the worst for me--overheating, uneven, etc. Using a flap disc on an angle grinder seems to work OK. It seems like a belt grinder would work best if I could find a decent 1" wide machine but most are way underpowered.

How do the pros do it?

Edit: I'm talking about the very heavy 21" blades my ZTR uses. Very much like the ones my 60" belly mower used to use.

[David Weaver]

The pros often have a jigged machine to do it, with a front bevel and a back bevel set (i guess some do the back bevel by hand). Youtube it, and you can see people trying to sell the machines.

I do my 21" blades by hand on the bench grinder (in a pedestal with plenty of room around it) and then finish the edge off with a file and file on a back bevel for edge strength.

It's important to have a balancer, either make one or buy one for about $5 or whatever they cost.

If I were using an angle grinder, i'd use a flat disc instead of a flap disc.

( a kalamazoo 1x42" grinder do them fine, too, as long as it had a fairly coarse belt on it).

[Ben Hatcher]

I actually use my worksharp to sharpen my mower blades. It works great.

[Bryan Slimp]

I use a Dremel with a sharpening/grinding stone (both the bevel and flattening the immediate back of the edge) and then go over each side with varying grades of the small sand paper tubes (course to fine of course.) I kind of thought about it like sharpening and then honing plane irons.

[Charles Wiggins]

http://www.lowes.com/pd_96691-273-06601L_4294936478__?catalogId=10051&productId=3108231

[Bob Rufener]

I use my belt sander. I have a belt I use exclusively for sharpening my mower blades. I put it in a vice and have at it. Easier to hold the correct angle this way. It is also easy to check balance. Drive a large nail into a wall and put the blade on it. Hold it horizontal to the ground. If it stays put, it is in balance.

[Myk Rian]

I use a drum sander chucked up in the drill press. It doesn't burn the blades, and gets them sharp.
Works great to get the flat on the back of the blade.

[Jerrimy Snook]

As easy as it looks to get to the blades on that mower, I'd hit them with a file every few mowings. You'd only need the grinder if you were mowing rocks and foreign objects. The method matters less than the balance. It would be difficult to affect the balance with the file. We use one of these (http://www.magna-matic-direct.com/MAG-1000-Blade-Balancer-p/mag-1000.htm) to check balance but a steel rod or screw driver should be accurate enough.

[Greg Portland]

Check with your manufacturer. My Honda push mower service manual recommends that I only sharpen a single bevel (versus both sides) and then they recommend that I break the edge with a file (i.e. no longer super sharp). Supposedly this helps prevent the blade from chipping when you hit a hard root or rock. I check the balance with a thin screwdriver.

[Matt Meiser]

There does end up being a lot of foreign material in my yard--sticks, stones, etc. And we've got very sandy soil which just sandblasts the blades. So I think even with frequent sharpenings I'm still really looking at more of a grinding option.

I looked up some commercial grinders. I could fabricate something like those real easy...

[ray hampton]

I hit the blades lightly with a hand grinder without removing the blades the last time

[David Weaver]

If you have a bench grinder that has free lateral access (like the motor is behind the wheel diameter laterally), you could easily make a fixture to lay the blade in on a bench grinder and pull it through.

[Brian Elfert]

I have always used a bench grinder to sharpen my mower blades without issues. I did have to replace the blades once because the sand in my yard wore off the back lifting edge. I cut grass at a large public facility once where they had 15 or 20 mowers. The mechanic there had to sharpen a half dozen or more blades a day. He just used a regular bench grinder.

[Ben Hatcher]

There does end up being a lot of foreign material in my yard--sticks, stones, etc. And we've got very sandy soil which just sandblasts the blades. So I think even with frequent sharpenings I'm still really looking at more of a grinding option.

I looked up some commercial grinders. I could fabricate something like those real easy...
You certainly could build one. My grandfather made a custom blade grinder about 50 years ago. It works perfectly to this day. The blade rest is a piece of wood cut to the give the right grind angle laminated with a sheet of brass. If I had to guess, it is probably turning at ~900 rpm with a 1750 rpm motor and about a 2:1 pulley ratios.

[Lee Schierer]

I use a large mill file with the blade clamped in a vise. I only sharpen a single bevel as that is the way the blades came from the factory.

[Bill Huber]

I use the kinfe sharpener from Worksharp and then check the balance with a fishing line.

[Jim Matthews]

+1 on the mill file in a vise.

I have higher clearance over sandy ground, so the blades last a little longer.
I have substituted a string trimmer for steeper pitches on the lawn - less gas consumed.

I use a walk-behind Lesco and it prefers going straight down hill to sideways along the berm.

[Matt Meiser]

I did some more reading over on the lawn site forum for landscape pros. Seems there's a pretty good mix of bench grinders, dedicated blade grinders, and angle grinders in use by the pros. A dedicated machine isn't in the inexpensive category but looks to me to be nearly foolproof. I still think I might try to build a clone of the Oregon/RBG grinders if I can find a suitable motor at a nice price. But one of those Kalamazoo 1x42 machines would find a lot of use in my shop too.

[David Weaver]

When enco has sales, it costs about $215 or so to get one of those kalamazoo grinders delivered. I've had both the viel tool grinder that LV sells (and if you're budget conscious, you use an AO smith motor with it, or a used similar motor), and the kalamazoo grinder. The rest of the viel grinder is more substantial, but I like the rest of the kalamazoo a lot better - it tracks *much* better and the belt speed is a little slower and better for sharpening things in general, especially if you apply pressure against the platen.

[Ole Anderson]

Thanks guys, now I have to go out and sharpen my blades, I usually don't give it much thought until someone reminds me. I use a bench grinder with a coarse stone on my 48" Z425 (Deere zero turn) blades.

[Phil Thien]

Well all I can say is that lawn guys aren't anything like woodworkers, or else they'd all upgrade to some some sort of replacement blade with carbide inserts, and they wouldn't dare mow the lawn without some sort of dust collection.

[Brian Ashton]

I use a standard grinder disk on an angle grinder. I don't think the average mower has high enough rpms to be affected by a minor imbalance from hand sharpening.

[Joe Kieve]

Sharpen...you mean you're supposed to sharpen a lawnmower blade? I figure Sears knew what they were doing when when they put 'em on the mower! Seriously, ocassionaly I touch mine up with an air powered die grinder.

Joe

[Dave Lehnert]

When will Lee Valley come out with a set of A2 steel blades :)

[Matt Meiser]

That would make the mower look cheap!

[Harry Hagan]

I use my Ryobi belt sander. The wide bottom plate affords more control in maintaining a straight edge and holding the sander at the correct angle. The variable speed helps keep the heat down. It works great on shovels too. It’s MUCH better than using an angle grinder.


231930

[Scott T Smith]

Matt, here on the farm sharpening mower and bushhog blades is a frequent occurance in the summer - if not weekly then bi-monthly. Over the years I've tried a lot of different options for sharpening blades.

The fastest and easiest way that I have found is to raise my Scag up on an auto lift, and use a 4-1/2" Makita angle grinder with a flap sandpaper disc (flat) on it to sharpen them in place. I typically use either a 60 or 80 grit disc. The nice thing about this setup is that the flap disc does not heat the blade to the point where it will lose the temper on it's edge (which a regular grinding disk will).

The flap disc that I use is similar to this one: http://www.amazon.com/SAIT-79118-Encore-Type-Flap/dp/B004TN7VYC/ref=sr_1_15?s=hi&ie=UTF8&qid=1336849053&sr=1-15

Option number to is to do the same thing, except remove the blades from the mower and clamp them in a bench vise.

[ray hampton]

Scott , about sharping the bush hog, can you tilt the bush-hog up on its side or on the end while it are still mounted to the tractor, this would be the quick way to sharper the blades

[Myk Rian]

My brother used his mower for 3 years before he decided to get the blade sharpened. When he was taking it off, he discovered it was on upside-down. He had been mowing the lawn with the back of the blade. He got a free sharpening just by mounting it correctly.

[Scott T Smith]

Scott , about sharping the bush hog, can you tilt the bush-hog up on its side or on the end while it are still mounted to the tractor, this would be the quick way to sharper the blades


Ray, I've lifted the back of them up before, but I don't like rolling underneath it w/o some type of safety. Plus, when I'm underneath it with an impact all of the crud drops down in my eyes.

Instead what I do is to remove the top link, and then use a forklift to raise the back end of the bush hog almost vertical. This makes it very easy to access the blades for removal.

Because of the way that they pivot, it's a bit of a pain to sharpen them on the unit (they don't stay still), so these are usually removed and sharpened on the bench.

[ray hampton]

that is about what I remember, I was thinking about the highway mowing machines, when they finish mowing the bush-hog are raise to close between 70-90 degrees, almost vertical, I tend to forget about the ferment grass

[Matt Meiser]

I suppose I should sharpen my brush hog blades too.

[ray hampton]

I remove mower blades before that I would use a wood block to block the blade so the nut could be remove and replace, the same upset [ that are suppose to say setup ]will hold the blade for a sharping

[ray hampton]

which name are correct "bush-hog or brush-hog ?

[Matt Meiser]

Technically rotary cutter. Brush or bush? Hog is a brand name.

[Ron Jones near Indy]

I put the blades in the vise and hit them with the angle grinder.

[Tim Morton]

I just replace them every 3 or 4 years whether they need it or not...:o

Kind of timely here, since i just pulled mine off yesterday for replacement....but i think this will motivate me to at aleast attempt to go the srarpening routge next time.

[Jim Becker]

I sharpen mine with an angle grinder...I lift the ZTR up with the tractor FEL so I can put the front of it on jack stands, and then lie on the ground and do the blades with the angle grinder, only working on the blade section closest to the front so that I never have much of my arm under the unit. Which reminds me...I need to do this real soon now!

[Pat Barry]

This doesn't have to be anything fancy. Use whatever is the easiest. I use the bench grinder because I don't like to waste my time with a file. I balance the blade on my finger tip. When the blade gets too skinny I replace it. Belt sander - sure, but if you have the bench grinder why bother. Just take light passes, eyeball the bevel and put your efforts into something productive. Now, if you are in the running for most beautiful yard, the cover of Home and Gardens, or working at Augusta National then by all means get sophisticated. You don't want those ugly split ends in any of those situations.

[BOB OLINGER]

I put mine in the vise and use the angle grinder - very fast. Likely best to avoid razor sharp edges as they are more prone to chipping - not saying I fully abide.

[David G Baker]

Due to the large amount of sand and rocks on my property I have to replace my blades almost every year at around $40 for each change. By the time I change them there isn't much metal left to sharpen.

[Jerome Stanek]

Due to the large amount of sand and rocks on my property I have to replace my blades almost every year at around $40 for each change. By the time I change them there isn't much metal left to sharpen.



I think you are doing something wrong. Your supposed to mow grass not rocks.

[David G Baker]

Jerome S.
The rocks that get mowed are rocks from a neighbors driveway that are pushed on to my property during the Winter by a snow plow. The rocks are hidden from view by grass and most are on a steep bank that is risky. If there was an easy way to remove the rocks without investing in some expensive equipment I would explore it. My snow removal also moves rocks into my lawn area. I rake the areas but I frequently miss a few. My lawn is around 3 acres, what I should do is let the grass grow and cut it with my brush hog couple times a year. The brush hog has much better clearance than the riding mower. Sand probably does more damage than the rocks.

[Roy Turbett]

I use my belt sander. I have a belt I use exclusively for sharpening my mower blades. I put it in a vice and have at it. Easier to hold the correct angle this way. It is also easy to check balance. Drive a large nail into a wall and put the blade on it. Hold it horizontal to the ground. If it stays put, it is in balance.

+1 on the belt sander and nail.

[Leigh Betsch]

Japanese water stones. Start with 1000g, move up to 32,000g. Ruler trick if the rock chips are too deep!

[lowell holmes]

+2 for mill file in a vise. I have a good coarse mill file.

[Gary Hodgin]

I've used a low-speed bench grinder, angle grinder, dremel, files, and recently got a Work Sharp Knife and Tool sharpener as a gift. IMO, the Work Sharp is the easiest and fastest. It doesn't require hardly anything with respect to setup, easy to maintain original bevel, and easy to maintain blade balance. I plan to use it for all my knifes and yard/garden tools. I got mine at Northern Tool for $69.

[Jason Roehl]

I use a bench grinder, but I hold the blade against it when I turn it on and keep just enough pressure on it to prevent the grinder from coming up to speed so it doesn't burn the blade.

[Keith Outten]

Be Safe!

No matter what method you use to sharpen your mower blades make sure you clean them first so you can inspect the blades for damage. Pay particular attention to the area around the bolt hole and look closely for cracks. Use a wire brush to get the blade as clean as possible so you can see anything that looks suspicious and dispose of blades that you suspect are defective.

Don't ask me why I am so serious about inspecting blades, my story involves an accident my Mother had with a mower when I was young and it is a gruesome tale.
The same thing applies to sharpening planner and joiner blades, they will develop transverse cracks at any point along the blade.
.

[Brian Elfert]

Where I cut grass for a few summers we had a old tractor with a belly mower. It had thin spindles and they would periodically snap off ejecting the blade and spindle. Luckily, nobody ever got hurt. It was used for mowing fields used for parking when the lots were empty. I noticed they bought a new John Deere tractor with a three point mount mowing deck about 10 years ago.

Interesting story about the old tractor. It was a McCormick-Farmall from the 50s I think. We noticed one summer the oil pressure gauge was reading zero. We thought the gauge was broken. This went on for weeks and finally someone checked the oil. It was really low on oil and when it was filled up the gauge started showing oil pressure. The engine never showed any ill effects. The operator was lucky not to be fired as the oil was supposed to be checked every time gas was put in which was once a day at least. That tractor just ran and ran. The clutch finally had to be replaced around 1992 and nobody could any records of ever replacing the clutch since new!

[Kevin Bourque]

I live on a farm in Pa. and am responsible for cutting the grass. It takes between 7-8 hours a week on average . We have lots of rocks, branches, and a big gravel driveway that eats up the blades pretty fast, so I started sharpening the blades with a belt sander about 5 years ago and haven't touched a grinder since. Th sander works just fine and it goes quickly once you get the hang of it.

[ray hampton]

I live on a farm in Pa. and am responsible for cutting the grass. It takes between 7-8 hours a week on average . We have lots of rocks, branches, and a big gravel driveway that eats up the blades pretty fast, so I started sharpening the blades with a belt sander about 5 years ago and haven't touched a grinder since. Th sander works just fine and it goes quickly once you get the hang of it.

what do you do when it rains every day or every other day ? can you mow in a rain storm ?

[Kevin Bourque]

what do you do when it rains every day or every other day ? can you mow in a rain storm ?


I always wait until the grass is dry, otherwise the clippings just clump up and clog the mower( John Deere 4115)

[ray hampton]

I always wait until the grass is dry, otherwise the clippings just clump up and clog the mower( John Deere 4115)

I saw landscaping crews mowing the grass in a light shower but they got so many jobs to get cut per day

[Matt Meiser]

Well, I really like that 1x42 Kalamazoo sander for my shop, but its not the best for mower blade sharpening. Its hard to get the blade into where the platen is located and where the belt is more open without the platen the belt tends to round things over. It did work really well on my wood chipper's knives. So now I'm back to debating between a dedicated purpose-built blade grinder and using the angle grinder which I've not been very good at in the past. At $60 a pop for blades shortening their life isn't cheap. I found I could get them sharpened locally for $18-30 depending on the place. I wasn't super thrilled with the $18 place which is just around the corner. Doesn't take too many sharpenings at $30 to pay for a decent grinder.

I ended up buying a MoJack lift for the mower in the fall. at least the one I have there's just no safe way to jack up the front without lifting the whole machine by the deck which is not good, and even then I couldn't get it high enough to get the impact gun on the spindle bolts. The MoJack is much safer and quicker and takes very little storage room because I can park the mower right on it.

Also regarding mowing wet...I did it (morning dew, didn't rain much last year :() just to see if I could and the design of the deck on this thing results in it staying amazingly clean. I didn't even bother scraping off the little there was.

[Ole Anderson]

Earlier I said I sharpen mine with a coarse wheel on a grinder. Last time I tried a 80 grit on my 1 hp 6x48 belt sander, worked MUCH better. Sure helps having an impact gun to remove the bolts on the blades. Lift the front of my 48" 425ZTR with a come-along and then support it with jack stands to access the blades.

[Tom Fischer]

Hi Matt,

I once had my older Lastec 521 sharpened at the dealer. Looked like the blades were on a belt sander, perfectly flat.
I swapped that out three years ago for a slightly used 3696 (http://www.lastec.com/lastec2/Products/ZeroTurnMowers/369696Cut.aspx).
I just put the blades on grinder, small bucket of water nearby to keep them cool.

But all rotary mowers are "rough" mowers. No matter what you do with the blades, the grass edges will be slightly torn when cut. And the tear turns into a slight brown edge.
OK for my yard, but not OK for 300 acres of expensive golf course fairways and greens.
For the fine cut, golf courses stick with "scissor cut" reel mowers, and I think that's 9 blades per reel. I had a very old 5 blade reel mower (a three gang Worthington rough mower) many years ago.
Had to send it out to sharpen it. Not worth it. Gave it to a friend who likes Worthingtons.

[Brian Ashton]

I leave the blade in the mower and hit it with an angle grinder and regular grinding wheel, then a quick touch with a file to get a bit of a back bevel. It may not make for a perfectly razor sharp blade but all I'm cutting is grass... So by comparison to a weed eater line it's much better and they do a pretty good job so... Balance hasn't been an issue either I just measure every once in a while the width and length of ground area and make sure they're close. After all it's a lawn mower and perfect balance isn't expected or necessary. It's worked for 30 years so far but ymmv