mower blade sharpening?

[Errtt]

As mentioned - when I do my oil change (once a year), that's when I pull the blade and sharpen it.
I start out cleaning the muck with a wire wheel till it looks like its back to metal.
If its boogered up, I'll start off setting up a edge with a grinder. Finish off with hand files - checking & balancing it too.
Clean the hub & bolt, spread a very thin coat of anti-seize on the bolt then button her up.

Come spring - may or may not go with the same oil I been using since last spring. I'm using Amsoil 20-50 because it was left over from last spring motorcycle oil changes.
Previous oils were Rotella 5w-40 synthetic, and Rotella 15w-40 prior to that.

Honda HRX - not the standard blades I'm used to with other I had.

 

[Pop_Rivit]

I sharpen and balance the blades on my John Deere 757 once a week during mowing season. I often mow twice a week at just over an hour each time I mow. On occasion I help out a neighbor, so it's not uncommon for the mower to see 3-5 hours of mow time a week.

I keep two sets of blades-one on the mower and one sharp and ready to go. At some point in the week I switch them out and then sharpen and balance the set that's off at my leisure. When I put a set of blades on I also make sure everything is at the right height with a height gauge.

I run them up and down on the bench grinder to clean up the edge and then put them in a vice and finish with a hand file. They are very rarely off balance, but if they are I can remove a slight amount of material with the file to balance them. The blades spin at around 15,000 RPM, and I imagine it would get pretty harsh if the blades weren’t balanced. The blades aren't razor sharp, but I sure wouldn't want to grab the sharp edge without my leather gloves on my hands.

It takes all of about 10 minutes to do all 3 blades, and about 10 minutes to put the 757 up in the air and swap out the blades. By keeping the blades sharp I can run at full speed when I mow, and no matter how tall the grass is I always get a perfect cut.

 

[mva]

Originally Posted By: JHZR2
Also, when I've flipped my mower up/over, it is always harder to start, and it smokes bad for a while when I start it. Is this because the carb empties or because oil gets in somehow? How is this prevented?


Flip it with the carb side up and this will not happen.

Also, disconnect the spark plug wire before working on the blade.

 

[andyd]

Thanks for giving me something to do this winter you guys, I've got 3 mowers that need sharpening. I'm sure they will have a few dings. I just get them shiny on a bench grinder. Unless, I feel a vibration, I dont mess with balancing. But I'm a hack

 

[Ken2]

Oregon Gator blades work especially well for me in wet grass. I like them.

You don't want a hard blade. Hard steels are usually brittle. You want the blade to deform when it hits a rock or nail or something, not to break a chunk off and fling it toward someone.

 

[abycat]

Originally Posted By: JHZR2
Originally Posted By: abycat
I have used a good file on all of mine and have not balanced them since I dont take them off when i sharpen them. I do it once a year and they seem to cut grass just fine. If you look at the tops of the grass after mowing and they are all frayed then you need to sharpen the blade.


So that said, what's the benefit to balancing? What's the issue if one doesn't do it?


I think you have to take a heck of a lot of metal off for it to be not balanced. And my mowers have all been junk yard specials that I have got going again. I put a rock on the handle so the mower is doing a 45 degree wheelie and go from there. Just think all that smoke is some good upper cyl lube! JK.

 

[Bror Jace]

I have an assortment of grinders, Dremels and the like ... but use only a flat file and a vice to sharpen blades. It does a great job and removes the least amount of steel for longest blade life.

When I took care of dad's yard I would sharpen mower blades about twice per season. His soil was very sandy and the sand blowing around (as well as the occasional high spot) would really wreak havoc with the blades. They could have been sharpened every 3-4 mowings and blades would typically wear out after 7-8 years of regular mowing.

Also, as others have said you really don't want the blade razor sharp as it will chip more dramatically if/when you hit a stone or piece of metal. Be sure to preserve the factory angle to the cutting edge (easy to do with a flat file).

You can mow grass with a very dull blade ... but it is hard on the grass. Rather than a nice, clean cut, the dull blades thrashes the top the grass pulling on it as it cuts. Can you tell the difference after it is cut? Probably not, but if you have a problem yard and/or want to do the best for your lawn, use a (reasonably) sharp blade.

I have used the cone-type balancers as well as a nail in a door or wall. I have never ruined a mower by using an unbalanced blade.

 

[Woody71]

I use a 10" [censored] cut mill file in a bench vise. I don't always sharpen during an oil change. I make sure there's little or no gas in the tank and flip the mower so the carb is facing up. I balance the blade after sharpening and file down the heavy side until it's balanced. I tighten the blade back on with a socket wrench and then a torque wrench set to manufacturer's specs.

 

[Bror Jace]

As for not leaving the blade too sharp, this diagram shows what we mean:

http://i229.photobucket.com/albums/ee149/BrorJace/MowerBlades.gif

Basically, I sharpen the blade very well then go over the edge at a 90 degree angle very lightly to take that razor edge off of it. No more than that.

 

[boraticus]

Ahhh, yeah.....

We're cutting grass here, not open heart surgery.

Put a reasonable edge on the blade and go cut some grass. Cut for one minute and take a look a the blade. That sharp edge will be blunted.

I'm not too worried about the exact angle either. I try to keep it fairly close to original but don't lose sleep if it's off a bit. Grass doesn't seem to know the difference.

I don't use a torque wrench either. The bolt that holds the blade on is plenty long, fine thread and strong. I just crank it down and go to work. Never had a blade loosen in over thirty years.

Put a torque wrench on it if you want, but it's really not necessary.