I've been using a grinding wheel and hand files to sharpen my mower blades. Thanks to advice here, I'm now using a flap wheel on an angle grinder. I'm just getting up to speed using this method, I can remove a lot of material pretty fast.

When is enough enough? How to know when I don't want to take any more material off? Not just from creating a dangerously thin blade but I'd think the momentum and counter balance of a too light blade would be a problem.

I've got 4 sets of blades to sharpen and have been thinking about these. What grit are you using?

Back when I worked commercially, we would sharpen blades twice a week and they would last most of the summer, as long as you weren't taking too much off each time.
Near the end of its life the blade would start to warp, noticeable by laying it on a flat surface.

Back when I was running a large commercial grounds crew, I would do a lot of sharpening, on a bench grinder mostly. One thing that many people don't realize is that it is the first 1/2" of the blade that does all the grass cutting, so there isn't any need to sharpen more down the blade than that, except to maintain blade profile. However, I didn't see much difference in cut quality with a steep angle on the cutting edge, even up to 45 degrees, it certainly doesn't have to stay square. The other thing, mower blades do not have to be all that sharp, "too sharp" looks pretty, but invites early damage and edge rollover.

I had to look up what a flap wheel was. I have always just used a dremel with a cone shaped grinder bit. What is the advantage of using a flap wheel?

I've never used anything but a side grinder

I use a bench grinder. I can't imagine doing it handheld? you need to balance them when you are done. Too thin isn't really possible since you aren't changing the thickness unless I misunderstand you.

hand held is a piece of cake. Use the flap disc 200-300 grit in an angle grinder because it's so much faster than a dremel and it's better. Same principle as the worksharp belt sharpener. stop when it's sharp, hang it on a nail to check balance. Replace the blade when the corners get rounded off.

I've never sharpened my mower blades. What is the advantage? Mine has always cut the grass satisfactorily.

Dull blades will tear the grass rather than cutting. Here's a good read.

http://www.omahaorganicslawnca...p-lawn-mower-blades/

I use a pistol grip air sander with the 2" screw on discs. If the blade is dinged I hit it with 40grit then I step it up. Really easy to get the blades balanced, gets right up against the center, and very easy to handle with the pistol grip.

I guess I will give the flap wheel a try. I only sharpen my mower blade every Spring when I also do an oil change.

I need to sharpen the blades on my Hustler 54" mower. I've learned something new (yet again) on this forum.

Hey doublesharp, do you also use that spatula on the grill?

quote:

Originally posted by architect:
..the first 1/2" of the blade that does all the grass cutting, so there isn't any need to sharpen more down the blade than that, except to maintain blade profile. However, I didn't see much difference in cut quality with a steep angle on the cutting edge, even up to 45 degrees, it certainly doesn't have to stay square.

Make sense on the first 1/2", I hadn't thought about it and have been sharpening too far down.
So then the 45 degrees would be preferred, no? Not sure what you mean "doesn't have to stay square".

quote:

Originally posted by hrcjon:
Too thin isn't really possible since you aren't changing the thickness unless I misunderstand you.

Sharpening down too far too many times would eventually thin down the the width, not thickness. I would guess the steel will get softer in time as material is removed and not hold an edge at all

This...



is not a flap disc. Flap discs have flaps. Lots and lots of flaps.

quote:

Originally posted by RogB:
Dull blades will tear the grass rather than cutting. Here's a good read.

http://www.omahaorganicslawnca...p-lawn-mower-blades/

Yup. Pretty easy to spot patches of grass where it’s torn instead of cut.

I just replace my blades every few years. Mine are extr3mly cheap.

I use one of these: http://www.rbggrinders.com/712.html

I bought a couple of blades for Dad's mower the other day at Lowes and it cost me $46. The old ones were beyond sharpening anymore, but I bet I sharpened them twice a year for better than 10 years.

Glad this thread came along. Thanks OP. I have been sharpening my blades for a few seasons on my bench grinder, but receintly my lawn has been cutting like crap. Lots of high spots that are seemingly missed although Im walking right over them. Almost as if the blades dont lift the grass enough before cutting. Im going to have them sharpened professionally just to see if its me or not, then move onto another pair of blades. Toro Timemaster btw.

"Not sure what you mean "doesn't have to stay square"."

The cutting edge and end of the blade doesn't have to stay square.

Be careful when sharpening that you don't remove material too quickly such that you put too much heat in the blade and screw up the heat treat.