Sharpening Mower Blades? EdgePro? Stropping?

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WadeF

WadeF

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So do any of you knife knuts sharpen your mower blades with your Edgepro? Do you finish them off with the 3000 grit polishing tape so you can see your own reflection? Or strop them until they pop hair off your arm at tree top level? :)

I just got a new John Deer walk behind mower and I was thinking how it would do if I put a scary sharp edge on the blade. What kind of edge are on mower blades? Probably chisel ground?

I should sharpening mine up, let my grass grow 2 feet high, and then drop the speed control to full speed ahead and see what happens. :)
 
Your EdgePro might not make a thick-enough angle for your mower blades. Were you psychotic enough to break out the premium sharpening tools on your mower blade, I wouldn't take the finish higher than the EdgePro's 600x stone. Can't see why you'd need more than a very thick chisel edge, but a very thick convex edge might be fun.
 
Yes they are chisel ground edges. No, you don't want a scary tree top sharp edge. That type of edge wouldn't last 1 cutting. What you want to do is grind in your angle what ever the factory angle is, then put a small 90 degree flat on the very edge. Only about 1/32 thick. The speed of the blade and the 90 degree edge is what will cut your grass, and this edge will last much longer than a edge ground all the way like a common chisel edge.
 
Don't sharpen your mower blades that sharp or the edge will last about one trip around the yard :( the angle they come is set perfect for them so the best thing to do is always resharpen at that angle. It's way to much trouble taking them off and sharpening them to do it in a way that you will have to every time you mow and dull blades just beat the grass down.
 
Just wanted to say I HATE LAWNMOWWER BLADES! My cousin started a lawn mowing business last year and asked me to sharpen his blades. How could I say no? I was sharpening 12 blades every week that required alot of grinding to get properly sharpened. At the end of last year he asked me to teach him how to sharpen them, thank goodness.
Wade I would stay with the factory bevel and not worry about sharpening them to scary sharp. They wear extremely fast, don't know what kind of steel they are. What do you think about a lawnmowwer blade with A2 inserts on the cutting edge? :eek:

Tom
 
Grass cutting blades tend to work best when highly sharp, as otherwise you get tears rather than cuts. The ones I use manually have the highest sharpness I can put on them.

For the powered ones, they also work better that way[*] - but you also have to factor in the contact with debris. If you have a very clean lawn it is one thing, but if you have kids, or a dog, etc., the blades will get blunt by contact with miscellaneous objects long before the grass would wear it down / roll it.

In that case you just apply an edge with a file and then just wipe off the burr with a coarse stone, or a finer file if you have the skill. You can also cut the bevel with a grinder, or a dremel, or even a high speed drill with grinding wheel.

[*]high speed blades obviously need a more obtuse edge angle than a manual blade, but durability is enhanced by a high sharpness, not lowered.

-Cliff
 
Nothing much to add to all the good posts^^^^^.
However do not forget to balance the blade after any type of sharpening.
You can make up a simple jig for this or buy a plastic balance that fits in the hole for a few dollars.
 
I'm certain that lawnmower blades today are softer than they used to be, due to product liability issues. They're made to be tough so they won't break or shatter, since we "consumers" hit all kinds of things with 'em.

Anyway, as Cliff says, a file is good enough if you're semi-diligent about keeping up with it. Save the Edge Pros and other good sharpening gear for blades that deserve it.
 
I saw an awful lot of smilies along with your question so I'm going to assume you are largely kidding us here. I moved up to the pine forest and gave away my lawn mower so I'll have to talk about past experience. I never had a mower and a grinder at the same time so I always used a file or a disk sander attachment and my electric drill. I would estimate the blades as being hardened in the mid-40's RC so they file well. The tough spots are where the blade has hit a rock and not only put a ding in the blade, that ding is cold work hardened.

The horizontal rotary mowers are pretty easy. What is a challenge is to work on the old reel style mowers. You would have something like 6 twisted blades that have to neatly come to the shear line of the stationary cutter bar. You think that scissors are tough...you don't know tough till you've sharpened an old lawn mower with a file! When I was in college I went from door to door sharpening things. I think I only sharpened two lawn mowers before I decided not to handle any more.
 
I use a Dremel to sharpen my lawnmower blades. They have an attachment that has a slot so the blade contacts the spinning abrasive wheel at the "correct" angle and you just run the tool the length of the blade to sharpen. Yeah, they're chisel ground, so you only have to do one side.

I don't worry about making them hair-popping sharp because the last time I stuck my arm under there to see if it would mow off the hair it cut my arm off at the elbow.

Lefty
 
mycroftt said:
I use a Dremel to sharpen my lawnmower blades. They have an attachment that has a slot so the blade contacts the spinning abrasive wheel at the "correct" angle and you just run the tool the length of the blade to sharpen. Yeah, they're chisel ground, so you only have to do one side.

Lefty
Click to expand...


Same here. Works great!
 
What are the chances! I spent my break at work shopping in three hardware stores for "something to sharpen my lawnmower blade!" ...then, after picking up a cone shaped attachment for my cordless drill, I come back to work, crank up bladeforums and "POW", a thread on sharpening lawnmower blades. ...and I get all this advice for free!!! This is a great country!

Thanks all

Bruce
 
Hmmm....nobody uses a file?

I have a Sears Craftsman mower, if the blade gets too bad I can get a replacement from Sears. Sharpened, balanced, and ready to bolt on.
 
Other than getting a replacement from Sears, I have found that it's pretty easy with a a file and less than 10 minutes of work.
 
I worked as a lawnmower mechanic and a 4 in disk grinder does a quick job sharp is nice but more important is blade tip speed for a good cut, 200 rpm low and the sharpest blades will still have a tendency to tear vs cut. We charged a flat rate for blades and mulching blades were 4.00 higher( we had a grinder designed for mulching blades, its cost $1800).If you have nothing better to do with your time, a hand file will do the job but you better have 2 or 3 spares sharpened before the mowing season starts or you will fall behind maintaining your lawn.
 
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