I have a 2 x 42 belt sander that works very well sharpening blades. I sharpen my co-workers blades often as it only takes me 5 mins max. This includes horizontal balancing and a finish nail in hole balancing.

I also do about 1mm x 45° on the bottom. Too sharp just rolls the edge over too easy. They love it.

As others mentioned, new blades are not sharp. I sharpen them before using.

Blades can definitely be hardened. The reason it isn't done is high risk of breaking instead of bending.

quote:

Originally posted by DonDraper:
My dad always claimed doing it with a proper file by hand was the best method.

Yup. This is the way I do it. Simple and therepudic.

quote:

Originally posted by ensigmatic:
Yup. Angle grinder, flapper discs, and an All-American Sharpener jig FTW. Add a good blade-balance tester and Bob's your uncle.

quote:

Originally posted by RogueJSK:
I've got a potentially better way: Replace them with factory sharpened blades.

A new pair of factory blades for my Honda mower is less than $30.

The blades for my commercial-grade ZTR mower cost considerably more than $30 each, much less per pair.

Someone agrees

^^^ Guess video guy doesn't know about a flappy disc?

quote:

Originally posted by doublesharp:
^^^ Guess video guy doesn't know about a flappy disc?

His review of the AllAmerican (using grinder with flappy disc) starts at 3:00.

I watched and skimmed right over the review when I saw the assortment of bolts. Did not know what he was doing - mine is not that complicated. I've got a dedicated wrench for grinder and just hold the mower blade in my hand.

Whenever I buy the next new mower I’m just going to suck it up and buy a second set of blades right away. I’d rather sharpen them when convenient and have them waiting. I’ve used a flapper disc and it did work just fine. I really don’t have issues with rocks just ordinary wear.

quote:

Originally posted by Oz_Shadow:
Whenever I buy the next new mower I’m just going to suck it up and buy a second set of blades right away. I’d rather sharpen them when convenient and have them waiting. I’ve used a flapper disc and it did work just fine. I really don’t have issues with rocks just ordinary wear.

This is what I’ve done for years. Have a second set ready to go. When it’s time to change a quick 2 minute swap and I’m back in business. Sharpen the old set at my leisure.

^^^ About to perform my mid-season blade swap and install my presharpened spare blade (long mowing season in Houston).

An optimization that I've made is that my sharpening session for both blades coincides with the lawnmower's annual oil change. Have to tip the lawnmower over for both so might as well combine them.

quote:

Originally posted by Oz_Shadow:
Whenever I buy the next new mower I’m just going to suck it up and buy a second set of blades right away. I’d rather sharpen them when convenient and have them waiting. I’ve used a flapper disc and it did work just fine. I really don’t have issues with rocks just ordinary wear.

I bought a 9-pack of blades for about 1-2 per blade cheaper than I could buy 3. I swap them & stack the dull ones up until I have time to sharpen, then paint the edge so it won't rust/don't forget it's sharpened already.
I have a set for granny's mower too. When she calls, I only have to tip the mower up, zip off the bolts & swap.

I don't find a need for a guide/sharpener on mower blades, I'm not shaving with them & I leave the edge thick & sorta convex. I have a $20 vise that I bolted to a 2x6, throw it on a sawhorse & pop the blades in. Takes longer to drag the sawhorse around & reposition blades than it does to sharpen.

For those who are not inclined to DIY, I suggest ACE Hardware.

Since this thread started it got me working on the JD, it was due for its big service, oil, filter, air filter, plugs, grease fittings so decided to pull the blades, didn't get a before picture on the blades.

Local ACE chain has several stores with the ability to work on the Sthil products they sell as others and they sharpen blades.

Dropped of before closing at 6:30 PM Sunday, ready before noon the next day. $5 bucks a blade. They are sharp! A few seconds with the impact and it's back together...