Lawn mower blades

[Mike Brubacher]

I may have just sharpened my first lawn mower blades intelligently. I'm back on the farm now and mower blades take a beating here. Heretofore, mower blade sharpening has been the province of bench grinders and it's an ugly process. Here's a picture of one blade segment prior to sharpening;

                             

The picture really doesn't do justice. The edge apex looked like it was 1/16" wide and perfectly rounded. Would have measured about 20,000 on the BESS I'd estimate. I've got one of those Harbor Freight 1 x 30's here and thought this would be a good opportunity to make use of it. I put on a 120 grit ceramic belt and removed the big end of the notches that had dented the edge first. This was accomplished by holding the edge perpendicular to the belt. I'd guess the bevel at about 30° so shined that up and thinned it just a bit. I didn't want to use up 16 belts and frying by belt grinder in creating a burr so tipped the blade back about 5° and put a micro bevel on it and raised a burr. Then just a  light touch on the back side.

On went the SFN Scotch Brite belt then for about 5 light passes per side. Here's the finished product;

                               


413 and the burr is gone. That's just about where I wanted to end up. Now we'll see how it works. Sure looks better than a bench grinder job though and was pretty simple and fast to effect.

If you're interested in the crop report, here's what the soybeans look like this year around here;

                               


Scenes like this make an ol' farm boy's heart swell.

[SteveG]

Nice picture, makes me want a farm.

Do you need to balance the lawnmower blades when you sharpen?

[Mark Reich]

Looks like y'all had a bumper year down there too, Mike. I can't recall the last time we got a solid third cutting on all our dry land.

Mowing the lawn is different for farm boys. Running the lawn tractor is fun for a 6 year old, but you have a few acres of "lawn", with all kinds of buildings, grain bins, and at least dozens of trees. 

I'd estimate the fun lasts for about one season. After that, it's pretty clear that mowing is not as fun as about a hundred other things you could be doing, and by the way, you're now in charge of maintaining that piece of equipment. 

Of course, I was instructed to sharpen the blade with a file. Years later I discovered that files were not actually made out of pure rust, and things got easier.