Lawn mower blades

I've seen someone here report on doing it just that way for commercial mowers.

Given that the blades seem to be fairly soft (and that they need to be, as one may not want one's blade to fracture), trying to get the World's Sharpest Edge on one's lawn mower blade may just be a waste of time after the first 100 blades of grass get cut.

I saw one of those programs on cutting devices, and the blades for those machines that eat anything were sharpened with some very simple grinders mounted at the proper angle.

But then, how would one test the proper angle on an actual lawn, and how would you know when you had it just right? I'd say that close enough would be close enough, even with a hand held sharpening device. At that rpm, even a blunt edge would cut, but definitely anything with any angle would leave a little cleaner looking lawn, and perhaps even produce a more shredded mulch.

Steve

Soft? I don't think *that* soft, and a super-TOUGH material.... holy shit.....

I think the op's complaint about grinding is precisely because these blades ARE so tough!

Milling, I think, would be fine, but my lawnmover blades seem to have some complex angles and twists. But if you can set up your machine to do it, and it doesn't eat up yer end mills, then it might be a good strategy.

Mebbe clamping the blade in a bench vise and having at it with a 4 1/2" angle grinder would be effective, as well. As time alluded, you don't need a chef's edge here.

Try it. Let us know if it saves time. My guess is it will take longer unless you got a nifty quick way to mount at an angle. Of course, I have a nice six inch bench grinder with a coarse stone. If you got a smaller grinder, the mill may come out faster.

Tim Wescott fired this volley in news:ibSdnfQjcb- t6FXQnZ2dnUVZ snipped-for-privacy@web-ster.com:

That'd be me.

Oregon makes the blades for the Scagg 61" commercial mowers. They are _adamant_ about milling them with a face mill rather than grinding them.

They supply them as new milled, and they specify the angle and remaining width of cutting backup area for new milling. Until they become narrower than spec, you just keep on milling new faces. I get about 30 acres per sharpening for a three-blade set now, up from my original 18. It has more to do with the fact that I've finally cut up and and not now re- cutting all the thatch than with the method.

I built up a permanent angle jig out of a block of 6061 to hold mine, and use a small carbide insert face mill to produce the edges.

One benefit is that it never overheats the metal. The other is that they come out virtually perfectly balanced every time.

LLoyd

Many years ago when I was clearing property with a Gravely two wheel tractor, I used hard surface welding rod to build up the cutting edge of the 30" mower. Never had to sharpen that blade again. One time I hit a piece of RR track buried in an anthill. Busted a two inch chunk from the RR iron but the blade did not even get a nick. Been 45 years ago and I do not remember what rod I used, just that I used an electric rod but applied it with a torch.

It will probably work, but I can't see it being fast.

Try an angle grinder and discs rather than a bench grinder. Works way faster for me.

There's no need, or use, in getting every nick all the way out - you go mow, there will be new nicks.

Belt grinder would probably also work faster.

I just use a file, doesn't heat up the steel, doesn't take _that_ long.

Yeah, I've used both, but now I only use a little 4" angle-head grinder. The wheel isn't quite as cool-cutting as a coarse wheel on a bench grinder, but it's so much easier to hold the right angle, and to see what you're doing, that the job goes much faster even though you have to let the blade cool after every few passes.

Not that the stuff they make blades out of is likely to suffer from some overheating, but I just hate to see that blue color on steel while I'm grinding it.

Actually, it sounds brilliant! I once spent almost two days standing in front of the bench grinder making a blade from scratch out of a piece of spring steel, 3" x 1/4" (about the size of a mower blade). But I admit I'd be a little reluctant to cut spring steel on a mill; but ordinary A36 or even O1 should be a snap. And you could get that "hollow ground" effect by using the right size of ball end mill. :-)

Have Fun! Rich

I have 20" carbide blades on my 21" self-propelled mower. I thought I would try them before spending $90 on a set of mulching carbide blades. I am not sure if they are available anymore.

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I'd start with 20 degrees (I think) - that's the angle you're suposed to hold your Boy Scout knife while stoning it.

But I once bought a mobile home that came with the mower, and the blade was BLUNT! A buddy across town had a wheel that he mounted in his hand drill, and eyeballed it, and it made a world of differencce!

Cheers! Rich

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My lawn mower blades get dinged up real good by sticks and small rocks. Grinding them takes me a long time, 2 blades, 4 edges. Is there any reason why I couldn't set up the angle in the mill and clean them up with an end mill? I would think this would be a lot faster. I could always grind in the final edge.

If this isn't a good idea, then everyone should forget I asked a stupid question.

Wayne D.

Well, yeah, if you sharpen the blade about once a week. ;-)

Cheers! Rich

I just use a brush hog first.

Belt grinder with a coarse belt fixes mine up in short order. Lotsa rocks... Don't need a scalpel edge for whacking grass, a 40 grit one works just fine.

Stan

Slightly off-thread:

I once had a 30" Gravely mower with a monster blade: about 3/8" thick by 3" wide & 30" long. As the end kept getting narrower and narrower from sharpening and I put off buying a new one ($$), it occurred to me that I could make it into a flail mower by cutting off the narrow ends and bolting on short flails. Those flails could even be pieces of 21" mower blades, which could be had for no cost (dump).

I sold the mower before I had to do anything about the blade, but would the conversion-to-flail have been a good idea?

Bob

I think you would waste a lot of blade material by milling. The problem that I have is that the tips of the blades wear away faster than the rest of the cutting surface. So one straight cut won't do it. I have 2 old Cub Cadets with 3 blades each to sharpen. I simply use an old 6" bench grinder. That way, I can sharpen the worn tip by following the worn edge by eye. BTW, if I am feeling particularly cheap, I heat the tip and forge material from the back side of the tip toward the front to give me an extra year or two of use--- just like they used to do to "sharpen" a plow share.

Pete Stanaitis

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"Pete S" fired this volley in news:d8GdnawRl_EyCFfQnZ2dnUVZ snipped-for-privacy@bright.net:

That's why the acceptable profile may include an angle from inside to tip.

Yes, you remove more metal by milling than by "selective" grinding, but there are advantages.

One: once it's jigged up the first time, it takes only two or three minutes to mill the ends, and the blades are usually spot-on for balance after. Two: A "hollow grind" was suggested here... that's wrong on a mower blade. When so done, the edge wears faster, and the "shoulder" at the back of the hollow erodes quickly if there's any sand in your mowing field. Three: It's what Oregon recommends for optimum cutting with their blades.

I get roughly 30 acres per sharpening -- that's five mowings of the area I mow weekly. A blade lasts through about 10-15 sharpenings.

So, I get more than a whole year's worth of mowing from one set of blades, and a new set of three is about $40. For me, at least, it's worth it to get that "golf course" look in the front of my property.

I have three "working" sets used in rotation, so I don't have to stop for sharpening, if I decide they need it. It only takes five minutes to change a set of blades on the Scagg 61" deck. Except for dropping the blade bolts out of the spindle bores, it's all done from the top of the deck, with no removals or loosening of any other components.

LLoyd