Lawnmower (Push) Blade Length

[honcho]

Thought I would see if I could use a new Scotts branded replacement lawnmower blade on a Craftsman lawnmower. I had the Scotts blade as a leftover to a mower that was discarded due to a bent crankshaft. It wasn't going to work on the Craftsman without a little work to drill some holes so the Scotts blade would fit the Craftsman blade adapter.

However, in my attempt to use the original CM blade as a template for the holes, I found that the the supposed 21" Scotts blade is only 20.5" long! 21" is the most common lawnmower blade length on gas powered push lawnmowers. The CM blade does measure 21". Using a 20.5" blade means that you are mowing about 2.5% less with each pass over your lawn. Mostly I just despise it when companies shortchange consumers with these little dimensional differences that they seem to use to increase profitability.

Oh well, live, learn, and spend more money........

 

[laser3kw]

looks like the right side is kind of eroded..
what the heck have you been mow'n?!

 

[larry_g]

Mostly I just despise it when companies shortchange consumers with these little dimensional differences that they seem to use to increase profitability.

Oh well, live, learn, and spend more money........

I bet buying a 2x4 just drives you straight up a wall.

lg
no neat sig line

 

[Infinia]

I don't think lawnmowers have universal standard sizes. I bought a replacement blade for mine MTD and it was a little too long, rubs the shroud under some conditions. BTW it also was about twice as thick as the original which I do like.

 

[honcho]

I bet buying a 2x4 just drives you straight up a wall.

Yeah, it does, especially when you're working on an old house where the dimensions are a lot closer to 2"x4"

A "universal" blade 21" blade is about $18 at Home Depot. The double "X" type genuine Honda brand blade is about $25 at Home Depot. In my mind, the Honda blade is a better buy. Of course, a Honda blade won't fit a Craftsman, even with a Honda engine (though I suppose you could fit the Honda blade adapter and make the honda work--maybe not given the multitude of mower engine crankshaft dimensions).

The Scotts blade is double sided with cutting edges on both sides. You can flip the blade over and have a new cutting edge. I can understand this not being possible on blades optimized for a particularly type of cut or discharge but kind of a nice feature. I'm not terribly picky about the finish of my lawn other than achieving a mostly uniform height but sharp blades do make the finished product look better.

 

[6PTsocket]

Thought I would see if I could use a new Scotts branded replacement lawnmower blade on a Craftsman lawnmower. I had the Scotts blade as a leftover to a mower that was discarded due to a bent crankshaft. It wasn't going to work on the Craftsman without a little work to drill some holes so the Scotts blade would fit the Craftsman blade adapter.

However, in my attempt to use the original CM blade as a template for the holes, I found that the the supposed 21" Scotts blade is only 20.5" long! 21" is the most common lawnmower blade length on gas powered push lawnmowers. The CM blade does measure 21". Using a 20.5" blade means that you are mowing about 2.5% less with each pass over your lawn. Mostly I just despise it when companies shortchange consumers with these little dimensional differences that they seem to use to increase profitability.

Oh well, live, learn, and spend more money........

If the Scotts blade is 1/2" shorter, overall that means each side is only 1/4" shorter. Lay one blade on top of the other and see how little difference there is.That is hardly noticeable.

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[rlitman]

If the Scotts blade is 1/2" shorter, overall that means each side is only 1/4" shorter. Lay one blade on top of the other and see how little difference there is.That is hardly noticeable.

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I suspect that you'll notice it a lot in suction and lift. I'd be pissed.

I also suspect that the non OEM blades will always be a little smaller because they're designed to fit more than one deck.

But then again I have a Honda mower (not just a Honda engine). And the Honda blades are always the same when I replace them.

 

[1saxman]

Lawnmower decks and blades are not standardized which is another way of trying to make you buy a certain blade rather than a generic. 21" blades go about from 20.5" to 21.0" with most being around 20.8". With a 'short' blade you're okay as long as the end gap is not too big but you have to check blade fit all the way around the deck because it may be out of round or have flats on the sides. Same for a 'long' blade; you need a little end gap so you just have to make sure it has clearance all around.
In your situation I probably would can the short blade and get a new one of the right size.

 

[6PTsocket]

I suspect that you'll notice it a lot in suction and lift. I'd be pissed.

I also suspect that the non OEM blades will always be a little smaller because they're designed to fit more than one deck.

But then again I have a Honda mower (not just a Honda engine). And the Honda blades are always the same when I replace them.

That is all we are doing, suspecting. I suspect that the pitch of the blade has a lot more to do with the lift than another 1/4" on each side. It is just grass chopping, not fitting pistons in a Corvette.

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[redmondjp]

That is all we are doing, suspecting. I suspect that the pitch of the blade has a lot more to do with the lift than another 1/4" on each side. It is just grass chopping, not fitting pistons in a Corvette.

That's your opinion, but you are wrong. Blade design has a huge impact on overall mower performance, especially when the blade and deck are designed to work together. I'm using a 1980s-vintage Homelite Super Bagger right now, and it's one of the best-bagging lawn mowers that I have ever used, period. It has a very special blade (only a few NOS ones left online so I bought a few) not available from any of the typical sources.

 

[Wakefield]

"Blade adapters" come in all sorts of variations specific to certain mowers and the crankshaft ends on the engines come in variations that don't fit some of the blade adapters 25 mm. vs. 1 inch vs. 7/8ths of an inch different keyways and internal tapped for capscrew hole/externally threaded/stud end
some blade adapters drop the blade height more than others