# Lawn mower blade as tool steel?



## jtriggs (Dec 13, 2007)

I've heard of using old reciprocating saw blades as a source of thin tool steel. What would be the result if you used an old lawn mowing blade for a thicker profile? It would seem to be a cheap alternative to going and buying tool steel somewhere.

Thanks for any advice.
Jon


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## scotsman9 (Mar 25, 2013)

Lawn mower blades by standard are made of extremely soft steel. They have to bend and dent when hitting rocks and other hard debris. If they were made of tool grade steels, they would shatter and become missiles. So, manufacturers make them with soft soft soft steel.

I'm not quiet certain, but I think the Feds of an allowable hardness for lawn mower blades.

???


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## Nomad62 (Apr 20, 2010)

There're just not the same thing, kind of like brass vs bronze; there are differing amounts of carbon (in the steel) in each, and they are made and formed differently. You could never get the soft metal of a mower blade to do the work of tool or stainless steel.


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## Buckethead (Apr 14, 2013)

I've heard the Egyptian Great Pyramid's stones were cut partly using copper tools, but then again, I've also heard they were built by aliens.

So as long as an alien is wielding the tool made from the softer steel, it should be fine.


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## crank49 (Apr 7, 2010)

My former employer makes cast alloy iron with a hardness that surpasses most tool steel, Rc 62 to 65 but is used in blow bars and hammers for hammer mills. These wear parts are designed for extreme hardness and impact resistance. Hardness does not directly relate to toughness and impact resistance.

Also, generally stainless steel is softer than even mild steel, with the exception of the 400 series. And the 400 series, although it can be hardened to Rc 60 or so, is a nightmare to sharpen.

Anyway, the blades of a rotary mower are designed for toughness and not necessarily hardness, as was already stated. But, it is possible they could be hardened by heat treating.


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## bondogaposis (Dec 18, 2011)

It depends what you want to make with it. A similar sized bar of O1 tool steel from Mcmaster Carr might cost double what you could buy a lawn mower blade for, but it will be all useable, with out all of the bends etc. The nice thing about working w/ tool steel is that you can do all of the shaping, drilling, etc. before you harden it. Where as if you have ever tried to drill a hole in reciprocating saw blade you know what I am talking about, impossible.


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## waho6o9 (May 6, 2011)

http://www.harborfreight.com/5-piece-m2-high-speed-steel-mini-tool-bits-for-metalworking-lathes-40641.html










Here's a good alternative for a good quality HSS that's cost effective.


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## Finn (May 26, 2010)

We used top use old auto leaf springs to make tools with.


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## jtriggs (Dec 13, 2007)

Thanks everyone for the swift replies. You're right of course, I've seen enough dented blades on a mower to know that is softer than tool steel should be. Thanks for the other suggestions.

This is the smartest place on the web.
Jon


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## TimScoville (Apr 8, 2009)

During my trips to Asia, it was common to see lathe tools made from steel files as these are normally hardened and keep an edge pretty well.


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## casual1carpenter (Aug 16, 2011)

Jim, we have used leaf springs also, but you can not be real aggressive with grinding and shaping, as they can become brittle. Also without real information and actual material specifications you would need to be mindful of things not blowing apart before your very eyes. Some how I'm thinking lathe tools and a brittle type failure here. I came with two eyes and other various body parts and would really like to keep them.


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## Loren (May 30, 2008)

I know swordmakers make swords from them. I don't
know if they hold an edge though… these days most
handmade swords are made for show and aren't
sharpened for safety reasons.


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## jbald (Dec 11, 2011)

As a rule, if you can file the metal than it's soft steel (lawnmower blades are sharpened with a file). If the file slides across without removing material, than it's hard. Of course soft steel can be hardened by heating and quenching (machine shop 101). In general all old handsaws, circular, band and hack saw blades are good tool steel as well as old files. Gardening tools are not hard with the exception of the machete which is good spring steel. Don't overlook old putty knives and scrapers which are also hard.

Do I have to say "never use scrap steel as knives, in powered rotating equipment? (homemade junk kills people).


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