lawn mower steel for knife?

A

Alan Molstad

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I think I read in BLADE mag about a year or two ago that at a cutting competition one of the higher finishers was using a knife forged from a lawn mower blade.

I talked about this with a family friend, and he started to collect a few of his left over blades for me to use.
Now the other day he handed me some, and suggested that I might make him one from one of his own blades.

Knowing that one guy did well in a cutting competition in BLADE, I decided to give the lawn mower blade a try.
I forged it to shape, and heat-treated it, and tempered it as if it were 5160...(Because thats all i know)

The resulting blade does not appear to be hardened.

The file does not skip over the edge and make that "glass" like sound as I have heard with hardened 5160

so....this is never going to work?
 
Alan,most mower blades today are junk :( If you find the really expensive ones that they use commercially or in agriculture you might get something good.
On the plus side I can hit a rock and fix my mower blades without messin up the ht :)
 
Thats an important thing to keep in mind. My own lawn mower has a life that must be hell. I mow a very large yard, and I hit all kinds of stuff all the time.

I dont even try to drive around most rocks and cans anymore. Yet the blade never breaks. It does get dinged up a bit, but it never breaks.

It may be junk steel, but it is not breaking and thats good too.

But I take it that it will never get hard in a quench?
 
My guess would be that the steel used in modern lawn mower blades would be of the low carbon variety. I run over everthing in my path, no breakage here either. Just small dings. I think the manufacturers make them soft, to reduce injury from flying bits or chunks of broken blade. That's just my theory on lawn mowr blades. My BIII sure makes short work of resharpening them though! :D
 
Then we return to the BLADE story of a guy who came in 2nd or 3rd in a cutting competition with knife made of a lawn mower blade...

If the guy used a normal lawn mower blade with the same steel as is on our mowers. then, why did he use it?
 
I can only speak from my own experience, but the mower blades I've forged get screaming hard when quenched. I think that the biggest problem of mower blades is that each company has it's "secret" alloy, so you never know what you have. If you have a steady supply of the same stuff and take the time to test and figure out what works best for that steel it's worth doing.

Either way, if it hardens and it's cheap (or better, free) it's good enough to learn bladesmithing with IMHO. Once you've decided that 'smithing is something you want to do and you've gained some skill, definitely go for known steels. For practice though I personally have no problem with "mystery steel".

Just my $.02.

-d
 
My brother gave me a long roller type bearing from a copyer.
He said that after checking, the steel of this long bearing was made of "High Carbon" steel

I forged it 2 weeks ago into a blade.
Tried to quench in oil....didnt get hard
Tried to quench in water....didnt get hard.
 
I must say free steel is very tempting but some times is more of a problem than its worth. you can spend 10 hrs on a knife that will never be good for anything but just looking at. But with the price of good steel its worth getting some good O1 or 1095. i have been caught in this trap befor and its not worth my time to mess with steel that im not shure will harden. but if your just learning and wanting to practic then use anything you can get.
 
I havent made many knives and am by no means an expert.
A maker a recently spoke with gave me some good advice.He said to forge a thin section or if it's already thin(mower blade) take a 1 or 2 inch strip of steel and heat treat it as you would your knife,maybe even slightly bevel it too.then do some hardness testing IE: file bite,bending/breaking.According to him a nicholson brand file is RC 57 so if it bites then you are below 57.

It sounded good to me....anyone is always more than welcome to correct me with a cyber slap :p
 
thats a good idea, gives you an idea of what your working with. i know some cheep files are just case hardened but have the aperance of being good steel to make a knife from.
 
Alan, are you sure that you are not burning the carbon out of these trial blades, by overheating when forgeing, or heat treating?
 
but it does make sence that there low carbon, because when you go to sharpen then thers lots of dents not chips. if you need forging steel i have a bunch of HC RR spikes. but if you think about it a hardened lawn mower blade could be a very big hazard, could you imagin going along and hitting a rock and having the blade snap in half. with the speed its moving at it could go clean throught the side of the mower and take your leg off.
 
I hammer on HC RR spikes all the time.

At work.

Driving them into RR ties.

That's the best place for them!

Mike Blue did some research and found out that the "HC" spikes are indeed higher carbon than most, but only around .33

That's not much!

IMHO, you are much better off to buy a 20' bar of tool and or spring steel for an amount way too cheap to mess around with the other stuff.
 
IMHO, you are much better off to buy a 20' bar of tool and or spring steel for an amount way too cheap to mess around with the other stuff.
Click to expand...

I think Nick hit it right on the head with this one. High carbon steel and some tool steels are cheap enough to buy and learn with. Besides, if you give a knife of "mystery steel" to a friend, or sell one cheap to a customer, are you really certain of what they are getting? Are they getting your best workmanship and materials? Lets face it, if you don't know what steel it is, you may not have heat treated it properly, then you may spend weeks wasting time futilly trying to figure out what went wrong, if/when it broke, cracked or otherwise malfunctioned.

Customers deserve the best a maker can give. It makes sense to know the steel and the heat treat process for that steel well enough to give the end consumer the best you've got.
 
LRB said:
Alan, are you sure that you are not burning the carbon out of these trial blades, by overheating when forgeing, or heat treating?
Click to expand...
No Im not sure.
I heat treat the lawn mower steel as if it was John Deere 5160 because thats all I know how to do.

I heat treated the bearing from my brother the same way too, yet even in a water quench the steel is far too soft to finish.
The file digs into the hardened edge.

There is always the chance that I might have overheated during the heat/quench because I am always unsure when to pull the trigger, when to dunk.

But I dont think I overheated during the real forge work as I tend to be in a hurry and forge as soon and as fast as I can between heats...
 
I've played with a couple of different lawn mower blades. Some older ones are red short and can be hardened in oil. Some newer ones act like something around 1050 to 1080. Haven't tried heat treating any of those as I decided if I give, trade or sell a knife I should be able to tell what steel ii is and be sure it will last and work.

If you want to try a lawn mower blade knife, start by learning what heat treat will work for it. Use sections 2-4" long and as thick as your intended knife. Try different quenchants and tempering cycles. Check your quenching temperature and if judging by color make sure ambient light is the same for each test.

ron
 
Anybody thought of calling a couple manufacturers and asking what steel they use in their blades? Or an email? I bet they would tell you.
 
Sorry, I meant to put a few smilies in my post above.

I do honestly feel you're better off to buy some tool or spring steel. You can get a 1/8" X 1" X 20' (or so) bar of many different grades for cheap at places like Pacific Machinery and Steel in Portland, OR.

But I didn't mean to come off as condescending about it either! :o

Trust me, I know how intriguing and cool the idea of mystery steels can be. But it's like that mystery woman... It may look good on the outside and seem like a good idea at the time, but there's no label on the box and you might just be getting into trouble! ;) :D

-Nick-
http://www.wheelerknives.com
 
LRB said:
A Nicholson file is at least 65 Rc, or more. It is certainly not 57.
Click to expand...

I never was a wordsmith:o the way it was explained was that the file itself wont bite above RC 57 .I dont even want to mess my head up trying to get all those numbers in there.My brain is like tetris it all sinks in better slowly ;)
 
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