Industrial Grade Lawnmower Blades

T.Saslow

T.Saslow

Periodic Thinker
Joined
Jun 12, 2013
Messages
479
My grandfather recently approached me about some industrial or "Commercial" grade lawn mower blades claiming his friend was changing the blades on his mower and had a suspicion that they where good steel. I am aware that most mower blades aren't good steel, especially the ones from Home Depot and Lowes, however, I do trust his judgement in situations like this as he is an engineer who used to design mining equipment. I am wondering if such blades would be good steel for knives? I probably won't be making knives for customers with them but I suppose, if they are made with decent steel, they would make nice practice knives.

I don't know the specific brand but he did say that the mower they are from had 3 blades on it so i'm thinking this is a big mower :eek:

Thanks for your time,
Tanner S.
 
You already have one bevel ground! :)

Probably not worth the time to have them tested since without knowing the steel type, how do you ht effectively?

Pass
 
You can always do a quench test by hardening a section on the end and the putting it in a vise where the quench line is and then hit it with a hammer to see if it snaps off, confiming that it hardened. Use warm (about 130-150 degrees) canola oil as a quenchant first and see if that hardens it. If not, you can try water. If the oil doesn't harden it and the water does, it "might" mean that it has a lower carbon content, which would mean it's not all that great for a knife.

However, as many others have said countless times on this forum, don't bother wasting your time. Just spend a few bucks and get some 1084 from Aldo at the New Jersey Steel Baron. You will waste money in grinding belts (if you have a grinder or sander), other abrasives, other consumables, may end up ruining your sharp files and drill bits on steel that's not annealed, and you will be wasting your time And if the knife ends up looking really nice and you are proud of it, it will suck not knowing what the steel is and whether or not it will be a good working blade. Of course you can do a bunch of testing with it, and it may very well take and hold a good edge, but that will be a waste of time unless you have an endless supply of the exact same mower blades and plan on using them in the future on a lot of your knives

Spend your time and money using a known steel with a known 'makeup' that has been proven by tons of makers and users already, such as 1084, which is the easiest (most forgiving) steel to be able get a sufficient heat treat on using a homemade forge etc, since all you have to do is heat to non-magnetic and quench..

Without having a kiln to be able to program the exact temperatures and soak times that are needed for lot of higher alloy blade steels these days, or sending it out for professional heat treating, 1084 is your best choice. Other "simple" lower alloy carbon steels such as 1095, W2, 52100 etc. "can" be heat treated in a forge at home, but more skill and experience is required to be able to get the extra performance these steels can offer by being able to heat it to it's correct critical temp and to hold it there for a few minutes or so before quenching. If not heat treated properly, it is also lot easier to end up with an inferior heat treat using these steel than it is using 1084.

Sorry for the rant, but it's good to know these things, and since I'm not sure how much experience you have heat treating and making knives, I'm just explaining as if you don't have much by default :D Please don't take this the worng way, but your lawn mower steel question kinda hints that you don't have much knowledge in metallugy or heat treating etc.

So once again, spend your time, even your "practice" time, using a known steel. This way, while you practice forging and/or grinding and all the other aspects of making a complete knife, you can practice your heat treating along the way, which is one of the, if not "thee" most important parts of knifemaking. That way you can always buy more of that steel (1084) and continue getting better at knowing how to heat treating it for optimal performance. I'm assuming you plan on doing your own heat treating since it pretty obvious that you can't really send out unknown steel types (found steel) to get heat treated by professional, such as mower blades, old files, leaf springs, RR spikes etc etc.. So go order some 1084! ;)

~Paul
My YT Channel Lsubslimed
 
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Haha! I have been working on knives for a few years now. I use 1080 from Texas Knifemakers Supply pretty much exclusively. I just thought this may an interesting idea and I could use it to make semi-functional prototypes for knives I'll make in the future with the 1080 I have. Thanks for replying though :D

Nonetheless, I don't suppose giving Ye Olde oil quench, quick and dirty heat treat test could hurt...unless I burn off me own eye brows ;) I'll take the steel and see what i can do with it. Can't hurt to have some spare steel laying around....
 
xXBackyardCrafterXx said:
Haha! I have been working on knives for a few years now. ....
Click to expand...

Well dang man, now I feel stupid. :o lol

I should've checked your profile, my fault, my bad! :D

I get it though, sometimes ya can't help but to test out some "found steel" that looks/sounds as if it might be some good steel, It's all part of the fun when ya heat treat at home. ;) But I believe it's a bad habit to get into when someone is just starting out, which is why I wrote that novel above.. lol

~Paul
My YT Channel Lsubslimed
 
Yeah, I get it :) My profile isn't that well put together anyways so it's not your fault. Good habit to get into though-warning newbies of the dangers of found steel :) Who knows, maybe I could get my sister to test the steel for me...she is a chemist!
 
I have some "industrial" mower blades, and got max Rc60 in a brine quench at 1550f austentize. Played around for the better part of the day, and mediocre results at best.
 
Okay, I'll keep that in mind. By brine solution, do you mean water with salt added to it? What's the ratio?
Thanks!
 
xXBackyardCrafterXx said:
Okay, I'll keep that in mind. By brine solution, do you mean water with salt added to it? What's the ratio?
Thanks!
Click to expand...

I think I used a box of salt in a 5gallon pail. I haven't used it in well over a year, so I don't remember for sure. Hopefully Stacy will chime in. :thumbup:
 
I work in a repair shop for mowers and I don't think there really is a thing called "industrial grade" when it comes to mower blades most of them are about the same build quality with a little variation and a lot of advertising to make some seem better than others. Just my experience though.
 
I have been following this, and since everyone clearly knows my thoughts on lawn mower blades for knives, I haven't posted.

As for making brine quench, it is a 10% solution, so a pound of salt to a gallon and a half of water. is about right. Adding dish soap and other things may speed the quench rate...but just getting a fast enough quench to somewhat harden the steel does not make the steel good for a knife.

I chuckle a bit when people say that it is a "Professional grade" lawn mower blade. There are a few blades made different for some high end commercial equipment, but the vast majority ( probably 98%) of all mower blades are made to be tough and to resist breaking. The edges are supposed to deform and dent if necessary. That isn't what knives are made to do.

I understand wanting to use free stuff for making knives, but there just isn't any justifiable reason when the steel cost is almost nothing compared to the time and materials spent making the knife.
Are your time and skill worthless?
Is your equipment worthless?
Do your belts, sandpaper, files, handle wood, rivets, glue, etc. get delivered by elves in the middle of then night?
Do you want a knife made by you to be less than it could be?
 
Point taken Stacy. I am aware that most lawn mower blades aren't good steel for knifemaking but I didn't know there was such a small difference between industrial and Home Depot blades. Thanks for clearing this up. I still plan on testing it for fun, however I notice the overwhelming consensus is that it is not suitable for knives. Therefore, I will not use them on customer blades. I feel silly for thinking they where good for knives but I was told they should be good steel by my grandfather- an engineer in the mining equipment industry.
Thanks for your input Stacy, and all the others who have voiced their opinions.
Tanner S.
 
In your grandfather's day, they may well have been "good steel". In days past, any steel that was consistent in quality was "good". There weren't nearly as many alloy steels around, so things like lawn mower blades, car springs, and farm implements were likely some type of 10XX steel. Saw blades from mills were also likely to be "good steel". Today is a very different day.

Pull up a chair kids and Gramps will tell you why mower blades changed.
Life was simple in the good old days. The 1950's brought new prosperity to the USA. People bought houses in suburbs that had lawns. Then they bought their first real power tool....a brand new Briggs and Stratton lawn mower. It had a blade that cut the grass by itself. The blades used to be harder and sharper. Quality was an important part of how they were made. They were made at factories with American workers in places like Michigan .... from steel made in steel mills in New York. The guy who sold you the blade at the hardware store knew your name and probably went to your church. He put the mower together for you at no charge...and dropped it of at your house on his way home that evening. His kids went to the same school yours did.
Lawn mowers were simple machines with a 2.5HP motor bolted on a small platform with four small wheels. It ran on "Ethyl". To get it running, you wrapped a rope around the top of the engine and pulled it with a Tee shaped wooden handle on the end of the rope. It was pretty much open all the way around, but there was a discharge chute on the right side. A bagger was someone who worked at the A&P grocery. The blade was 14-16" long. Every spring, people took the blade off the mower, and sharpened the blade in the garage on a bench grinder. They stoned their blades regularly during the summer with long funny shaped stones called blade slips. Lawns were mowed by hand by the people who lived at that house, and mowers were pushed, not driven. No one was worried about getting sued if a stone was thrown at your neighbors house and broke a window, or a piece of blade chipped off. Toes were regularly mangled by people who stupidly pulled the mower back on their own shoes. They never tried to sue Briggs and Stratton or Western Auto because they were idiots.
When you wanted to go take a whizz or get a glass of lemonade, you just left the mower running on low and went inside.
Hit a rock or stump and the blade broke in half, shearing the mounting pins on the cast zinc blade mount. You got a new blade for $5-10 and a new blade mount for $5, went back home to fix it yourself, and were mowing again in an hour.

Then we turned the calendar one day and it was the 90's. Everyone had to sign waivers just to get their teeth cleaned. A new mower's owner's manual had ten pages of safety info and you had to bolt it together yourself. There were guards and safety lockouts, and people sued your butt off if their kid got grass thrown on him when he rode past you while you were mowing.
Hit a big rock or stump when mowing and the blade becomes a pretzel.... the shaft is bent....and you need a new mower.

I won't even get into what a joy working on a car was in 1950....when you and a buddy bought a 32 Ford for $50 and took the engine out in the drive way ..... and rebuilt it for $100 in the garage on a single weekend. Back then emissions control was a stock muffler ( which you threw away when you re-built the car).
 
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Those must have been good times. I'm not old enough to know what they where like but I have several tools I have cleaned up from back then. Amazing to work with. Makes me laugh when I see a ball-pein hammer with "Warning-Wear Safety Glasses When Operating" all over the handle and head....
 
Stacy E. Apelt - Bladesmith said:
I have been following this, and since everyone clearly knows my thoughts on lawn mower blades for knives, I haven't posted.

As for making brine quench, it is a 10% solution, so a pound of salt to a gallon and a half of water. is about right. Adding dish soap and other things may speed the quench rate...but just getting a fast enough quench to somewhat harden the steel does not make the steel good for a knife.

I chuckle a bit when people say that it is a "Professional grade" lawn mower blade. There are a few blades made different for some high end commercial equipment, but the vast majority ( probably 98%) of all mower blades are made to be tough and to resist breaking. The edges are supposed to deform and dent if necessary. That isn't what knives are made to do.

I understand wanting to use free stuff for making knives, but there just isn't any justifiable reason when the steel cost is almost nothing compared to the time and materials spent making the knife.
Are your time and skill worthless?
Is your equipment worthless?
Do your belts, sandpaper, files, handle wood, rivets, glue, etc. get delivered by elves in the middle of then night?
Do you want a knife made by you to be less than it could be?
Click to expand...


I have an industrial mower, made for landscaping companies and only use the factory blades. I don't use them for knives, because the steel I get from Aldo and Canadian Knifemaker is cheaper, is consistent in heat treat, and so ply works well. Even with experimenting with many variables, the best I could get was Rc60, inconsistently, right out of quench. I consistently get Rc66 or better with less effort with the known steels. I'm guessing the blades are probably something like 1040 with some nickel. They last a season on the acreage hitting rocks, scrap left in the grass by the dogs, bottoming out on hardened clay etc. might make a good hammer or axe, but I would rather buy a known steel for that and nail the HT.

If I came across as recommending mower blades, I'll make it clear here. Even the best blades would be mediocre for a knife. I could not get the blade to harden even to the post temper hardness I leave my known steel knives.
 
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