Making a knife from a circular saw blade..

Ryan Mooney

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My understanding was that most saw blades (not counting stuff with carbide tips which are a whole nother beast) are differentially tempered so the tooth side is generally harder than the center. So I think this would be a bit of a dice roll on what kind of hardness and edge life you'd get out of the blade depending on where in the original blade you cut it out of and how that was hardened (and might vary substantially throughout the knife even). Re-tempering it would be the usual dice roll working with steel of unknown provenance but probably moderately safe to treat it as oil hardening and do a few tests.

If you were real clever and knew what was what where (maybe using something akin to these to check the hardness https://www.amazon.com/TSUBOSAN-Japan-Hardness-Tester-Checker-HRC40-HRC65/dp/B000TGHFLC) you could probably use that to your benefit and put the hard side towards the edge/tip and the softer bits further back towards the top/handle of the knife so as to make the parts you want stronger stronger and the parts you want more flexible/tougher more flexible/tougher. But it's probably easier just to re-temper so you know :)
 

Bruce Haugen

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I had several worn out saw blades made by Leitz, a German mfg. I called their Wisconsin office and learned that the plates were made from 1040. Can’t answer for other manufacturers, though.
 

Ryan Mooney

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I had several worn out saw blades made by Leitz, a German mfg. I called their Wisconsin office and learned that the plates were made from 1040. Can’t answer for other manufacturers, though.
Interesting, I hadn't actually seen a verified steel type before for those. Can I ask - were those with carbide tips or did they have just cut steel tips? I'd have thought 1040 would be a bit low carbon, but maybe hardened hard enough it would stand up ok as a circular blade steel?

I'd be more likely to use 1040 for something like a hammer or maybe rock splitting wedges than a knife blade or similar.. it would be real tricky to get properly hardened with that low of carbon (not saying it's not doable.. but as for the backyard amateur... it would be real difficult) and I don't think it'd hold an edge very well even if you were good at it compared to cheaply available stuff like 1095.
 

Bruce Haugen

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Carbide tips. Its relatively low carbon, but apparently you can get it hardened to something like RC 56 or so. I made a decent shop knife from it, and a friend heat treated it. It holds a decent edge. I also made a couple marking knives. I wouldn’t use that steel for anything I prized highly.

25 years ago, I made a Bowie from OCLS (old Chevy leaf spring) which is actually 5160, and it takes a wicked edge. It’s right at RC 58. That one was differentially hardened by an ABS master.
 

Ryan Mooney

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Carbide tips. Its relatively low carbon, but apparently you can get it hardened to something like RC 56 or so. I made a decent shop knife from it, and a friend heat treated it. It holds a decent edge. I also made a couple marking knives. I wouldn’t use that steel for anything I prized highly.
Verhoeven shows 1040 maxing out at 52-54 depending on the specifics and treatment https://archive.org/details/Metallurgy_of_Steel_for_Bladesmiths_Others_who_Heat_Treat_and_Forge_Steel_By_Joh/page/n157/mode/2up - pg 155). I suspect its likely a bit brittle around there and likely hard to get it to get that hard very deep into the metal as you'd have to quench it pretty fast to hit the mid 50's... Maybe a blade is thin enough it would mostly through harden.. I'm not sure.. That might actually be mildly advantageous for something like a shop knife though as the rest of it should be fairly ductile so it's less likely to crack if you drop it. For things like marking knives and the like that aren't worked to hard (and you want to have been easy to touch up..) it's probably a decent choice alright (y)

He also claims that 5160 is easier to through harden so you'd have a more consistent performance there as well. He actually has a lot to say about 5160 .. some of which I sort of half understand :whistle::oops:. Looks like getting a consistent Rc58 out of it would require a good long heat soak and I suspect that that's right around the upper end of where it ends up turning brittle if you're not real good at it. Having someone differentially harden it probably got you a really nice knife (y)(y)
 

Bruce Haugen

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as you say, it’s a decent choice, especially since it was free :cool: The blade is thin, maybe 3/32”, obviously less than the saw kerf with carbide teeth. It was/is a practice blade, and for its purpose, it’s good enough. For things like A2 I have them done by a pro, temp controlled oven soak, air cooled, cryo treated.
 

Ryan Mooney

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I've never even tried A2 :oops: Having a pro handle it seems more than entirely reasonable. In general though I've mostly started leaning harder towards ease of sharpening and simpler steels for most things (lathe tools mostly excepted...).

I've done a few things out of really old files (some sort of plain high carbon.. worked decently with out), some O1, a couple of springs, and a few other random similar bits. But that's about it... and that's been a while.

I have a bunch of planer blades that I'd like to know what they are... they seem very thoroughly through hardened (yes I can grind them.. but not quickly or easily). Seem to hold temper pretty well even when I mess up and get them a bit hot and they work really really well for lathe scrapers and yard knives and the like.
 

Vaughn McMillan

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I realize that experimenting and working with the metal is part of the allure for a lot of guys, but I prefer to just buy pre-made blades and put my efforts into the handle. There are some nice blade options available out there for not a lot of money.
 

Mike Stafford

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I have a number of 10 and 12 inch saw blades, non-carbide in my shop that measure a hair less than 1/8" behind the teeth. I wonder if any of that steel would work for a knife.

I really enjoyed this video. I enjoy seeing fine craftsmen do fine work and this is an example of fine work.
 
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Bruce Haugen

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I've never even tried A2 :oops: Having a pro handle it seems more than entirely reasonable. In general though I've mostly started leaning harder towards ease of sharpening and simpler steels for most things (lathe tools mostly excepted...).

I've done a few things out of really old files (some sort of plain high carbon.. worked decently with out), some O1, a couple of springs, and a few other random similar bits. But that's about it... and that's been a while.

I have a bunch of planer blades that I'd like to know what they are... they seem very thoroughly through hardened (yes I can grind them.. but not quickly or easily). Seem to hold temper pretty well even when I mess up and get them a bit hot and they work really really well for lathe scrapers and yard knives and the like.
Ryan,
George Wilson on SMC has written that the old files were made out of W1, about as simple a steel as you will find. It hardens well and easily, too, and since it’s water hardening, pretty simple to handle. I’ve made small stuff from it, they take a really good, fine edge.

I’ve read that many planer blades are made from M2 and M4, very tough but very difficult to heat treat. If you’re careful in grinding, you can make stuff from it without losing temper.

I know that Stephen Thomas, maker of the Loopy Plane, prefers M4 for his plane blades because it takes a wicked edge and holds it forever. He has HT equipment and knowledge of that, though.
 

Ryan Mooney

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I'm pretty sure the ones I had were W1 or something very very similar based on how they behaved. I tried working with a newer one and turned it into something very much like glass that didn't survive even to get tempered so it must have been an oil hardening or ?fancier? steel. Pretty neat to see how it shattered though :ROFLMAO:

I could see the planer blades I have being something like M4, I think it's harder/tougher than the M2 lathe tools I have... although that may well be because of the treatment of them as well so hard to know. It's also harder to grind than A2. Either way I believe its some sort of HSS as it holds hardness really well even if somewhat over heated.

For hand planes.. idk... I can see the appeal of the really tough stuff if you're working with extra miserable wood. I had a piece of black locust that would put literal grooves in old stanley blades, so for something like that an M4 or similar blade would be delightful. But OTOH wood like that isn't really delightful to work with anyway for other reasons so on easier woods.. I'm kind of well into the "quicker and easier to sharpen" camp at this point. I've tried a couple fancier blades but they're tedious to sharpen in comparison and sharp is less work.. so ultimately there is some value of lazy that kicks in :)

I watched the video last night after I made my previous post. I can see how the metal process would be fun. :thumb:
Even more so with a forge :cool: I miss having a forge!
 
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