Using old saw blades from a sawmill for knife steel

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Maineiac1

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Hello I know of another local to me knife maker who strictly uses old sawmill saw blades for his knife steel. I was wondering what the professionals thoughts are on the quality of the steel? I know your not going to know exactly what steel its made from other than a high carbon. But since he does not heatreat it, is there any worry for bad steel? He told me he uses a plasma cutter and a grinder to cut out the knife shape and bevel a cutting edge. Would this temper the steel beyond a good hardness? Would these saw blades have been exposed to overheating during use? I'm all for buying others knives but I'm not sure as a newer knifemaker whether this is good practice or not where I may get a knife that cant hold an edge.

Steel is from an old sawmill and is 1/8" thick
 
Some sawmill steel is just fine, when heat treated. Some isn't. Whatever he's working with, doing it the way he's doing it is going to result in crap. Better heat treat it if you want a decent knife. Plasma cutting, grinding, etc, will ruin whatever HT the steel may have had.
 
So plasma cutting will have some effect on temper, for some distance, depending on the cut speed this could be 1/16" or it could be 1/2". Also, the heat is drawn away very quickly, so it will temper less than a soak at that temperature. Still not good. Even so, he could be gand grinding away the heat affected zone (HAZ).

The bigger problems I see are:

1: It would be SLOW to grind all your bevels in on a knife of that size without affecting the HT. Based on his somewhat tenuous relationship with the importance of a good heat treat, I suspect he doesn't really care.

2: The saw blades are almost assuredly tempered significantly softer than you would want for a knife. These blades tend to be very large in radius and treated roughly. They need a huge amount of shock resistance that one doesnt get in the standard teper ranges for knives. Also remember that steel saw blades are/were regularly sharpened with files. That alone tells you they are overtempered for the purpose of being a knife.
 
Buying new steel with known composition is always better. You know exactly what it is and can HT properly. Steels probably better than the old stuff.
 
Don Hanson III said:
The original heat treat of saw mill blades is not hard enough for good edge holding.
Usually in the upper 40s' to low 50s'.
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That's what I was thinking so its good to hear it from someone who also uses this method but properly. And thanks for everyones input.. I will stay away from his knives.

I have recently made a knife from a wrench but I heat treated it once I rough beveled it. Seems so have taken a good heat treat but I'm unsure the hardness.. My thoughts when using mystery steel is to heat treat and test where this other maker says "I make sure not to overheat the steel while working"..
 
Yeah, I figured that most would be 15N20, 10xx or maybe 8670 and not L6 like some think. The popular but generally unavailable 115W8 was used for metal cutting bandsaws before being replaced with HSS. It's cousins like 1.2519 seem to get used a fair bit in the timber industry nowadays.
Don Hanson III said:
The larger band saw blades (6-12" wide) test out as 15N20, but tried a smaller one years ago that had no nickel, it was 1075. Hardness is always around 47 rc.
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jdm61 said:
Yeah, I figured that most would be 15N20, 10xx or maybe 8670 and not L6 like some think. The popular but generally unavailable 115W8 was used for metal cutting bandsaws before being replaced with HSS. It's cousins like 1.2519 seem to get used a fair bit in the timber industry nowadays.
Click to expand...

Last autumn I finally found which steel was this circular saw ................https://www.bladeforums.com/threads/circular-saw-for-wood-steel-identification.1438309/
It is Turkey made saw from German steel . I contacted them and ask ................answer was that it is 1.25 % C and 2 % tungsten steel :) It is very close to this 115W8 .
What I don t understand is why they leave that much soft blade /46hrc/ because steel is very tough ?
PS . They cut 100 cubic meters oak for firewood with this circular saw before they need to be sharpened .
 
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Thats sounds like a batch of 115W8 with a bit of extra carbon. That is in the same neighborhood as Hitachi Blue #1 but maybe still with more tungsten. Do you know how much chromium it has? "Standard" 115W8 appears to have around .25% whereas the Blue steels have a bit more.
Natlek said:
Last autumn I finally found which steel was this circular saw ................https://www.bladeforums.com/threads/circular-saw-for-wood-steel-identification.1438309/
It is Turkey made saw from German steel . I contacted them and ask ................answer was that it is 1.25 % C and 2 % tungsten steel :) It is very close to this 115W8 .
What I don t understand is why they leave that much soft blade /46hrc/ because steel is very tough ?
PS . They cut 100 cubic meters oak for firewood with this circular saw before they need to be sharpened .
Click to expand...
 
This is an old thread, but I feel it is worth a quick post to note that while sawmill blade steels are indeed low hardness compared to steel heat treat for optimal knife use, I have found they are still more than capable of making a useful knife that holds a good edge. And grinding steel of any hardness is not a problem for the existing heat treatment and temper, as long as one uses appropriate heat management, the most basic method of course being "grind, dip, grind, dip, etc."

When I first started knife making, it was with pre-made blanks, and eventually a friend turned me onto making my own out of sawmill steel. I made a good dozen or so that way without heat treating, and I found that they not only were able to take extremely sharp edges, but they held their cutting ability surprisingly well for most EDC tasks like cutting cardboard, paper, packages, string, food, etc.

The problems that unheat treated sawmill blade steel present are that while their edges are not liable to chipping like harder blades are, they do have a greater propensity to roll if used for cutting hard media, and if ground too thin, their tips will bend much more easily than a knife hardened to a higher RC.

I eventually started heat treating them, and then moved on to other steels (1084, AEB-L), but when it comes to affordably making a knife for moderate use, my experience is that sawmill steel is a great way to go because even without heat treatment it can be ground quite thin for slicing, takes an extremely sharp edge far surpassing harder steels with large carbides, and is very easy to sharpen. Sawmill steel will work "as is" just fine for affordable kitchen cutlery, self defense tools, and EDC not intended for hard use tasks - as long as the customer is informed. I even made myself a couple machetes from "as is" sawmill steel, and they demolished everything I threw them at in the woods of Southern Ontario, in any given season - which even included hard chops into dead wood (the geometry on that machete was pretty thick though).

All that being said, I have for the most part moved beyond using sawmill blades steel, although I do still get requests time and again from people who like the romantic notion of owning a knife made from repurposed tools.
 
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