Saw blade knife

[Jd33]

Okay all , have cut my knife shape out of an old saw blade I found on site ( do hope no one wanted it ) and have read lots about hardening and annealing ... What in lay mans terms do I need to do next ,,,,,,
Can I just sharpen it and just face the fact that it won't hold an edge or will it be okay as it is .............,..,,,,

[saxonaxe]

Stand by Jd one of the forum forge wizards will be along soon..;)

[Adam Savage]

It depends what sort of saw blade it came from, as there are many different metals used in saw blades these days.
If you didn't harden it, it would (as you say) work as a knife, but keep loosing it's edge pretty quickly, and the edge would probably roll if you try and carve hard things with it, like hard woods, woods with knots in, dense grained woods, etc.

If it's a carbon tool steel, such as O1, o1040, or similar, it will be pretty easy to heat, quench, and temper. If it's HSS, Sandvik, or similar, it will need a slightly more complex heat treatment process, with more specific temperatures.

Hope this helps a little :)

[dave budd]

about to contradict some of what Adam has said now, sorry mate ;) Also to expand on his very accurate info! :)

Saws will be made from different types of steel,certainly. I've found circular saw blades made from HSS and weird air hardening stuff as well as plain carbon steels. Hand saws and bandsaws are medium to high carbon steels and most suited to reworking. Most hacksaws (power or hand) and a lot of metal cutting bandsaws are bimetal, that it HSS on one side and carbon steel on the other, not very helpful.

The type of carbon steel that a handsaw is ade from is going to be a medium carbon, fairly low alloy. Such as cs70 (1070 to the yanks), 15n20, L6, cs60, etc. O1 is not likely to be used since it is too pricey and too high alloy, 1040 (EN8) isn't likely to be used since it won't hold any kind of edge and is normally used for springs and large sections like hammers/anvils. Generally speaking, you won't know exactly what the alloy is, but assuming it isn't HSS you can just wing it and will be fine in this situation ;)

As it stands, assuming you mean a handsaw. If it is a newer saw with hardpoint teeth, then chances are the steel is good but the bulk of the blade will be failry soft temper (likely 48-52RC); so will blunt pretty quickly. If it is an older one, that was meant to be resharpened,then it will be a little harder (maybe up to 55) and will hold a slightly better edge. Either way, not what you are used to in modern knives.

Harden them at a red or orange and then temper in the oven starting at 190C and raise by 10C each time until you find a hardness you like. can't say how high to temper coz it could be from 190 to 230 depending on the alloy used ;)

[Jd33]

Thanks dave it is a circular saw blade if that helps

[Adam Savage]

Thanks Dave for the corrections :D I always thought 1040 would hold an edge. Goes to show how much I know lol

[ammo]

Love learning from you folks. I've only done two knives, I forged them cherry red, and temper at 200 degrees. The smell in the house, Wow.(didn't expect a smell) I'm scared to try again, the boss will kill me.

[headshot]

this is my little necker that was made from a blade from an old lumber saw,i had it made so cant help on the heat treatment but i will say its a fantastic blade,holds a razour edge for a long time and is a great little carving knife
http://i798.photobucket.com/albums/yy264/headshot_05/002-21.jpg (http://s798.photobucket.com/user/headshot_05/media/002-21.jpg.html)

http://i798.photobucket.com/albums/yy264/headshot_05/006-22.jpg (http://s798.photobucket.com/user/headshot_05/media/006-22.jpg.html)

atb kev

[dave budd]

I've had mixed success with circular saws. Mostly they are OK and are the same selection of spring steels as hand/band saws, but I've definitely had one that split in two when I quenched it in oil! It's probably best to cut a sliver off and try heat treating it before spending time making a knife ;)

1040 will hold an edge, just not for that long :D

[Adam Savage]

1040 will hold an edge, just not for that long :D

Ahh lol, maybe I was getting it confused with 1095, but then again, that could be totally different altogether :)

[dave budd]

1095 is very different to 1040 :D

10xx means that it is a low alloy carbon steel. The last two digits indicate the carbon content. So 1040 is plain carbon 0.4%C, 1080 is plain carbon at 0.8% carbon, 1095 is 0.95%, etc.

Then you get oddities in the 10XX range, where they are still a low alloy plain carbon steel (technically) but have some additives. Normally they are referred to as 'modified' such as 1084 modified is 0.8% carbon with a bit extra stuff (vanadium I think).

Of course the whole 10xx is an American designation and has not relevance to UK sourced steel :D The steel I buy is mostly EN of BS designation if British produced, or one of the various other naming systems used by the various European, Scandinavian and Japanese producers that make the steel I buy.

The more you learn about metals and metallurgy, the more confusing and the more there is to learn! Trust me, I'm reviewing a book on Archaeometallurgy at the moment and I swear I've forgotten most of what I knew on the subject!

[Adam Savage]

So is the US 1095 pretty much the same as O1, or are the other additives very different?

You've done a fantastic job of explaining how the 10xx system is basically organised.

[dave budd]

not the same. O1 is more highly alloyed and normally slightly lower carbon. The closest to 1095 in the UK is Cs90 or Cs100 (they are 0.9 and 1%) .

They have various steels that you will see referred to that we just don't have a direct equivalent to, such as W1, W2, 5160 and L6. We have steels that do the same things industrially and steels that are similar chemically, but none that are similar enough to say they are the same steel under different names.

Some there are direct equivs, such as 1060 is cs60, EN9 is 1050, EN8 is 1040, etc

[Adam Savage]

Ahhh. Top stuff Dave. Thanks for the info T^

[Jd33]

Thanks all for all the input but I am none the fricken wiser ..... Would I be able to get enought heat in a chimnea to harden the steel or will I have to build a forge .................

[dave budd]

you should be able to, yes. If you have to, you can always try pointing a hairdryer at the embers to raise the temperature a little. Get a magnet and touch it to the steel, when the magnet no longer sticks (bright red most likely), quench the blade in oil. It should then be hard enough that a file skates off it. If it turns out to be the air hardening stuff like I once found then it will likely crack instead of just hardening!

[Adam Savage]

I'm lead to believe, that if you raise the temperature of the oil a little (heard several temperatures from different people, so Dave may be able to help here ;) ), it will reduce the "shock" to the steel a little, and create a more even quenching/cooling effect. Might reduce the chances of cracking slightly, if it is an air hardening steel.
It might not make much difference at all, but it's normally a good idea to heat your quench oil slightly anyway.

[dave budd]

mostly right in both directions :)

warming water for quenching reduces the shock and therefore chance of cracking compared to cold water
warming oil increases the speed of the quench by making it less viscous and allowing heat to conduct away more swiftly.

The temperature you need to warm each to will vary according to the steel, the type of oil (or water), what you are trying to achieve (full hardness, slack quenching or a hamon) and how brave/stupid you are feeling on the day. Generally speaking, oil works best when it is a little too hot to put your finger in (so hot washing up water), but even tepid works better than cold. My heat treating oil (commercially designed and available stuff) specifies 40-90C as the effective range, I work towards the lower side of middle but I know somebody else who goes for the hotter end, we both have success :D

So as Adam says, heat it up a little first, just to thin it a get the oil moving easily. I either use a lump of steel heated in the forge and then plunged in to oil, or point a blowtorch at the tank for several minutes until warmed

[Whistle]

Thanks guys .... I just love these "techie threads" , so much information , I want to try it myself !!!

Shall heed the warning about using the oven though , sounds far too dangerous ha ha ha !!!

Cheers Whistle

[Jd33]

Just an update guys this is how it turned out 12068
Didn't heat treat it ,the edge is pretty good

[NorthernYeti]

ive had good sucsess with a few of my old plastering trowles ;) just sayin

[Valantine]

ive had good sucsess with a few of my old plastering trowles ;) just sayin

I never even considered using old building tools for blades - nice idea T^

[NorthernYeti]

i tend to have lots of warped ones nocking around