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I Forge Iron

Saw blades


billp

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If they are a blade with carbide welded to the tips of the teeth the body is medium carbon at best, but is good metal for many uses all the same. If the blade is made from a single piece of metal you are likely holding good knife making metal.

Either way make test samples because it is mystery metal and you need to know how to heat treat it before you can use it.

Phil

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Some have carbide tips and others do not the older blades are the solid ones and a few have a diamond in the center for the shaft hole if that means anything.
What kind of test do I need to use to see?
Sorry for all the questions but I'm new to making knifes and trying to learn.
billp

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The spark test is probably the one you want to use to check out your saw blades. First get a piece of mild steeel and a piece of tool steel, run them across a grinding wheel paying particular attention to the spark formation of each type of steel. Then do the same with a scrap piece of one of your saw blades. Which ever saw blade makes sparks like the tool steel is the best for making knives.

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The diamond has to do with the arbor size that the blade ran on. It doesn't mean anything about materials used, unless it is an obvious knockout, which will mean the metal is softer.

The blades that are obviously made from one material are you best bet. Compare a spark test near the center with a test near the tips, just to make sure.

My Dad has a rather old dado set that I machined out to fit his table saw...incredibly hard material. The lab aid and I spent weeks figuring out how to do the job without breaking the tool and ended up using a solid carbide center drill for setting up a part on a lathe. (A prof borrowed the tool special for the job from a local business) That blade set has been resharpened at least once since I did this.

Phil

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OK I am working on putting the scales on a type of skinnig knife I dreamed up from an old 10" table saw blade about 1/16" thick. When I went to drill it out for the brass pins I almost could not. In fact I think I burned up one bit just to get two holes. It was a solid blade that is older then I can remember.
Does this mean I got a good piece to make my knifes from?

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OK I am working on putting the scales on a type of skinnig knife I dreamed up from an old 10" table saw blade about 1/16" thick. When I went to drill it out for the brass pins I almost could not. In fact I think I burned up one bit just to get two holes. It was a solid blade that is older then I can remember.
Does this mean I got a good piece to make my knifes from?


That is a safe bet.

The question is how do you heat treat it now? You need to know the temperature to harden from and the medium to quench in, then you need to know the temperature to temper to (at least the last one you can sneak up to instead of needing to know it outright)

Since you have extra material from the saw blade, make several pieces a similar profile to the knife blade (blank) and run heat treat tests on the pieces starting with air cool from non-magnetic and somewhat warmer than non-magnetic, test for hardness with a file and possible break them to check grain structure (use appropriate PPE). If the results are unacceptable then run oil quench from both temperatures, I doubt you will end up with a water quench (which would be next). Have a look at air hardening and oil hardening tool steel specifications to see good temperatures to try.

Once you work out a suitable process THEN heat treat the knife.

If you made a stock removal blade without overheating I would consider drawing the spine and tang while leaving the cutting edge alone (water bath while tempering) or see if a sample bends instead of breaking, and can hold an edge...if the sample performs suitably no need to heat treat if you didn't change the original heat treat of the blank.

Phil
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About the blades are about 25 to 40 years old. I have the bad habit of never throwing a blade away and kept them all which in this case is good. Only problem now is trying to find them as I have moved twice sense my first table saw. I might even have a few older then that if I check my Dad's box with has his old saw in it.

So should those work? I know the older blades I have I put in a vice and tried to break and would not just bent around but took some work to do so. One newer blade bent like butter so I took this to be a bad blade to use and the older ones better. Again am I right in thinking this?
Still learning.
billp

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I know the older blades I have I put in a vice and tried to break and would not just bent around but took some work to do so. One newer blade bent like butter so I took this to be a bad blade to use and the older ones better. Again am I right in thinking this?
Still learning.
billp


Ability to bend by itself does not mean anything to edge holding they are different functions. Most good blades will bend and not break, but your straight razor for shaving will not bend much. when it is a good blade, do you see my point? Dont confuse one thing with others. Edge holding, abrasion, and flexibility are different things and does not always mean that when one of these areas test high that the others will be also.

If you want to make a blade with them, go ahead. Grab a saw blade, Heat to just above non magnetic, quench in oil, and see how it is with a file test. If it is too soft, try again in a water quench.

When you want to get serious about making real knives, you will buy a known steel, they cost from $2.50 to $4.50 a pound on average, for non SS steels. Why spend many hours of your and our time trying to save 50 cents to maybe get a usable blade?
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I can take a blade you have great trouble trying to bend and make it dead soft. I can take a blade that is pretty soft and maybe able to make it extremely hard and brittle.

There are two aspects to this: Alloy and Heat Treat. If you take a wonderful alloy and do a poor heat treat for it then the blade will be junk. If you take a terrible alloy---well there may be no heat treat that will get it beyond "letter opener".

This is why testing of unknown steels becomes important if you want to make a blade from it and testing *before* you put a lot of work into it is strongly suggested.

You may want to look through "Step by Step Knifemaking" as it sounds like you are trying to use his techniques for blademaking. Your local public library should be able to ILL it for you.

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Most solid circular saw blades I've seen were a water hardening steel. The production line I saw had the blades coming out of the furnace on a conveyor, dropped it on the spindle in a quench press and the press would close. All automatic. The quench press had water cooled platens that held the blade perfectly flat while they were cooling. Very fast quench. Then they were drawn, the teeth set and sharpened. In this thin of a section, I'd expect them to be anything from 1045 to maybe a little better.

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Wow now it gets serious, I have been blacksmithing for a while now and have always wanted to try knife making but didn't cause I thought it would be more trouble then I would like. But I have always like knifes can't go by a sporting good place without wanting to buy one. So though I would give it a shot and make my own.

I understand about different alloys and how heat treating and the way you do it can make or brake metal, just don't know the chemistry of it all. Looks like I have a whole lot to learn and a ways to go before turning out a really good knife.

I did buy some high carbon steel for knife making which they also give you the stats on how to heat treat. I was just kicking around with the saw blades cause I had them. In fact it has helped me in develeping a technique in forming the knifes but it has also shown me I have a ways to go before I create a really good knife.

So I guess now I need to buy a book and look into chemistry of metal. I have been using hand gringers to form my blades if anyone has a suggestion on something else that want brake the bank I'm all ears or I should say eyes.

Thanks guys for all the help I'll get it down before to long
Thanks again
billp

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Bill nice to see you still have an interest and a desire to learn and grow..however make a few knives while you learn more about the technical data.
For starter pick up a made in usa used car coil spring. use a torch or a side grinder to cut off half or three fouirths of a coil, Cut several, Straighten it out hot and get a knife shape out of it. Heat it up to the point a magnet will not stick to it and memorize that color, Now heat to that color and let air cool three times. that will remove stresses from forging. Bring it back to the non magnetic color and dip straight down into the oil, I use tranny fluid,,atf. and heat the oil to about 100f. And be prepared for a flare up. If you stop for the magnet you will lose heat quite a bit that is why the second heat for color. Test with a file,,the blade should be real hard to remove any metal with a file. Have an oven ready at about 375f I use a toaster oven from a yard sale and have checked it with oven thermometor. Couple of bucks.for oven. Leave in for 45 minutes and remove with a tool ,,check with file again. if the file still skates and does not cut,,( a good file!) Back in oven for half hour and retest. Grinders, sand paper or wot ever you like to smooth all surfaces. Add ahandle and put an edge on and start testing.. If you have any problems along the way that seem real bad just chuck it and grab another piece of spring. This wll not make you a maker of fine kinves but just may allow you to get started and have a realy nice start. Start a log book of wot you used, wot you did and how it worked out. Will be a great reference later.

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Use a hand grinder to remove the scale and then draw file with a good file---surprisingly fast an leaves a much better finish than the grinder! Also get a file card and use it a lot!

There is a "Metallurgy for Knifemakers" by Verhoeven (sp?) out there on the web that is good.

You may want to look into the neo-tribal knifemaking which is a forge close to final form and finish using hand tools.

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I made a few knives out of scrap, but now that I'm trying to sell a few I use known steel only. I used automotive spring(5160) and ball bearings(52100) for my stuff. I always tested my material by cutting a 1/2"x1/2"x2" rectangle off and harden it. I would heat it to non mangetic then quench in my slack tub (water). Sometimes the steel will decarb on the outside a little so I grind it down clean (Caution do not over heat it). Then I see if a file will slide over it. If the steel passes thist test I then clamp 1" it in my vice and hit the other inch with a hammer (use safty gear glasses, gloves, ect). The steel should break and not bend. If your saw blade will not pass these two tests I would not use it for a knife. I don't think people here are trying to hurt your efforts only save you from making a mild steel knife. I use a lot of stuff from Mr Wayne Goddard's book "50$ knife shop"

I hope this helps, good luck

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I remember how amused I was the first time I ran into a low alloy strain hardened leafspring that would not harden when quenched. I mention this to people whenever I feel that they may get the idea that all leaf springs are a specific alloy---why testing each one is a *good* idea!

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  • 7 years later...

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