L-6 ?, How to Proceed?

[MSWallace]

Hi all. This is my first post over here, although I've enjoyed lurking. I've been enjoying making kit knives and Scandi style knives (with purchased blades) for a couple of years but have never attempted to make a blade on my own. Last week I reconnected with an Uncle I haven't seen for years, even though he lives less than two hours from me. We got to talking about my knife projects and he offered up some old steel he has in the shop and the use of his plasma cutter to blank out some blades.

Now, I don't know if this is even a viable option, so you're input is welcome. The steel is from an old lumber mill band saw. My Uncle got it from one of the many closed down mills up the coast from us (Northern California). The steel is in 12" wide sections about 5'-6' long and .092 thick. He probably has eight or ten of these sections sitting in his shop. Someone suggested to me that the steel might be L-6, my Uncle didn't seem to know, but thought that it would make good knives.

He says that if I make a blade template out of 1/8" sheet steel he can cut out blades using the plasma cutter. The cutter is mechanized to follow a template, not freehand cutting.

Does the plasma cutter compromise the temper? Can I grind beyond the blue area and avoid re-tempering? Here's a photo of the scrap he cut for me, you can see the area effected from the heat.

What do you think? Is this a crazy idea? It's appealing to me because I could continue to make my hobby knives while spending less on the ready made "kit" blades.

Thanks in advance for your input.
Mike

[mete]

It might be almost anything !! Probably not L-6. Yes the plasma will change the HT along the edge. You then have to remove the heated area by grinding. Hard to tell the performance though. Probably better for a chopper like 5160.

[ranger1]

Just my thoughts.
After grinding You will have to heat treat. Not knowing the steel will make this a guessing process, at best.
If you know the steel type, you can cut it out with the plasma, anneal, grind to shape, reanneal and heattreat and temper.
1- Mystery steel-----BAD
2- Known good steel------Good.

[Ray Rogers]

Let's look at what you're really saving here:

First, the steel is free and that's good. The bad part is we don't know what it is. However, we do know it was intended for use on saw blades so the heat treatment it currently has is likely softer than we would prefer for a knife. The heat treatment could be re-done but that would take some work considering we don't know what we're working with.

Second, the blades get blanked out for free. Again, that's good but the outer edges are burned and you'll want to grind that away. That will be a little more difficult to do because the steel is already hardened and the plasma probably made the edges of the steel even harder.

Now, let's look at the alternative. Buy a piece of known blade steel from any knife supply house or a steel supplier like Keyy Cupples. For $25 you'll get enough steel to make quite a few blades, you'll know exactly what it is and how to heat treat it. The steel will be fully annealed when you get it so cutting a blade blade out with a hack saw will take only minutes. The profile can then be cleaned up with files, belt sander, or even an angle grinder whatever you have. Chances are that with a little practice you'll be able to produce a blade blank in about 15 minutes.

From that point, all you need to do is file or grind bevels on the blade and heat treat it. You should heat treat the saw mill steel anyway so having to heat treat the steel isn't really a big step back. In the end, you'll have a much better blade. To do the heat treat, you can build a small gas forge. It takes about a day to build one and can be done without welding although I bet your uncle could do that for you too. Total cost can easily be under $100 even including the gas regulator.

Bottom line: playing with the saw mill steel really doesn't save you much in money, time, or effort. It's just as easy to make good knives as it is mediocre knives...

[wineland]

I had a friend give me a section of a bandsaw blade that sounded like this one and when I checked it only the outer few inches were hard and the middle was soft. I could not get the middle 8 inches to harden well enough for a knife. Just my two cents.

Richard


www.winelandknives.com

[Woodchuck Forge]

If you are willing to do some HT testing you may have some good steel. If you take a piece of your steel, heat it to just above non-magnetic quench in warm oil and see if you can break it. Wear SAFETY GLASSES. if it breaks clean you might be able to make a serviceable knife out of it. .092 is a bit on the thin side but a scandi style can be done. I have quite a bit of band saw steel and it works out to be 15N20 or similar material. But this is not always the case so testing is a must. It is much easier to use known materials. This way you can use manufacturers process to start with your HT.

[MSWallace]

Thank you all for the comments. I can see the wisdom in starting with a known steel, as you have all stated. Until my Uncle offered up this steel to me I hadn't really been interested in making my own blades. From what Ray said, I might be able to get set up fairly cheaply. Good info, thanks. I have a copy of Wayne Goddard's $50 Knife Shop, haven't read it though, guess I should.

Another comment on the Mystery Steel that I didn't mention before, may not matter....
The bandsaw blade has carbide teeth attached on both sides of the blade. Looks like they could send the log through the blade in both directions.

I just put the scrap I have in my vise, 2" in the in the vise, 10" sticking up. I bent the scrap over to approx. 100 degrees and it didn't break. When I let go it returned most of the way, but was a little bent. I was able to straighten it back up. Does this tell us anything?

Thanks again for your comments,
Mike

[chiger]

Hey Mike,

Not sure it really tells you anything important about it other than it is springy. ;~)

I've got some of the same sort of thing from a sawmill where I use to grade lumber. When they'd wreck them they'd cut 'um up and I got some. FREE STEEL...COOL! Makes great kitchen knives. I've made several. Not real hard if you don't heat treat it. Just guessing at probably 40 Rockwell C or so, so it won't hold an edge very well. Sharpens easily though.

Most band mill saws are made of some sort of spring grade steel. Especially the older ones, but there are cheap ones just like anything. The fact that it's a double cut band mill blade tells me it's probably made of better steel. Those things have to be strung really tight in order not to be run off the wheels. I've seen them throw pieces bigger than the piece in your pic through a steel exterior wall 150' away when a sawyer screwed up.

Just do a simple test. Heat up part of it with a torch till it's red hot and dunk it in a bucket of water. Even a propane torch should heat a small section. That will make it as hard as it can get. If the spring goes away and it snaps when you bend it or it cracks when you quench it, it will heat treat with oil for sure.

I don't blame you for wanting to get your uncle involved. To me, doing stuff like this is what I love about knife making. Doing stuff in a different way. Or redneck engineering in other words. ;~)

Good luck. Try the test and let us know what happens.

chiger,

[Ray Rogers]

On a circular saw blade - which I know you don't have - having carbide teeth added to a mild steel center is a way to make cheap steel cut better and a way to make blades cheaper. If what Chiger said about a Rc 40 is correct then I'd say this may also be the case with your saw blades. That means they'd basically be a waste of time compared to real blade steel.

The $50 Knife Shop book is a great place to start. If you need more help will building a forge than it provides, just post your question. I love building super cheap forges and burners. It's amazing just how cheap and flimsy they can be built and still work just fine .......

[chiger]

Ray's right about that forge stuff Mike.

I think I've got less than 30 bucks in my charcoal forge. Used some re purposed stuff (JUNK) from around the house, bought a bag of play sand, a dimmer switch and some fire brick. It'll do the job.

You already own the book, might as well read it. Ray's right. We hear from guys all the time that need something clarified from the book. It's a good place to start.

Oh, Ray...with these big band mills, I think the carbide is because it last longer and can be replaced if it gets knocked off.

The saw filer at the place I got my steel told me that the 30' bands cost form 6500 to 12,000 bucks. That's a big difference in price. Quality too I would imagine.

You are right though. Mike should buy a sheet of a know steel and let his uncle use his cool machine to cut out his blanks for him. If I were him, I'd use the band saw mystery steel for playing and experimenting with.

As I said, they make good custom fitted kitchen knives that earned me some serious points with the wife! ;~)

chiger,

[MSWallace]

Again, I appreciate the input from you all. I like your idea, chiger, of just experimenting with the stuff. My Uncle seems more excited about seeing it put to use than I am. At this point, if I was to tell him I'm not interested in using his steel and showed up with something else...., well, let's just say I'm not seeing that as an option, yet.

I don't want to come off as disregarding the great advice you guys have given me. I look forward to the making my own blades in the near future, I just see the need to proceed with this option for now.

OK, now thats out of the way...... I took my propane torch, with MAPP gas, and heated up the center of the scrap till it was glowing good. Probably a couple of minutes. Dunked it in a bucket of water, nothing happened. Put it back in the vice, bent it, and it snapped before I'd bent it 5-10 degrees. Here's a pic of the break..... does this tell us anything?

[Ray Rogers]

Good information, Chiger. Even though those blades clearly are not 'cheap' at those prices and the carbide tips are there for good reason, their presence tends to support my conclusion about the steel in the rest of the blade. After all, the tips are where the cutting gets done so why spend a lot of money on the rest of the steel if it isn't necessary? The answer is, of course, that they wouldn't . A mid range steel similar to 1035 or maybe 1060 would be more likely for the body of the blade. Such steel could get into the Rc 40 range as you imagined but wouldn't get hard enough to make what we would consider to be a proper blade.

As for forges, I made a couple of gas forges out of thin sheet metal, Inswool, and a couple of bucks worth of pipe from the local hardware store. One of them even uses a battery powered blower and would fit in a suitcase. Tai Goo made one from a coffee can, some wool, and a Harbor Freight weed burner. Every one of these contraptions will get steel to welding temps .....

[Pete Parsons]

Mike,

I agree with all these guys that are saying buy/use known steel...

If you want to be sure about your steel, have it tested. Someone hop in and give us the name of a place that will test a sample of Mike's steel.

Short of having it analyzed, continue the testing you have started. The fact that you can harden the steel (that's why it broke), tells us there is significant carbon present. Now we need to know how hard the steel will get.

Try filing the hard section of the broken scrap. Can you mark it or does the file "skate" off the steel? If you can't score the steel, then the steel is harder than the file and will make a servicable blade.

I believe (someone correct me if I am wrong) the plasma cutting will not affect the finished product assuming you have the tools to grind hardenerd steel or you anneal (soften) the blanks prior to grinding. This annealing would require a forge like Ray and the others have mentioned. Regardless you are going to need to have your ground blanks heat treated to get them to hold an edge. You can have them sent out or build a forge and do it yourself. Lots of info for both options here in the forums.

I have a friend knifemaker that gets great joy in scrounging steel for free even though I have offered him access to to my stockpile. It's what he enjoys and so be it.

Personally I feel making your own blanks (compared to using kits) is a step in the right direction and will increase the satisfaction you get from knifemaking. As long as the steel is good, use it.

Welcome...it sounds like you have been bitten by the bug. Enjoy!

Pete Parsons

[Mike Turner]

I am in So. Oregon and all the big bandsaw blades here are 15N20. Here are 2 I have that are waiting to be cut up,

[Ray Rogers]

Mike,

Your picture might tell us something, but it's difficult to say exactly what that might be. It appears that the grain size is fairly large and coarse. That could be because the steel is crap and not suitable for knives or it could just be because you made no attempt at controlling the temperature before you quenched.

Try again with a smaller piece, about 1/2" wide and 2" long (sometimes referred to as a 'coupon'). Heat it carefully and slowly just to the point where a magnet is not attracted to it (don't heat the magnet with the steel!). As soon as the magnet loses interest in the steel quench the piece in warm oil. Used motor oil, hydraulic fluid, old oil from a deep fryer - most any oil will do for now as long as it's warm (about 125 F). You can warm the oil by quenching pieces of hot scrap steel . Let the steel cool in the oil until it's comfortable to touch. Then try the file test mentioned above to see if it skates, afterwards break it (eye protection!) and look for a fine grain. It should require some effort to break even this little piece.

If the steel doesn't seem up to par for knives, console your uncle with the thought that you can use it in damascus later when your forge is looking for things to do. Even if it's not prime blade steel it seems good enough that it might do OK when mixed with some other good steels. Normally, I wouldn't suggest this solution but it could keep your uncle happy while producing a blade that is at least moderately high quality....