I've been watching this thread closely, but not saying anything because other folks are covering many of my thoughts better and more completely than I myself could. There are a few things that I would like to chime in with though.
First, I would like to take the time to thank Kevin, Mete, Fitzo, Stacy, Bruce Evans, Greg Obach, and everybody else who have worked hard to try and teach us all through providing information, insight, and results of their own testing. Not that I completely trust everything I read on the Internet, but when I can see an explanation of something from Kevin, or Mete in terms I can understand, and then I can compare that new knowledge to other sources, and verify the claims by working in my own shop, it certainly teaches me a lot, not least of which is a healthy respect for these men and their dedication. Oh, and I'd like to thank Tom Megow for even thinking of me in this discussion.
It's difficult for me to say whether I'm a newbie or not anymore. I know that I feel like a newbie more often than not, but after looking at Scott Ickes' recent poll I listed my self as an Apprentice. I feel that I've managed to get decent enough at some skills that I may be not just a newb anymore. Who knows? I do know that if I ever feel that I have nothing left to learn from you folks, that I'm well and truly done for.
Early on I worked with a decent amount of recycled materials, and frankly did not have great success. I realize now that a lot of that was due to my processes not being consistent or correct. I've recently begun working towards my JS and so I'm really testing some things now.
As a way to test my knowledge of process, I made a large test blade from an old spring harrow tooth a while back. All I knew of this steel was that it had been a spring harrow tooth of unknown, but old origin and that the gentleman who had used the harrow (who donated the teeth) had personally seen them go almost completely straight being caught on a root and then snap back to shape. In the interest of adding my $.02 to this thread, I'll relate from my experience rather than directly answer Kevin's questions. I think that I can provide more useful information this way. It's just a more effective method of communication for me. Here's how I did it:
- I forged the curved tooth into a flat bar
- I cut off a small piece, heated it to a bright orange and quenched in cold water. (This is useless other than I have found it is a reliable way to tell if something will harden at all.)
- I then clamped this piece in a vise and whacked it with a hammer. It snapped cleanly. Good sign #1.
- I then examined the fracture to see what the grain looked like after a violent quench from an overly high temp. If the grain hasn't grown terribly, I take this as a sign that the steel might contain some alloy to help retard grain growth such as Vanadium. Not terribly scientific, but we're not discussing pure science here... In this particular case, the grain was pretty large.
- At this point I forged out the blade. I knew I had something to work with, just wasn't certain exactly what it was.
- After forging, I brought the blade to a little above non-magnetic and allowed it to cool in still air. This was repeated for a total of 3 cycles. During this, I looked for (and found!) something very important. I was able to observe decalescence/recalescence. This is something that I'm surprised I haven't seen mentioned in this thread so far. The transition point was very obvious with this particular steel and I made certain to make a mental note of the color of the steel at the point of decalescence.
- I then heated the blade as evenly as possible to the color I made a note of before. Then I went just a TOUCH higher.
- I quenched in Parks #50. I used this oil for a few reasons. One, I had it available. Two, water had not caused the steel to ping before, so I knew a fast quench was a safe bet.
- File test time. Yes, I know this teaches us little, but it's a habit I picked up from my early teachers. It has told me on a few occasions when a quench did not work, so I keep doing it.
- I tempered initially at 400F, twice for 60 minutes each.
- I "blued" the tang, ricasso, and spine with a MAPP torch 3 times.
- Finished the blade out roughly. It was just a test knife, so I made it comfy, not good looking. I took it as an opportunity to test the quality of my standard hidden tang construction. The knife was assembled with no epoxy, only the pin to hold it all together.
I then proceeded to use this knife for everything around the yard. I hacked through trees and bushes that needed trimming rather than using a pruner. I observed the edge condition regularly, resharpened as necessary, and slightly reground the profile as I continued to learn about blade geometry. I hacked through 2x4s in the shop, I used it as a small spade to plant some mint in the yard, in rocky soil, etc, etc, etc. I learned something from every test. The handle loosened up a good bit, but the knife was still quite usable.
The last time I visited J. Neilson's shop, I figured it was about time to test this knife all the way. First, I made a few attempts at cutting a free hanging rope. From this, I learned that I need practice cutting rope
Had I had some more practice, I'm certain that I wouldn't have left that last piece hanging by a thread. Second, we grabbed a 4x4 hardwood barn beam and I proceeded to hack that to bits. It ALMOST shaved hair after that. I felt confident that had I been chopping 2x4s it still would have. Then we went to the vise. J. was just about to open his mouth to tell me I'd hit 90 degrees when the blade finally snapped. The rest of the blade only took about a 15 degree set.
Some might think I failed based on this story, but I see it as a grand success. On my first attempt, with an unknown steel, I ALMOST passed the standard ABS tests. This means to me that I understand the PROCESS well enough to make the best of things with an unknown steel. Am I more ready to take on testing with a known steel now? I sure think so.
Now, I'm not relating this story to try and say that the ABS test are the way and the light. The merits of these particular tests aren't up for discussion in this thread. They are however a benchmark I'm working towards and so I'm pleased with the results of my experiment.
Hopefully the explanation of my methods here will shed a little more light on how I deal with recycled steels. As a rule I don't use them in my work. I personally feel that if somebody is going to spend their hard earned money on my products, I owe them the best work I can possibly do, with the best materials I can provide. I'm not going to skimp on materials to make a few extra bucks off of somebody. That's just not how I operate. As a tool to teach myself process and rigor, they can be very valuable indeed.
So, there's my $.02 anyways...probably worth about $.01 nowadays, but hey, the economy sucks
-d
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I think the whole thing of strongly encouraging newbies to use known material is to save them the frustration many of us have experienced when "golly I done evrythin' right and it still don' work" 
Stacy, I cannot work out how to lock threads I started, perhaps I no longer have that privilege. But since I am not even a regular participant here any more I would be so happy if you would do the honors. I don't even think a eulogy is necessary before re-interring this thing, cremation would be nice but fossils wont burn.