O1 Tests -ideas?

southriv

southriv

Joined
Feb 28, 2002
Messages
751
I've been doing tests on O1 to see how well my efforts will perform. I've been making 5-6 blades at once, 3.5-4.25" in length, both hollow and flat grind. The first half dozen I made of 1/8" stock. I've been triple edge quenching in Brownell's quenching oil. They say to use it at romm temeperature, but it heats up about 120 or so after some use. I normalize the whole blade first, let it cool and then do the quenching. First lesson - I ground too thin and all but two warped when quenching. The remaining two (one hollow, one flat) I triple tempered at 400 for 1 hour. I did a quick sharpen - 60 to 400 to a quick pass on the buffing wheel. They would shave hair before and after 60+ cuts. So far-so good. Now the bending. The hollow ground edge cracked at about 60 degrees (no surprise-very thin) and the flat ground blade cracked just as it hit 90 degrees.

I'm well into doing another series in 5/32" leaving a much thicker edge before grinding. Then I will do the same tests. The last series will be with 3/16". Outside of thicker steel and less agressive grinding, the only other varibles I can think of is to temper at 450 for a lower Rockwell and maybe change the quenching medium.

Any ideas on where I should make some changes?I'd like to be able to cut and make the bend test, too. When I'm done with this I may post a page to show the process. All I can say is that I have learned more from all the mistakes of experimenting than anything else so far.

Enough for now - I'm taking the Harley out while I ruminate on this some more....

Bob

http://www.southrivermodelworks.com/page15a.html
 
Hi Bob-

I'm glad you're testing. Since I began forging I have been testing to destruction like crazy, and while it hurts a little ;) it has also built my confidence up a BUNCH.

A major thing to keep in mind on testing is that most knives are made specifically for a certain test. Such as the JS test. You can fly through that test with a long, distal tapered blade that's been differentially hardened, spine rounded over and a super sharp flat/convex grind. Take any of those characteristics out of the knife, and you make it that much harder to pass.

As far as bending blades: I have found that a thinly hollow ground blade will cut well, but will resist bending, so there's a major geometrical factor that will (IMveryHO) limit success for bending it. Also the shorter you get the harder it is to bend those blades down.

On hardness: Are you doing the brass rod test? This is a super easy and effective test. I have gone to doing that right after my last tempering cycle. I will take the blade out of the oven and put an edge on it and go right to the rod test. If you chip the edge, it's still a bit hard. Go up in small increments on your draw temp until it doesn't chip. If it kinks, it's too soft and should be cycled back through to re-harden. Also if you are using the kitchen oven be sure to get a small oven thermometer to double check the oven temp. Our fairly new oven wrongly displays the temp by about 10-15 degrees, but two little thermometers thrown in there agree (so just more insurance).

What is your heating source? It's hard to get an even heat on a blade prior to quench. About the only way to really do it and be confident you're dead on is with high temp salts or a heat-treat oven. It CAN be done in a forge or with a torch, but you have to be very careful to get an even heat.

I'm not sure that O1 improves with a triple quench. I haven't tested enough of it to say that for sure though. That's something else for you to try (one vs. three or 12 or :) ).

O1 is a neat steel. It's pretty forgiving on heat-treating, and if done right it will cut extremely well and be tough. I hope Little Hen pipes up here, I have seen some broken blades of his and he is getting a very fine grain structure and O1 is his dedicated steel.

Sorry for the rambling :o
Nick
 
Mike – just got back from my ride ( where I do some of my best thinking) and thought – "what about the brass rod test?". ….so it was good to see your post. I will definitely try that. I also think you are right on in a lot of your comments –after reading them it makes a lot of sense. From my readings, it does appear that the JS blades are specifiically constructed for that test. All of my shapes/grinds are definitely "challanged" by the bending test.

BTW, I am just doing stock removal at this time. My heat source is a torch with a rosebud tip. The heat appears to be pretty even, but then again , your observation on that factor plus the actual oven temp are definitely worth considering.

I do feel I have made some progress though, the blades cut like crazy and almost a 90 degree bend on a 4" flat ground isn’t that bad. Now, I think I’ll forgo the bending and go directly to the brass rod test.

Thanks for the input – rambling is OK!

Bob
 
I really like your post and will be checking it often. This is one I'll fire the printer up for.

I spoke by phone with Tim Zowada last evening and he set me straight on a lot of things concerning HT of O-1. Among them, he told me to look for the red to darken and ghostly dark spots or lines moving about the blade. When this occures, he told me, the steel is austanizing. Then the dark will dissapear. At that time, no longer than 15 seconds and sooner is better, quench immediately but only until the steel becomes about 400 F. (the oil on the blade should smoke but not flash). The quench is very short and the blade is moved in a direction in the oil as if to cut the oil. For my 8 1/2 blade it seemed like maybe 4 sec. give or take. Let the blade cool for about 15 min. before tempering. Tempering too soon, he told me, (I think this is how he put it) will cause the steel to Martinize too quickly and by letting it rest about 15 min. before tempeing increases blade toughness. Grind enough scale off a portion of the blade to be able to see the straw color while tempering.

Tempering times and temps for O-1 is something else I wish to discuss with him Monday evening during another scheduled phone call, but I'm guessing he'll advise on some temps and tell me to just look for the pretty straw color.
 
Rlinger .Thanks for the input. I’ve been doing pretty much as Tim recommends – I must admit more by chance than by design I’ve been doing almost exactly as you wrote. I’ll keep doing this as consistancy in methods while testing sets a baseline to go for change or discover mistakes.

Nick – I got your name wrong and called you Mike –sorry! I took the remains of my blades and did the brass rod test. I’m a little confused about what I am supposed to see. I have pressed the edge down on the brass rod at the sharpening angle and tried a up to a 30 degree angle. I’ve also drawn the blade across the rod using these angles. Wearing a magnifyer, when I press down I can see sometimes see a "dimple" in the edge about 2-3 thousands deep. When I run it across the rod under a lot of pressure (40-50 lbs I’m guessing –or more) It looks like the edge is rolling over. Again about 2-3 thou and I can only see this under magnification. It doesn’ t feel like anything when I run my finger across. However, this stays in the edge. I think might not have this process right…?


Bob
 
No problem, the guys on paltalk call me whatever they feel like...:)

When I do the brass rod test I first look at what the edge is doing. I like to see it swell over the rod, and then go back down to its original position after taking it off the rod.

If it does that, then I do it again at near the ricasso, and run the entire cutting edge over the rod at that angle in a long sweeping pass (like sharpening it). You want to watch that ripple where the rod is move down the cutting edge, yet have the entire edge go back to its original position afterward.

That's what I look for anyway, and a few different master-smiths showed me that...so feel pretty confident with it.

If your edge is rolling and it stays that way, the temper was most likely a bit hot.

Rlinger, I respect Tim a lot, thanks for adding his advice on here.

Good luck!
Nick
 
.... I salvaged three of my 1/8" test blades, reground them and heat treated them. I tempered all at 375 for one hour in my oven . At Nick's suggestion. I got an oven thermometer and also lowered my temp. (from 410). Anyway, I got a very light straw color - the color was just coming up. At 420 I got a noticably darker straw color.

I put an edge on one blade and it cuts well and seems to flex and return with the brass rod test. (I put a lot of light on there and got down at eye level so I could seeit ) I put the other two blades in the freezer and I am going to temper them again at 375 tomorrow -see what (if any) difference.

I don't know the answers yet, but after looking at the way my results are going and reading other threads and replies its looking like 350-400 is the best range, check your temp, temper an hour at a time and maybe more than once. Everyone seems to get a method that works best for them.

Bob
 
Nick,

You bet! I'm planned to call Tim again this Monday evening. Anything he says that I think pertains to this subject I'll be sure to report.

I'd like to go up to Mich. and see his shop. With all these ovens I'm planning on buying though I guess I better hitch-hike.
 
Hi Bob
 I see you posted it as you said you would
  I can't add much more then that has been posted other then
 I use a water tube to
.draw down the spine keeping the edge cold after
 hardening and tempering the edge,
 you can use the brass rod to check if the edge is right too. 
 also when they do the bend test it's done
on a big blade plus the 
 vice jaws are padded with wood so you don't get a sharp
 corner at the jaw.
  the ABS tests are in place so everyone knows
 you know how to manipulate steel once you've past the test.
 this does not mean that you have to use the same procedure
 on all knives, just that you can if you have to
 depending on the knife your making and what it's for.

  You have found out that yes you need more steel
 thickness on the high carbon steels.you found out the hard
way but it's a learned one.
 I use vegetable oil at about 130 deg. for the quench on O1
 in quench tubes I made.
(now this is just my opinion)
 when you edge quench your hardening more than
you need to on small blades and this may be causing
 your spine breakage on the bend test.
 with the water tube I have full control of what and how much
 I want tempered leaving the edge just where I put it.
 I replied to your email too.hope this helps.
 
Hey Dan -Thanks for the input. This certainly has been the learning experience I've wanted it to be. I thought that since I am going to depend on this steel a lot. I better learn its limits as applied to my own work.

I'm actually not that displeased with the results so far. I've been carefully edge quenching, but I am going to try your method, too.
At the beginning of this experiment, the cracking appeared only at the end of the bend and only into the edge - the spines always held up. I just "sacrificed" a 5/32" blade and it almost made it. Given the many issues with form & function & the JS test, I'm going to give the bending test a rest for now, though I'm getting a better idea of what does better. Like you said, however, it all depends what you want the blade to do.

I straightened all the test blades, reground each one into a semblance of a usable knife, edge quenched again and went on to tempering and brass rod tests. Per Nick's suggestion, I got two oven thermometers (different brands) and found my oven is spot on. I've been varying 1 hour tempering cycles by 10 degrees from 350 on and doing single draws, multiple draws and freezer "cryo". I haven't finished yet, but I have found that 10 degree increments do make for just noticable color changes between increments and subtle changes in performance and brass rod test results.

As a using test, I've done the rope, the hair the wood and I just carry the blades around and cut anything I can find, including a tough piece of meat I had for supper.....

Thanks, Bob
 
I noticed that you use Brownells tempering oil. I also use Brownells tempering oil and have found it to work very well. The directions that come with the oil say to use it cold. I have found that for knife blades it works better if you get it at least 120 degrees F before you quench in it. Also, if you pay attention to the temperature of your quenching oil, you will avoid one more variable which can effect your results. I passed my JS test with 5168 quenched in heated Brownell tempering oil. Tom Lewis
 
rlinger
do you mean the hardening session?:confused:
and maybe mean coating the complete blade
with the edge being thinner coated?
I 'm not sure what your up to with the clay
in the tempering draw down stage in the oven?
 
Haven't tried the clay - sounds like something for when I'm much more "advanced". I was a potter about a quarter century agoa, so clay does interest me, though I think instead I'll apply my kiln-building skills to constructing a forge..............

Bob
 
I mean the tempering session however, I could have it backwards (use your judgement based on experience - It has been a number of years since I was told this). Once back in the 80's a fellow (a very sientific fellow friend and co-worker of mine) was telling me of a PBS show or series that tryed to describe the way the old Jap sword makers made their blades. He described to me, with great enthusiasiam, that those old masters used clay (and various grades of clay for different parts of the sword) to insulate the tempering heat from the steel. in this way, he explained, they could control toughness and brittleness throughout the blade.

I have the clay to try this with. However, I am just now trying to learn to make my first knife and have chosen to go by advise found here and from tech sheets. I will be trying the clay wraped edge within a short while but first I need to learn how to do a simple HT and temper.
 
rlinger I believe
it should be as I mentioned, done in the hardening process.
( if your going to do it as the Japanese did it.)

 it could be confused with differential tempering
as most know it now.

the thicker rice ash and clay ( as they used)will keep
all parts, other than the edge, from hardening in the
water quench. it does insulate, but insulates
the cold of the quench from the spine so it
will not harden during the quench bringing it down show
past the critical temp so it won't harden,
the thinner clay would insulate it just enough
to harden but not crack the edge and leaving a hamon
(the temper line)
they also folded the high carbon steel shell
(that they also made from ore)
over a low or no carbon iron core
this process with the heating also
causes the curve in the blade.:cool:
but there is much to
the old masters ways, like content of carbon
in the steel they made and how the knew when to stop adding it,
the right color of the steel before the quench,
,, using polishing stones ecct.
 
Rlinger – The clay temper is an interesting process. I particularly like the visible temper lines. Like you, what I have read and heard applies to Japanense swords, though I remember some makers using the process for other projects. FYI, here is a site I found on clay tempering. http://www.sandiaforge.com/about.html. I know I saw some other infor, possibly in one of the annual knife books. On basic heat treat, I’ll give you some of the paths I followed. I’ve been making some notes and here are some of my thoughts after spending a weekend on this.

First, published reading. Wayne Goddards book, The Wonder of Knifemaking,, particularly Chapter 3, Heat Treating: The Real Secret to Blade performance is a definitive explanation of what does (and can ) happen and how to do it, You can also read a similar chapter in his other book, The $50.00 knife shop ( Chapter 4, Backyard Heat treating). Ed Fowler’s book, Knife Talk, particularly Chapter 4 : Forging and Heat Treating is a wealth of information. The article, How to heat Treat: The spirit of the forged blade, is a good one to read first. He gets in to the little nuances that can make a difference, like the settings and use of a torch. In these you are not given a Step A, Step B, etc approach to technique, but the benefit of all the sides trips one takes while experimenting and learning - just with the "simple" heat treat & temper.

The interenet. Also useful arethe late Bob Egnaths work, http://www.knives.com/engnath.htmlwork, and Don Foggs site http://www.dfoggknives.com/hardening.htm. Of course, you are aware of all the info here on the forums – Graymaker, who has been in this thread, is the ’01 guy’ up here. He has been doing the form & function bit with 01 for a long time. He helped me through my first heat treat – I’d listen to anything he has to say about 01.

Now, I’ve only been making for a few months. In that time I produced 5 completed knives. However, I felt that I had focused more on appearance than performance, so I switched priorities. What I’ve learned (IMHO) and what has helped me, is the more blades the better –especially with the learning/testing cycle. Granted, that first blade is a real hassle to get through – I went through the same thing. You want it to work, to be just right and yet you have nothing to compare it to – so that one blade becomes your entire focus.

I’ve profiled, ground, heat treated and tempered a dozen blades over the weekend. Appearance gains have been a side benefit here as all that grinding has taught me a few more things about that – but what I was really after was knowledge about heat treat-temper-performance. The multiple blades have taught me many thing: about my heat treating equipment, how I handle it, about consistancy in results, unexplained inconsistancies, puzzling out those inconsistancies, Murphy’s law, taking two steps forward and then one step back, etc, etc…. in short, I’ve gained a lot more confidence, but also have gained a lot more respect for the material which I’m working. I know now that steel, like any raw material, is fickle enough to keep you learning and guessing for a lifetime.

Following your efforts along side mine, I would buy a couple oven thermometers (cheaper than a new oven – its really helped me), heat your blade to non-magnetic, edge quench in 120-130 degree oil and temper for 1 hour at 375. Then sharpen and test your blade. Starting there, you have a baseline. You can do the same on other blades or start doing some variations and see what differences you get.

Anyway, just my questionable advice and certainly not an expert opinion….BTW . I really like what you do with gunstocks. AS one who like to experiment (also) with walnut & maple finishes I found your methods really interesting.

Bob
 
Dan, Thanks for that knowledge. My thinking, I suppose, is that the edge being coated with clay would decrease its tempering by a small number of degrees. I suppose the opposite should be if using it for the HT, in that other parts of the blade should be clay coated so to keep those sections cooler than the edge(???). What ever; I'm a little ways away yet from experimenting with clay coating.

Bob, thanks for the links, and the links, and the links. I'll check'em out - beginning with the last set first.

Yes, I gotta say that knowing what very little I do so far, I would advise anyone just starting to learn to properly HT and temper before designing, milling, drilling, filing, sanding, grinding, etc, etc. etc. a blade. Just order an extra bar of steel and grind a flat grind to about 20 - 25 mill edge and start HT'ing, tempering and testing. What think bout dat???
 
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