Hi Jeremy

To answer your question in the title of your post, No you do not need an oven. The number of excellent performing knives made without an oven would be quite impressive. I myself did my JS test knife hardening the 5160 blade with a torch.

Since then, I came across a great deal on an electric furnace and have used it every since. The main advantage of using a furnace is you can get consistant, repeatable, and predictable results.

Like many people, I have aquired tools as time has gone by. put a furnace on your list, but don't think that it is a must have, a torch in a dark room can be very effective too.

Brian

Jeremy, it would all depend on how you yourself are geared. Different folks have different goals, for some it is the best using knife according to their experience and comparisons, for others it may be just good enough to do X, Y and Z and that is “good enough”, and yet for others it is every last percentage of performance properties they can possibly squeeze out of the steel, but those properties can change from person to person. For some toughness is tops, for others strength is critical, some will put an emphasis on edge holding over ductility, others will want a blade that will bend endlessly rather than break. I could go on and on and that is the pit-fall of defining this area of our craft, and why there seems to be so much disagreement, we all have our own definitions.

The reason I took the extreme science based approach I took was to try to somehow get above all the subjective and personal views in order to see if I could see some solid landmarks in the chaos. Under microscopes and lab type testing equipment the steel doesn’t give a rip about our personal tastes it just reveals what it is in black and white. The problem is that a blade with microscopic issues may not manifest the same issues on the macroscopic scale. Such a blade my cut less rope but a human would get too tired of cutting rope to find out. This brings us back to the subjective world of human experience vs. the black and white objective facts of the steel.

Thus it is safe, honest, and accurate for anybody to say that without soak and temperature controls it is entirely possible to make a knife that will meet all personal expectations. But the neurotics like me who obsess over the microscopic details, and the last untapped percentages in the steel, work on a different paradigm. I don’t say that anybody isn’t making the best knife they can according to their own needs and desires, I can’t do that because I can’t tell anybody what their expectations are. But I have encountered a rare few who presented some of their opinions as if they were fact, despite how much the real facts would beg to disagree, and that drove me farther along my path.

Take two blades; both made of 52100, heat treat one with a controlled oven and one with a torch. Some would say that the torched one lived up to all their expectations, and that is correct, honest and accurate. But some would say that there is no difference at all between the two knives or even take their opinion beyond that as if it were fact, but the steel and the facts would beg to differ with them, as would I since I always feel best siding with the facts.

Now all that I have been going on about is also very dependent on the complexity of the steel. The simpler the steel, the simpler the tools that you can use to unlock most of its potential, thus 10XX and W series have been a favorite for guys with forges for a very long and for good reason. But take something like O1, which had no equivalent in the ancient world before controlled ovens, and eliminate the soak and tight temperature controls and the differences will become more apparent in the end product. Once again, if simply cutting a certain number of ropes is the goal then perhaps not as noticeable, but when accurately testing specific properties of the steel the differences are obvious, and would manifest themselves over much larger and longer uses. No knife will ever see the wear that an industrial cutter or slitter will see, but industry designs the steel and its treatments to meet that challenge, as hand tool makers and users we have the luxury of not having to notice the difference.

So after a whole page of my blah, blah, blah… It is still all about our goals and how far we take them, and with what steels, but just to make a decent knife just about any method or tools will get the job done, as is evident by the number of fine knives that have been produced by various methods over the years. I would say first make a good knife and then decide how far you want to push the envelope, before filling your shop with expensive gadgets. But also remember that no gadget can replace knowledge and learned skills. With them our tools become most pwerful but without them, gadgets can be a liability.

Thank you both for your thoughts and I agree with each of you that good knives can be made without all kinds of tools. Mr. Cashen, you also make some very good points on what exactly the expectations are for a given knife. I wouldn't consider myself quite "neurotic" (though I greatly appreciate your passion), but I definitely have a bit of the mentality of getting everything feasible out of a given blade. Of course, I'm new enough that it's entirely possible I'll get to a point within my making and testing where I feel I've reached "good enough" for practical purposes and use. You also make the valuable point that tools or machines can't replace knowledge or skill. Starting out draw filing before ever getting in front of a belt grinder taught me many lessons that will serve me well in several ways for as long as I make knives.

Thanks again for your thoughts.

Jeremy

Jeremy, I got so carried away with my discourse on the philosophy of equipment that I actually sort of overlooked some of your questions. I am sorry for that; allow me to now address them if I may.

Any steel will benefit from some degree of soak before the quench; just some will not suffer from its absence as much as others. The simpler the steel, the fewer requirements in soak time. Electric ovens are pretty good at this but are not perfect, unless special designs are used to control atmospheres, the open air of an oven will result in perhaps problem levels of decarburization or oxidation (scaling), and the longer the steel is held at temperature the more pronounced these problems can become. So with and oven, an investment in anti-scale, foil wrap or some other means to protect the blade surface would be a good idea.

On the other hand, forges have a rather controllable atmosphere and can eliminate oxidation quite well when used carefully, but they need much more effort to obtain tight temperature controls. I have seen very impressive precision in temperature from gas forges that can be throttled down and monitored with a thermocouple. Here evenness of heating is the only issue left to overcome and this can be done with careful forge design. I personally am very partial to the horizontal cylindrical design for a nice even heat when the work is placed down the center of the flames vortex, but others have gotten very nice results by going with larger internal dimensions and a low steady flame.

About the toughest to hold an accurate temp for any time in would be the coal forge, but even this can be used in a pinch if you get creative. I prefer to coke down a nice clean deep fire and then build a narrow firebrick tunnel over it to contain the heat and atmosphere. If this is done correctly you will get a beautiful carbon rich flame coming out of both ends that will keep your steel very clean. You can now heat the blade spine down in the fire and slowly bring things up to a very even temperature, and if you are really good you can even hold it there for a little while by continually moving it, but overheating can occur in the blink of an eye. All that being said, if I have a simple steel, I actually prefer using the coal forge with a brick tunnel over a gas forge when I do demos ways from home.

Kevin Cashen:

"Any steel will benefit from some degree of soak before the quench; just some will not suffer from its absence as much as others. The simpler the steel, the fewer requirements in soak time. Electric ovens are pretty good at this but are not perfect, unless special designs are used to control atmospheres, the open air of an oven will result in perhaps problem levels of decarburization or oxidation (scaling), and the longer the steel is held at temperature the more pronounced these problems can become. So with and oven, an investment in anti-scale, foil wrap or some other means to protect the blade surface would be a good idea."

Mr. Cashen, I am using a laboratory muffle furnace (only +/- 2 C with internal variation of about 5 - so its a cheapie and the control isn't that tight, especially at 1000 C) for an oven on small blades and heard about anti-scale. I just got a can of antiscale and was wondering if you can still edge quench with it. I would imagine yes, as it's a real thin coating, but figured I'd ask. Also how does this stuff affect the oil? I mean my peanut oil is cheap at the local Chinese supermarket but the Parks 50 stuff isn't...

Thanks again.

|quoted:

Kevin Cashen:

"Any steel will benefit from some degree of soak before the quench; just some will not suffer from its absence as much as others. The simpler the steel, the fewer requirements in soak time. Electric ovens are pretty good at this but are not perfect, unless special designs are used to control atmospheres, the open air of an oven will result in perhaps problem levels of decarburization or oxidation (scaling), and the longer the steel is held at temperature the more pronounced these problems can become. So with and oven, an investment in anti-scale, foil wrap or some other means to protect the blade surface would be a good idea."

Mr. Cashen, I am using a laboratory muffle furnace (only +/- 2 C with internal variation of about 5 - so its a cheapie and the control isn't that tight, especially at 1000 C) for an oven on small blades and heard about anti-scale. I just got a can of antiscale and was wondering if you can still edge quench with it. I would imagine yes, as it's a real thin coating, but figured I'd ask. Also how does this stuff affect the oil? I mean my peanut oil is cheap at the local Chinese supermarket but the Parks 50 stuff isn't...

Thanks again.

I am sure any number of very qualified smiths could also jump in here and provide excellent advice, particularly on the edge quenching aspects, which I would have less experience with than many others. I don't believe the anti-scale should have any effect on that method. As for the impact it may have on the oil, it will be quite similar to high temp salts if it should come off from the blade, i.e. you Will eventually get a buildup of particles in the bottom of the quench tank that you can drain the oil off the top of periodically in order to clean things. The material itself will most likely have less solubility in the oil than salts would and I have experienced very little effect from them.

Kevin

The anti scale that I use from Brownells comes off in the quench and drops to the bottom of the tank as a solid. I have done edge quench in the past and the antiscale comes off at the quench level. The remainder of the antiscale has to be removed from the blade. Hot water takes off the anti scale I use.

I don't use edge quench any more as I have adopted other methods, and the last time I did it, I was using Parks 50 and it caught on fire and was difficult to put out, so be careful.

Brian