Triple this, Triple that... what gives?

Great point by Tia on the "cycles" and another great anology by Kevin. I also like the "simple test" demonstrating the grain size and hardening ability relationship.
 
Kevin R. Cashen said:
Also remember that in an oven it takes a good percentage of an hour just to bring the blade up to temperature and then only what’s left is used to actually temper, thus the 2 hour thing is a good idea. I do 1 hour or less in my first temperings because I am working with salts. I just saw an episode of “Good Eats” with Alton Brown that demonstrated this better than anything I have ever seen. He had a half dozen little ducky ice sculptures and tries to thaw them in several different mediums. One that was in the hot oven was not much more melted than one put in the refrigerator, while the one that was on cool water for the same amount of time was liquefied. This is the power of a liquid to conduct heat over that of air… insulator/conductor. Thus I must be careful not to pass along my tempering schedule times to folks with ovens and kilns or they will accomplish very little.

I have read, and experience has confirmed, that longer times at lower temperatures will give a better toughness at higher hardness, then shorter times at higher temperatures.
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I don't have a lab, but edge chipping tests, color of steel, and my file testing have led me to doing 2 hour tempering cycles as well. I'm really glad to have your confirmation of the health benefits of slow cooking :D
 
Oh my gosh! Tai is either on his meds or I am off mine since I am saying "amen!" to the majority of what he is posting here:D These are some real gems of wisdom:

Tai Goo said:
...I always think it's a good idea to get each step accomplished in as few heats as necessary to get it right.
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Amen!

Tai Goo said:
In the long run,... I think it takes some common sense and good judgment.

Speaking generally, it really all depends on what you want and how you want to do it under any given set of circumstances or parameters... It depends what you are making. For example with flint strikers and striking surfaces on striker knives, I actually grow the gain and leave it dead hard so it chips out easier and throws off a larger spark.
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I like that idea for the striker:thumbup:

Tai Goo said:
Another thing is that heat treating is an integral part of hot forging. In other words the steel is “heated”, primarily to soften it and make it more malleable under the hammer. However, the heating and cooling used during the overall forging cycles may be simultaneously used for other thermal advantages…
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Bladesmiths would be in a pretty good position with their products and beliefs if they would remember this point. Forget about the hammer and remember that you are heat treating during the forging process as well. If done correctly, i.e real good and hot in the beginning and slightly cooler as you progress and we may actually be able to improve the steel a itty bitty bit from how it came from the mill (much of the low temperature hocus pocus can make it worse). A very old fantasy of bladesmiths may be realized if we stick to common sense forging practices;).
 
Not to hijack the thread, but I was wondering if you, Kevin, could describe or post pictures of your low temp setup? I recently built and used for the first time my high temp salts, and I need to get some ideas for the low temp. Thanks!
 
... I think you are always better off doing as little as possible, killing two birds with one stone when ever you can, and trying not to jack the steel up too much. :)

If you want to find the best, easiest and most efficient way to do anything,... just hire a lazy person! :D
 
Phillip Patton said:
Not to hijack the thread, but I was wondering if you, Kevin, could describe or post pictures of your low temp setup? I recently built and used for the first time my high temp salts, and I need to get some ideas for the low temp. Thanks!
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To be honest I am not thrilled with my current low temp setup. I have doubled up my kilns and low temp tube in order to save space but I can't help but wonder if a low fired venturi setup with gas may not be more efficient. Most other people have had much better luck with salts and kilns, my luck has been abysmal and after suffering issues that nobody else has I am very keen on gas over electric for heating any kind of molten salts. I would strongly suggest the thinnest tube you can safely use for the low temp and line the burn chamber exclusively with reflective type materials (e.g. wool instead of solid refractory). Thermal mass is your friend with the high temp but your enemy with the low temp. When you put a blade into the high temp you want the salts to have enough thermal mass to simply absorb that introduction without a huge drop and subsequent rebound, this would be VERY nice with the low temp as well, but the trouble comes in when you want to bump the salts up 25 degrees for the next temper. If there is a large thermal mass involved in your tube or heating you then have to wait for the salts to catch up, overshoot, and then the controller will compensate and perhaps drop too low before rebounding with another overheat. These things sort themselves out at 1500F but at 400F it is much more sensitive.

I built a 2 foot tube for tempering that I scrapped because I used 1/4" tube instead of 1/8" and at 400F it was a heat sink that would not allow my setup to regulate the salt temperature.
 
Tai Goo said:
... If you want to find the best, easiest and most efficient way to do anything,... just hire a lazy person! :D
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That is not the first time I have heard that bit of sound wisdom, and while it may seem contradictory at first, think of how many advancements in efficiency were made by people with enough energy to continue breaking their back all day? And if you pay on a piece rate, one may come back to find that the lazy man you hired found a way to hire two energetic men with his original wages while he supervises the making of enough product to still collect a check for himself. Now you could get indignant, call him a cheat, and go on about fairness, or you could realize YOU just doubled you output as well with no extra cost and look the other way on your way to the bank.;)
 
Kevin R. Cashen said:
To be honest I am not thrilled with my current low temp setup. I have doubled up my kilns and low temp tube in order to save space but I can't help but wonder if a low fired venturi setup with gas may not be more efficient. Most other people have had much better luck with salts and kilns, my luck has been abysmal and after suffering issues that nobody else has I am very keen on gas over electric for heating any kind of molten salts. I would strongly suggest the thinnest tube you can safely use for the low temp and line the burn chamber exclusively with reflective type materials (e.g. wool instead of solid refractory). Thermal mass is your friend with the high temp but your enemy with the low temp. When you put a blade into the high temp you want the salts to have enough thermal mass to simply absorb that introduction without a huge drop and subsequent rebound, this would be VERY nice with the low temp as well, but the trouble comes in when you want to bump the salts up 25 degrees for the next temper. If there is a large thermal mass involved in your tube or heating you then have to wait for the salts to catch up, overshoot, and then the controller will compensate and perhaps drop too low before rebounding with another overheat. These things sort themselves out at 1500F but at 400F it is much more sensitive.

I built a 2 foot tube for tempering that I scrapped because I used 1/4" tube instead of 1/8" and at 400F it was a heat sink that would not allow my setup to regulate the salt temperature.
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Thanks, Kevin, I'll keep all that in mind. What are the dimensions of your low temp pot, and how many blades can you temper at once?
 
Kevin R. Cashen said:
That is not the first time I have heard that bit of sound wisdom, and while it may seem contradictory at first, think of how many advancements in efficiency were made by people with enough energy to continue breaking their back all day? And if you pay on a piece rate, one may come back to find that the lazy man you hired found a way to hire two energetic men with his original wages while he supervises the making of enough product to still collect a check for himself. Now you could get indignant, call him a cheat, and go on about fairness, or you could realize YOU just doubled you output as well with no extra cost and look the other way on your way to the bank.;)
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Sometimes lazy and smart are the same thing... kill two birds with one stone! LOL :D
 
Tai Goo said:
Sometimes lazy and smart are the same thing... kill two birds with one stone! LOL :D
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Those words of wizdom were Henry Fords, paraphrasing notwithstanding. Henry was the smart guy that hired the lazy guy that hired the two energetic guys...
 
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