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Author Topic: Thoughts on Knife Talk DVD volume I  (Read 11883 times)
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Ed Fowler
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« on: November 28, 2006, 09:29:49 AM »

As the new DVD gets into circulation, thoughts and questions are most welcome.

The first question that I wish to address concerns quenching the blade in Texaco Type A oil.
As explained in the DVD, the oil is preheated to 165 degrees.

When I quench the blade it appears that I am heating the spine with my torch. I am not heating the blade, but using the torch to burn off the fumes (smoke) in order that they don't fill the shop. Usually I have a filter that takes the fumes out of the air, it makes noise that would have interfered with our conversation, therfore I burned the fumes.

Actually burning the fumes is a beter solution that the filter, best is to burn them off as the form and use the filter also. I do not believe the fumes are harmful to the maker or I would not be alive today, but it does no harm preventing breathing them into our lungs.

Any of those who watch the DVD and have comments or questions, please post them here.    

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« Reply #1 on: December 09, 2006, 06:29:14 PM »

I just viewed the DVD. It's GREAT. What an eye opener. I've read a lot about knives and knifemaking, made some myself, gone to knife shows, and talked to collectors. But, seeing Ed in his element, demonstrating technique and discussing theory, puts it all in proper perspective. I'll tell you why. As we go through our lives we involve ourselves in various pursuits. There is always someone that does it best. And we strive to be as good as that person. Without that mental reference, we can't gauge our accomplishments or our shortcomings. I will never acheive what Ed has. Others will come close. But, we will all have the inspiration that he provides. So, I'll stir my rum with my latest knife and salute you Ed Fowler.?
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« Reply #2 on: December 10, 2006, 10:29:07 AM »

Thank you for the kind words, it means a lot to me when I am able to communicate what has been my obcession for the past 50 years or so.

While what we demonstrate in the video may seem a bit overwealming at first, I assure you that you can do it. Maybe not all, some parts of the process can be applied to stock removal blades as well as forged. The testing can be done on any blade. Testing leads the way, when we test we learn what we have and with a little luck how to make it better.

Every aspect of the information presented in the DVD is backed up by Rex and his lab work.

While some shortcuts may be appropriate, just remember Rex's comment. "The first time you get 90%, the second time 90% of the remaining 10% and the third pass is 90% of the remaining 10%.

Nothing happens fast, elbow grease and testing can lead to success. Each success we have enjoyed was preceded by numerous failures. Each failure left us with knowledge.

Don't be afraid to try the events you can do in your shop. If you have any questions, don't hesitate to post them here or simply call me. 

I do urge posting here also, that way we share information with more who are interested.
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« Reply #3 on: September 20, 2007, 07:01:01 AM »

Since we completed the DVD Rex has been able to add to the information presented in the presentation.

The three post forging quenches have proven to be extremely beneficial toward the finished blade. I sent Rex some samples:
#1, no post forging quenches
#2, 3 post forging quenches
#3, 6 post forging quenhces
#4, 9 post forging quenches

Rex noted a steady progrression of greater uniformity in the steel from 0 to 9 post forging quenches.

Since we started using the 30 second post forging quenches blade warp has become an event of the past. Not one blade has warped since we started using them. While the steel was most uniform after 9 post forging quenhces I feel 3 is the number that provide the greatest benefit to the kind of blades I want to make.

I have only had time to run one experiment seeking to compare
the performance qualities of 3, 6, and 9 post forging quenhces.
The blade with 3 post forging quenches proved to be the best at cut.
This is a conclusion based on a limited data base, more experiments are needed to  confirm these results.

One interesting result of the experiment:
I forged the samples I sent Rex just like I forge a blade. All hammer blows were to the edge and sides of the blade, no forging blows were directed to the spine.

Rex was able to identify significant differences in the grain structure in the spine vrs the area that would have become the cutting edge.

This adds credence to the thought that the nature of the forged blade starts with the first hammer blow.
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« Reply #4 on: September 21, 2007, 07:11:22 PM »

While at Blade Show West I was talking to knife maker Lyle Brunkhorst, he related a lesson he learned while making knives with some 1095 he had purchased. No matter how he heat treated when he tried to flex the blades to 90 degrees they broke at about 10 degrees, snapped like a piece of glass!

He stated that he did some experimenting and gave the blades a soak at critical temp and let them cool down slow, then proceded to forge blades. After that treatment the blades easily completed the 90 degree flex test.

In our DVD Rex and I mention the critical soak, we bring our billets up to critical temp and soak them at critical for 2 hours for every linear inch to the center of the billett. Once we started using this thermal cycle before we start forging the billets down we have enjoyed a greater degree of reliability from our steel, evidently it removes one unknown variable.

We found this thermal cycle to work on 5160 steel from unknown sources and 52100, thanks to Lyle we now know it will work on 1095. If you are having trouble getting performance out of other steels I suggest you give the critical soak cycle a try.

Rex will try to post on this subject tomorrow.
« Last Edit: September 21, 2007, 07:16:37 PM by Ed Fowler » Logged

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« Reply #5 on: September 21, 2007, 11:12:05 PM »

For more on Lyle's thoughts see:

http://www.bronksknifeworks.com/Knife_Articles.htm#Heat%20Treat
« Last Edit: September 21, 2007, 11:14:03 PM by radicat » Logged
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« Reply #6 on: November 09, 2007, 09:55:38 PM »

The following are some questions I received from another maker who is about to start working with some of Rex's 52100. I decided to post my answers here  just incase others have similar questions and to discuss variables that can influence the nature of our blades.

Maker: You mentioned that you gave the steel a "special treatment" in the Paragon, but I do not know if you annealed it or whatever. Can I ask you what this special treatment is?

Ed: We have no secrets from anyone who asks, always feel free to ask if you have a question.

When I receive my steel from Rex I heat it to critical temp in my Paragon and hold it at this temp for 2 hours for every linear inch to the center, then let it cool down naturally in the Paragon to room temp. This is a step we learned the hard way, when knives from one billet failed.  Sometimes funny things happen to steel. Maybe our steel was overheated or ?  This heat in the paragon is a cycle that puts all of the steel I work at the same place metalurgically. Call it a step toward uniformity.

Maker: I remember that you forge under 1650, so I will do the same. I am confused by the emphasis on forging one side as the spine and the other as edge. Am I wrong in thinking that the anvil pushes back with the same force that  the hammer puts in? This is basic physics is it not? 

Ed: The side hit by the hammer receives a more concentrated force than the side on the anvil. If you doubt this just take a board and lay it in sand and hit one side with a hammer, you will see the dent in the board, but the force will be distributed through out the side in the sand. When I get my steel from Rex, it is in 3 x 3" x 14". I mark the bar that I weld the billet on randomly decideing which side will be the future cutting edge of blades and the oposite side the spine. All future hammer blows will be to the future cutting edge and sides of the blade.
Rex can see the difference in the microstructure of steel before any heat treating, when I send him unheatreated steel for lab work he knows which is the intended edge through photomicrographs.

We know that forging can improve this steel, we also know that the hammer is responsable for the improvement, why not put as much as we can into the business part of the knife? How great is this difference? I don't know, but there is a difference and why not take advantage of every opportunity we have to develop the cutting edge as far as possible? This venue of physics is called the resolution of component forces, one of my favorites!!

Maker: Regarding hardening the balde, how hot do you pre-heat the oil to?

Ed: I pre-heat my Texaco Type A to 165 f. this is has proven to give me the best performance the way I work my blades. It may very well be that another oil temp may be better for you and the way you work your blades. Have fun with it when you decide you have time to fine tune your methods.

Maker: I know that you go to non-magnetic with a torch, but for me I've tested this in salts and recorded that my 52100 (after numerous normalizations) is non magnetic around 1420 degrees, but I did not get good results from this. I hardened the blade much better when I heated the blade to around 1500 degrees f. Do you think it is possible that you are actually going 50-80 degrees hotter than non-magnetic?

Ed: It may very well be that I don't always hit the exact temp, although I do try to keep it as close as possible. There are several variables to be considered here. All thermal couples are not absolutely accurate, the chemistry of your steel may have varied from mine, and our methods of working the steel to the time of heat treat may vary.

The bottom line - you are testing your blades and asking questions, this is a good thing!! Do what you have to do to develop the kind of blade you want to make. I always test for chip, then cut, then I know. You will have to do the same. Maybe one day we will be able to work together using the same steel and come up with a better answer.

Maker: In tempering the blade I've noticed that doing things the way I do it, I get the best results when I temper my 52100 at 480 degrees. Other people I talk to use 385 f. Did I get it right? Do you temper at 385? My edge chips out like crazy at this temp and it won't cut more than 30 pieces of rope. When I do it at higher temps I get much better results. I know that there are tons of variables in the heat-treating process, but I just can't fgure out why, when usign the same steel, I need a tempering temp. almost a hundred degrees different?

Ed: Last year I tested a blade that had been hardened in salts, it performed much like you described, but when I got it tempered so as not to chip, it lost all ability to cut. Maybe the salts are a contributing factor? I don't know as I am genereating an observation from a data base of 1.

The way I work the steel now, I always temper at 388 degrees, 3 times over 24 hour intervalls. In the oven at room temp, to 388 degrees in one hour, hold for 2 hours, cool down in the Paragon with the door closed to room temp, then back into the freezer.

It may be that my Paragon thermal couple is a little off, that is OK because I found that tempering temp by testing my blades. My thermal couple sets the temp at the same heat every time, that is what counts, the numbers are just a refference. If I find a blade that still chips, I go back to the temper for three more cycles 10 degrees hotter and continue until the blade quits chiping then test for cut.

Working with the same steel and working it carefully I have not had to change my tempering temp for a long time. This is the beauty of working with the same steel always!!! I dearly love the opportunity Rex provided with this steel, it is a true blessing.

Thanks for the questions and good luck!
« Last Edit: November 09, 2007, 11:21:27 PM by Ed Fowler » Logged

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« Reply #7 on: October 02, 2008, 05:17:19 PM »

Hi to all from Argentina.
This is a question for Ed. I recently watched the Dvd 52100 wootz (which, by the way, is great!) and have the next question;
Did you find out what exactly happend to the blade you test in the movie, since the first time you tested it for rope cutting (which you say did very few cuts) and the second time you test it and did great in the same task?? 

Manuel Q
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« Reply #8 on: October 02, 2008, 09:53:17 PM »

When she was hardened she was only taken to the low end of the critical stage before quenching in oil in the hopes of preserving the grain structure that made Wootz great. At first performance was not great, she did not cut like the blades taken higher into the critical stage.

Evidently time and the moderate thermal cycles she knew in my shop and refrigerator allowed further hardening or (?). The only way we could know would be to make another just like her and let Rex cut sections of the blade for examination with his microscope immediately after she was completed.  She sat in my shop for some time before Rex came to share time with me. Presently this laboratory analysis is not possible.

Yours was a very good question, I sincerely wish I could provide an exact answer. Look at it this way, you can do the experiment yourself and see if you can achieve similar results.

I feel knife making is an art, it is up to science to explain what happens. I do know that the echoes of all knife makers who have provided me with knives to study and those who participated in the development of what we have achieved, as well as the many authors and folks like you who ask questions are a part of that blade.

I am very pleased you liked the DVD and encourage you to enjoy the information in the knife you make.
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« Reply #9 on: October 03, 2008, 08:58:00 AM »

That is a nice challenge, I shall do that.
Just now I have,sitting in my shop, a nice 52100 blade forged from a 2" billet at low forging temp, 3 quenches post forge, 3 normalizing cicles (2 flash, 1 complete) and annealled over night in the forge; wating to be hardened.
Some questions:
1) did the blade got to nonmagnetic temperature o was just loosing the magentisim when you quenched it??
2) How much time did it pass since the time you quenched it and the time you re-tested for rope cutting??

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« Reply #10 on: October 03, 2008, 04:51:37 PM »

The blade was barely magnetic when quenched. I believe I had it at the same temp all three quenches.

I am just guessing but at least 4 months had passes between the first test and Rex"s visit.

On thought - when we were annealing our blades in the forge, we did not get uniform results. Some blades laid over on their sides and the result was  that the side laying on the forge floor was different than the one facing up.  I also believe that our forge was too hot, you do not need to go over 988 degrees f. to soften the blade enough to drill and grind easily. This is where the Paragon oven comes in so handy.
Just something to think about.

Thanks Friend
Ed

I love your questions, your enthusiasm is a breath of fresh air!
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« Reply #11 on: October 05, 2008, 03:56:49 PM »

Thanks for the info.
I'll let you know when a quench it. I don't have at the time a torch, so the hardening will be to the complete blade. I don't think that should affect the experiment, but who knows...

I'thinkig on using as a guide for quenching (and a duplicable variable) the temperature the steels gets when it momentaniusly re-heats on cooling (do you know the precise temperature in which 52100 does this??). I have seen that at that moment the steel is becoming magentic but not so much yet. 

I'd really like to know your opinion on this before I do it.
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« Reply #12 on: October 05, 2008, 05:11:11 PM »

You want to harden on a raising heat. Trying to hit the right temp going down is pretty tough and seems to be vary with the degree of grain refinement.  This is a variable I have wanted to play with but have not been able to afford the hardware required to read temperatures accurately enough - quick enough. One could do a lot of experiments with this set of variables.

The times I have tried to harden while temp is going down were all wrecks. That does not mean carefully controlled experiments could not be fruitful.

Try placing a gauge block like my aluminium table in your quenching oil to regulate the depth of the quenching oil on the blade, this should keep the back soft. Be very careful to avoid hardening the tang, this is always a wreck. Be sure and quench with the cutting edge down.

Also, chose your quenching oil wisely. Many claim "Vet Grade mineral" oil is good enough. I checked into what "Vet Grade" mineral oil was, there was no official standard. Those who feel they have a reliable quenching oil using "vet grade" are only kidding them selves and leading others astray.

Based on all our experiments: what you want for best results is a slow quench oil, (18 - 20 second) down through critical. ASTM has standards and if you know the speed of your quenching oil you can know good times and can duplicate your experiments easily. If you don't now the speed of your oil you are in never - never land.

Should they tell you it works for them, ask them how they test their blades and what differences they noted contrasting their "Vet Grade" mineral oil blades with blades quenched with other oils and then ask what the speed of their "Vet Grade" is.

You will find things get quiet real quick. Either that or they will talk around your question.
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« Reply #13 on: October 05, 2008, 09:02:39 PM »

Ed is right on the mineral oil, way to fast. Tried it on two blades, warped both times, tried cutting it with tranny fluid, still no good. Later, after I got some Tex type A, straightened the warped blades, did my 30 second quenches and normalizings and they came out straight as an arrow.
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« Reply #14 on: October 06, 2008, 08:24:25 AM »

You want to harden on a raising heat. Trying to hit the right temp going down is pretty tough and seems to be vary with the degree of grain refinement.  This is a variable I have wanted to play with but have not been able to afford the hardware required to read temperatures accurately enough - quick enough. One could do a lot of experiments with this set of variables.

The times I have tried to harden while temp is going down were all wrecks. That does not mean carefully controlled experiments could not be fruitful.

Try placing a gauge block like my aluminium table in your quenching oil to regulate the depth of the quenching oil on the blade, this should keep the back soft. Be very careful to avoid hardening the tang, this is always a wreck. Be sure and quench with the cutting edge down.

Also, chose your quenching oil wisely. Many claim "Vet Grade mineral" oil is good enough. I checked into what "Vet Grade" mineral oil was, there was no official standard. Those who feel they have a reliable quenching oil using "vet grade" are only kidding them selves and leading others astray.

Based on all our experiments: what you want for best results is a slow quench oil, (18 - 20 second) down through critical. ASTM has standards and if you know the speed of your quenching oil you can know good times and can duplicate your experiments easily. If you don't now the speed of your oil you are in never - never land.

Should they tell you it works for them, ask them how they test their blades and what differences they noted contrasting their "Vet Grade" mineral oil blades with blades quenched with other oils and then ask what the speed of their "Vet Grade" is.

You will find things get quiet real quick. Either that or they will talk around your question.

Just my $0.02 cents worth

Working with a lot of Vets over the years and noticing they have a couple different types of oil they regularly use.

If anyone have seen a Vet 'tube' a horse, were they take a long tube and slip it in a horses nose and down into it stomach. The Vet is trying to treat a horse that has coliced. The mineral oil they use for colic has been homogenized to hold moisture and  would be a faster quench.  (and not consistent)   

If I may mention what I have been using, by first explaining how I test my knives?

After the final temper (3 two-hour tempers)

Testing for chips first, hacking bone and wood-knotts, rod testing, shaving bronze and finally testing the knife on a horseshoe, whittling small iron shavings will sometime fold the edge slightly, but I expect no chips.

Then cutting test, numbers here are moot, but I like to see at least 10-times the cuts I can get out of most any popular factory hunters. I like to use 3/4" sisal (manila) rope from Home Depot as it would be avalible nationally if someone would like to make a long-distance comparison. 

Hoping to get up to the Willow Bow someday, till then I feel comfortable with the results of my testing.

My oil......

Going the route of many here, I tried everything, and everything at different temperatures, heating oils in a very old deep-fat fryer that I modified the temp control sensor to be more accurate in the 150 Deg. range.

Drain-oil, Hydrolic oil, transmission fluid, new and used, vegetable oils and have learned a little something from each one along the way! (like all oils will draw moisture out of the air and needs to be brought up above boiling (212 deg.) regularly, try heating your oil there, if it's noisy at boiling temps, it gained water?)

What I am getting consistent results with now is 100% pure Mineral oil, that being said, it still needs to be boiled to make sure it is not retaining moisture, and then cooled to your quench temperature.

Having gone to this medium, I have seen the need to raise the temperature of my tempers and have gained cut ropes tremendously.

Currant test are including triple quiches starting at 145 deg , 2nd quench at 155deg and the final quench at 165 deg . The progressively faster quiches may not be doing a lot to the steel, by the 3rd quench there should be no retained austenite,  the blades do seem to take an etch quicker and with slightly deeper (further/higher martinsite ~ less soft-spine)  and crisper transition-line(?)

Knowing full well we need to be confidant with what ever we practice, if anyone is ever in the Denver area, bring your knife! and some rope, or we can use some I got from Home Depot , there are always things to learn!
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