what method do you use?

Riced....

Hi this is Daqo'tah

I have been asking the guys here your question for months,,,,,so far, I know what everyone "believes" is true,,,But there just is little information I have understood from the world of science, to help me decide for myself...


I used to just use 5160 auto springs to make knives out of,,,then due to some advice I got from a topic much like this one here,,I changed and now I use John deer load shafts,,,and it's been fun, and work.....Fun that I had to get a real gas forge, and work because I bang the steel shafts by hand and it's takes hours to get the steel to the shape I used to start with ,when I used springs.


But as for the heat treating and quenching?.....Ed Fowler does it 3 times,,,,His advice is to do this many times based on things I dont understand, but it works for him , and he is way smarter than I will ever be,,,

So I do 2 or 3 quenches on every blade I make,,,I etch to check my work,,,,I do 2 temperings at 330-350 for no reason I understand, but again, it seems to work...

I have had good luck,,,but...

BUT to tell the truth,,,I wish there would be way more tests on this type of Heat-treating Im doing so that I can point to real proof as to why it works,,,I would really like to know what changes in the steel by the 3rd quench that is so darn different than the 1st quench?....sometimes I get an answer from posters that say that the steel grain gets better after the 3rd quench,,then i get other answers that say that the only thing that might be helping my blades is that by the time I do the 3rd quench on the same blade,, I have gotten so good at doing them that i do it like I should have done the 1st quench....


so,,,,the battle to learn this answer goes on.....
 
To deal with the mythical 3s of blade making you should take a lesson from rlinger and do some experiments. Take samples and try 1,2,and 3 times .Then break them and compare fracture surface , and pick which one is finer grained.Then you will know instead of guessing.
 
I normalize 3 times before the quench then quench once then cool completely in a bucket of ice water or put it in the freezer for a couple of hours and then temper twice at 325 for 2 hours each cycle with a room temperature cool down in between the two cycles.

The best advice I can offer is to do some experimenting with the materials you plan to use and the quenchent you will use.I have found that most makers find there own twist on this subject and that is why in the old days some smiths blades were better than others and they kept these things their secret till they died or passed it on to a aprentice they felt was worthy,We all live in different climates with different humidity and temperatures and just different variables,so what works for one of use may not work for another.Find the combination that gives you the desired results you want and stick with them.Heck look at Scagel's formula..Quench in warm oil,polish one sidr of the blade off then heat to a straw blue color over a reducing flame in the forge and cool off in a bucket of room temperature water to stop the tempering,then finish out the knife.And look how well his Blades hold up even now.Yes I have done some this way and it does work,but you have to have a eye that will hit every time or you will be off a few RC's..
Good Luck and have fun in your journey to the perfect Blade,
Bruce
 
Well put Bruce! A lot of people worry more about "The Way", when they should be worrying about there way.

All I can say is the triple quench works for me, on certain steels, in my shop, with my methods. I destroyed a lot of knives and talked with a lot of makers and tried a lot of methods to get the results that I'm getting now, and still I test and experiment to try and improve. I imagine it's the same with a lot of makers.

From what little I understand if you hit everything right a single quench is as good or better than three. I generaly cant' hit it that close so three quenches works better for me.

The frezer thing, well I don't know, but I also noticed a slight increase in edge holding, after each quench and the blade has cooled down I leave it in the freazer over night. Not much increase in edge holding, but enough for me to warrent doing it.
 
Will 52100

You always give me good advice...

now here is my question for you today:

Im heat-treating the cutting edge of the blade with the O/A torch. I get the steel red, then real red,,,I test with magnet and it seems to not stick to it so I "think" its about time to quench...But then I always pause, for there is a brighter/deeper color on parts of the blade,,so i keep heating to try to get the rest of the blade this deeper/brighter color,,,
BUT,,,but by the time I get the whole cutting edge the same cool color,,,I have by now heated the blade untill it's about all the color red.

Then I quench, and as i set the blade down on my little quench tank table (like Ed Fowler's) I notice that the color red seems to climb up to the parts of the blade i wanted to stay soft...


QUESTION: From what I have just writen, would you say there is something going on wrong in my system?
 
okay,,,thats brings up another question dealing with heat-treating 5160 steels

If I decided to do only one heat/quench and not the 2 or 3 I do now...what is the best way?

I use a O/A torch, heat the cutting edge, then quench,,

Is that about all a guy does?

I know that some ideas migh help a litle like the cyro-freezer stuff,,,,But as far at the actually heat-treatment goes, is what im doing now about as much as I could ever hope to do ?
 
Well, to me and my eyes in my darkened shop criticle temp looks more orange than red to me. The way I do it is go to the brighter color your talking about. Normaly I quench in the evening with very little light in the shop, easier for me to see the little variations in color. From what I understand criticle is just a little above non-magnetic. Just make sure that the areas that are brighter are what your checking with the magnet and by the time, should be a second or two, you've evened the color out it's into the quench.

I know what you mean by the whole blade getting hot. Shouldn't cause a problem with an edge quench and if done right the spine of the blade never reaches criticle so won't transform. On larg bowies I usaly heat to criticle in the forge, bringing the whole blade up to temp. Since the blade is edge quenched the spine and tange don't get hard as there not in the quenchant. One old method of quenching was to heat the blade up and and when the edge reached criticle the spine was still cooler and quench. since the edge got hot faster than the spine it was ready for quench befor the spine was up to criticle temp. This method requires a lot of practice and maybe a little luck to get right. I prefere the edge quench.

As for the single quench I used the method you described for a while befor I found out that triple quenching works for me. The thing with a torch is that it's harder to get precise temp control and a single quench needs to be right on the money. It can be done, but the best way is for you to make a couple of blades, one quenched once, and one quenched three times and test till destruction, starting with rope slicing to find any gains or loses with cutting ability.

You shouldn't have a problem with frezing blades where you live, at least in the winter. I would sugest leaving them in the frezer overnight to even the blades heat treat so that it's similar to what you do in winter.
 
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