Does this make sense to anyone?

R

RobertHankins

Joined
Jun 10, 2001
Messages
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When quenching a Carbon steel blade in a tank...Would it make sense to put a small circulating pump to make the oil move around while quenching a blade???
From what Ive read and practiced it is best to move the blade back and forth while quenching to get a faster quench. Wouldn't the logic follow that if the oil is already circulating this would work better...
Any thoughts...
 
I have had the thought of making a quench tank that circulates the oil from the bottom back to the top myself...So I will be watching this thread for some input from others as well.

Thanks for bringing it up.


Mike K.
 
Yep sounds completely right to me but it probley is one of those things that will work but isnt actually worth the time if you want give it a shot I wouldnt mind hearing if it actually worked beter enough for it to be worth the trouble
Bryce
 
From what I have been shown and told. It may cause problems.
I was told to cut the blade through the quentch witout side movement so that it did not worp the blade. That is cutting through as if cutting something NOt as in spreading buter or stiring tea. I don't know if this is legend myth or science. SO Its just comment not advice.

The other thing I notice is if you put the blade in vertical thermal dynamics seem to be at work the hot oil looks to me like it rises and is replaced by colder. I would be more inclined to just get a bigger quenching container so there was more cool oil to circulate.

I have not done any high tech quentches I am just refering to the
average servicable knife.

Sure we should all try for the best edge we can with the high tech gear unfortunatly the above is all I can afford for now and it provides a good workable blade. If I did the other treatments I would use that as a selling point to justify higher prices.
 
Robert, I just read something about that.
Sorry I can`t remeber were(old man you know)
As soon as I can get a buddy of mine weld me
up a SS tank I`m going to give it a try
 
Somebody had a backdraw setup that had a copper tube with water running through it that I thought was pretty neat.It looked like a slit was cut in the pipe to put the blade in. I believe if you got real creative you could set this up to give a patterned hamon . I dont see why you couldnt use the same setup for a quenching device. It may have been Graymaker or blackboogers...?

Mark
 
Reg,
You are right quenching is done with a slicing motion. Back and forth to keep the oil from superheating and just bubbling around the blade. You want as much cool oil in contact with the blade as possible especially for the first minute or so.
Just wondered if someone else has tried this before I re-invent the wheel.

A small pump used on a milling machine for coolant should work and not be too expensive.
 
I use a vertical three foot piece of four inch diameter steel tubing to quench in. Blade is inserted straight down point first about a foot deep. Then I move blade up and down about 6 to 8 inches during the first fifteen seconds. Whatever is going to happen is now over with and I let blade hang in the oil about five minutes until I can hold it with my hand. My quench oil temp window is 120 to 150 degrees. At no time is blade moved through oil like an oar as side loading pressures will bend hot steel.
 
Typically I do an Edge quench. Just trying to optimise the process and get consistancy.
I am sure just a very little movement would be needed to keep the oil going.
 
Hey Robert, check this thread out:

http://www.bladeforums.com/forums/s...perpage=20&highlight=QUENCH PUMP&pagenumber=2

Sweaney responded on the second page with this:

"If you are doing a bunch of knives then you need volumn to keep the ambient temp of the quench where you want it to be.

If you quench one or two at a time no big deal.

A circulating pump or air stream in the oil helps to keep it stable.

A friend of mine used to heat treat batches of wrenches at a time. he said they used an air pipe in the bottom of the tank, with holes every so often to keep the oil stirred."
 
mechanical agitation of the quench medium via propellers, or compressed air, etc is common for large scale industrial HT where maximum cool down of large objects (or large quantities of smaller objects) is required. by equalizing the temperature of the quenchent it would delay the overheating of the quench some too. 'probably would serve little purpose for knifemaking.
 
Most of the steels have between 1 to 5 seconds to miss the pearlite nose on the Time/Temperature chart. The hot quench will cool the steel faster than a cold quench because it will circulate up the sides of the blade. Any side ways motion will cause that side to cool a little faster and will cause the blade to warp in that direction. Both sides of the blade need to cool at the same rate. That is also why it warps when the grind is uneven (more steel on one side of the blade than the other). I heat my quench to about 300 degress so that the blade temperature will stay in the martinsite transformation zone longer. After the steel cools to about 175 degrees F., the transformation has stopped.
Hardening times for 1070, 1084, & 1095 is about one second.
52100 is about two seconds and O1 is about 10 seconds. This is the time frame to get down to about 1000 degress and then you have probably close to 45 seconds to reach 475 to 425 ( where martinsite starts to form). I hope I haven't confused the issue. I really don't think that a circulating quench tank would offer any benefits over using a hot quenchant (for knife blade applications). It would benefit a large piece and the large piece would also have to be a deep hardening steel, such as O1.
 
Ray,
If I may ask... What oil are you using and have you noticed a shortened life of the oil by running it to 300* and holding it?


Thanks,
Mike K
 
Robert,

Novice as I admittedly am, I would rather not oil quench as you ask about. It should take but a few seconds, say 7 for example, to quench and pull at the proper temperature. With such little time involved I would rather have control of the steel and be sure all parts were consistently coated by quenching oil during that short and most important period of time. Cut the oil back and forth delibertly but not in too much of a hurry as to slush the oil. Pull so it smokes but does not flame.

However, I don't know except what I've been taught by those I believe to know.

Roger
 
Mike,
I use dextron II for the quench and an electric skillit for the heater. I just set the thermostat on the handle and check the temperature with a little digital thermometer. The 300 deg.isn't quite so critical as it is to keeping the temperature of the steel in the martinsite transformation zone (475 F down to 175 F.) for the 52100. I usually leave it in for an hour and then unplug the skillit. Once it cools to 175, it is over and you can take it out and wash it with soap and water. I temper at 475 for 2 hours twice with a cooling period between the temper cycles. It kind of turns dark but it still cools quickly. A skillit doesn't hold a lot. If I want to do a large blade, I have a 3 inch tube with a plate welded on the bottom of it to set in the skillit. I quench point first on the longer blades, and then just leave it in the pipe for an hour. I use a magnet to test for the critical and it has worked very well for me.
 
Just my opinion but I think your better off experimenting to find the right oil to quench in to get the results you want rather then worry about circulating the oil. For example, 52100 will harden very well in ATF heated to 160 degrees but then the blade must be drawn back at a temp of 450 to get them to pass the brass rod test and they won't make a 90 degree bend without breaking, BUT the same 52100 will harden just as well in chevron super quench heated to 160 and the draw temp will drop to 375 for the blade to pass the brass rod test, and the blade will easily make a 90 degree bend without any cracking and still rebound to nearly a 25 degree bend.
Just drill several holes in your depth limit plate in your quench tank and the oil will circulate its self to a certain extent, if your doing several blades you might have to had more oil to you tank to cool you quenchant down to keep it in your heated limits, but that would be only if you were to do several blades in a very short time.

Just my 2 cents, good luck

Bill
 
Raker,

That's cool the way you heat the oil. I soldered three large coffee cans together to get enough depth. I set can assembly in a crock pot, put water in the crock pot to fill the void, turn the crock pot to high and clip my digital kitchen thermometer to the lip of the can assembly. When it reaches about 140 F. I'm ready to fire the forge and start cooking. Actually I did not assemble those cans for that reason. I had done that some time back with the idea of using the assembly to soak rifle stocks in to remove old finishing oils and such. I never got it finished by soldering enough cans together for a rifle stock but the three I had turned out just right for short and long blade quenching.

Roger
 
rlinger,
One time I soldered a bunch of 3 pound coffee cans together, the two open ends to make a float. I would solder an eye on the end to tie the jug line and put a big rubber inner tube band around it to put the hook in and was ready to go to the lake. Then I read the regulations and "no metallic floats allowed" :(. I did get good at soldering. :)
Bill, the 52100 I have will chip at 450 degrees and it bent very good when used for my JS test. After I got the JS stamp, I straightened it back out and sent it to Cliff Stamp to play with for a while. It is probably just my particular batch that responds this way but it has been doing very good. Most people will usually start at the lower tempering temperature to find out at what temperature is best for that particular steel.
I haven't really figured out what I am doing is called yet anyway. i have heard "marquench" and "mertemper" and the graph for them is not exactly what I do. I don't know what it is called but it has worked for me. I was fortunate in that I got 4 tons of the steel to start with so I have plenty to work with for a while :).
 
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