Quenching tank

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Natlek

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Jun 9, 2015
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This will be my quenching tank ,all from stainless steel .Will hold about two gallon oil .I want to make it to agitate oil inside .I see two option , fan on bottom of tank or external oil pump .With fan looks to me little easier to make it.What do you think ? Or better to ask how you solve agitation in tank if of course you have that feature in your quench tank ?
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http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392005000400018
 
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This has been dealt with by Kevin Cashen and others before. The simplest is to make a long rod with the impeller on the end. Make brace that will j]hold it centered and about 1" above the bottom. The impeller should be about half the tank diameter. At the tank top add a brace to bolt a 1/10HP motor and attach the long shaft to it. Th shaft should be at the side of the tank at the top. Have the impeller direction so the oil is forced upward. A small 3PH motor and cheap sub-HP VFD works really good here. You have to quench the blade so it goes just to either side of the impeller shaft ... and obviously not as deep as the impeller.

The second method is better because the quench tank has nothing in the way of the blade, but takes a little more work. Make a second tank about 2" in diameter and as tall as the quench tank. Drill through the side at the bottom and 4" from the top. The motor and impeller mounts on the top of this with the shaft going about half way down the center of this tank , Drill matching holes at the bottom of the quench tank matching the ones in the pump tank. Weld connector pipes to them so the two tanks form a loop. The impeller forces the oil down the small tank and into the bottom of the quench tank. This forces the flow upward and the oil returns to the pump tank from the top cross pipe.
This setup also increases the cooling surface of the tanks to keep the oil cooler longer.

Now, I will address the size of your proposed quench tank:
2 gallons is suitable for a single small knife. If you need the oil moving and the quench speed is critical, use at least 5 gallons. This will also allow more blades to be quenched in a row.
 
I was planing to mount impeller from bottom side , Stacy ? No way that I would do what you suggest , it is to much complicated and very impractical for use ?
This is what I was thinking to use if I go that route with impeller instead of pump.
Water pump from car engine .............They are perfectly for this and very easy to adapt and to seal on bottom of quench tank .I can change easy that fan/impeller with right one if needed ? I can t see any problem if I use one ?

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About the amount of oil ....one blade at time that is all I need from this tank ? I have read in many places that rule is one gallon per pound steel ? Even less if agitation system is used ? So two gallon are enough for one small blade ..max.5mm thick and 10 inch long , right ?
What do you think about pump instead of impeller ?
 
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It will probably make enough agitation to get some sort of upward circulation, but that type impeller draws from the center and ejects from the side. Spun the reverse direction it will cause some upward flow.

To get a directional flow you have to mount a housing with an outlet over the impeller, but in a open system like a quench tank, it will work.
 
How are you planning to heat the oil? And how many blades are you planning to do?
If you're doing a lot of blades you'll want more capacity and external pump would help with that (you could even run it through an oil cooler if you want to get complex). If you mount something to the bottom that will add a bunch of stuff on the bottom and make it less stable.
If you're only doing one or two blades I would just make a long stirring sick, heat that up and use it to stir and heat at the same time. For my incredibly crude setup i heat up a pair of tongs, stick them in the oil and use them to stir it around.
 
Alex Topfer said:
How are you planning to heat the oil? And how many blades are you planning to do?
If you're doing a lot of blades you'll want more capacity and external pump would help with that (you could even run it through an oil cooler if you want to get complex). If you mount something to the bottom that will add a bunch of stuff on the bottom and make it less stable.
If you're only doing one or two blades I would just make a long stirring sick, heat that up and use it to stir and heat at the same time. For my incredibly crude setup i heat up a pair of tongs, stick them in the oil and use them to stir it around.
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Yes , one or two small blade at time .....Tank would be fastened to the floor in one place so no worry about stability of tank .
Quenching is very important part of HT proces .It does don t mater if you grind blade on best grinder available or on worse one , you can have the best best HT oven BUT if quenching is not done right . . . and tempering as a last step ??
There was a lot information about this on net ....but most are for big industrial quench tank .This one is good to read for example .. http://kubanni.abu.edu.ng/jspui/bitstream/123456789/9154/1/DEVELOPMENT AND PERFORMANCE EVALUATION OF AN AGITATED QUENCHING TANK BATH.pdf
I have general idea how to do this but as they say the devils is in details :) so I was hoping that someone here will share some details ...
https://www.globalspec.com/learnmore/flow_control_flow_transfer/pumps/impellers

https://blog.craneengineering.net/introduction-mixer-impellers-flow-patterns
 
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I set up my circulation quench tank using a 12 gallon water heater to hold 10 gallons of oil. The in and out piping went to a fuel/transmission oil pump (12VDC) and there was a transmission oil cooler with a 12VDC fan in the same line. The fan was connected to a thermocouple that turned it on when the oil rose to 130F. The heating element on the tank (120VAC) was set at 120F. The oil pump ran all the time to circulate the oil from the top of the tank and return it to the bottom. I made a short copper tube with an elbow on the end that stuck inside the lower pipe fitting so the oil was directed straight up the middle of the tank.
It worked very good, but was not needed once I started sending blades out for HT in batches. I still have it stored away for future use in the new shop.

The old photos are long gone, but here is a build tutorial on it:
https://www.bladeforums.com/threads/10-gallon-quench-tank.396663/

I also made a 4 gallon version that used a 5 gallon water heater.
 
Thanks @stacy ,I really don t need to cool oil , no need for one blade . You know what ? I was thinking several years to ask this .......We need agitation to break the vapor barrier, right ? So what if I use let say 6 foot long tube filled with oil and drop blade inside to free fall right to the bottom ? Isn't that same as agitation :eek:
 
That is exactly why a quench tank should be twice as deep as the blades quenched for knives. Plunge the blade in and push up and down. No need for a longer tank, all that matters is the first one second.

I just remembered another really simple quench tank agitator/circulator.
The tank was about 24" high and 4-5" wide. There was one piece of copper tubing ( looked like 3/8" or 1/2") that went over the quench tank opening and down the inside, then made a circle of the bottom (to keep it positioned in the bottom), then turned upward at the center of the bottom. There was a second tube that went over the edge , down about 3" below the oil, and circled the tank ( again to keep it in place), leaving the end pointing sideways. These were plumbed to a small fuel oil pump strapped to the tank side. The pump was controlled by a light dimmer switch to get just the right amount of circulation/agitation.The arrangement made a nice rolling upward current of oil in the tank.
 
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Stacy E. Apelt - Bladesmith said:
That is exactly why a quench tank should be twice as deep as the blades quenched for knives. Plunge the blade in and push up and down. No need for a longer tank, all that matters is the first one second.

I just remembered another really simple quench tank agitator/circulator.
The yank was about 24" high and 4-5" wide. There was one piece of copper tubing ( looked like 3/8" or 1/2") that went over the quench tank opening and down the inside, then made a circle of the bottom (to keep it positioned in the bottom), then turned upward at the center of the bottom. There was a second tube that went over the edge , down about 3" below the oil, and circled the tank ( again to keep it in place), leaving the end pointing sideways. These were plumbed to a small fuel oil pump strapped to the tank side. The pump was controlled by a light dimmer switch to get just the right amount of circulation/agitation.The arrangement made a nice rolling upward current of oil in the tank.
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Well this sound good , no hole to drill and no welding ...I like this idea , if I go that route I will use it . Easy to do , just little bending thin cooper tube and I have that tool :thumbsup:
But I will try with long tube , too :D No need to be big in Dia ,will hold blade from turning ...... My workshop in my home once long time ago was garage where I start to work on cars so I have car repair channel inside . Now it is covered with planking , but ... it is about 5 foot deep so + 3 foot out ....I will have maybe two or three second to sink to bottom through oil :)
 
Natlek said:
Well this sound good , no hole to drill and no welding ...I like this idea , if I go that route I will use it . Easy to do , just little bending thin cooper tube and I have that tool :thumbsup:
But I will try with long tube , too :D No need to be big in Dia ,will hold blade from turning ...... My workshop in my home once long time ago was garage where I start to work on cars so I have car repair channel inside . Now it is covered with planking , but ... it is about 5 foot deep so + 3 foot out ....I will have maybe two or three second to sink to bottom through oil :)
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I retrofitted my quench tower with baffles to make sure that I have a strong bottom-to-top flow. Also, I learned the hard way about using copper tubing with mineral oil quenchant that it will contaminate the oil--turns it opaque and green. After dumping the oil and copper tubing, I went with aluminum tubing. I used the tubing for my closed system quench oil cooler. This allows me to do several knives with my small quench tower, while cooling the oil back to 130° F between quenches. I currently use a laboratory mixer for agitation, but I like the idea of a curved tube on the bottom, so I may try it. I have a paper on our website regarding baffles and my oil cooler--www.bellablades.com. Again, thanks for the curved tube idea.
 
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