New twist on quench plates

JTknives

JTknives

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Jun 11, 2006
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I have been kicking around the idea of trying somthing other than O-1. and i wanted to try an air hardening steel. but im kinda weird and like to try new ideas. so insted of using aluminum for the quentch plates use copper because it transfers heat a lot faster than aluminum. here is the data


specific heat!
Aluminum: 0.900 J/g*C
Copper: 0.385 J/g*C



Thermal conductivity:
Al 237[W/(mK)]
Cu 401

the Lower the specific heat the faster it gets hot.
the higher the thermal conductivity the faster heat moves through the meterial. faster movement means the faster it sucks the heat out of the blade.

as you can see copper is at least twice as good as al.
I had posted this befor but getting my hands on solid copper plates big enought for quentch plates would be very very expensive. so hear comes the twist. im an electrician so i have been collecting copper wire scraps. and i have been cutting them up into very small chunks like the size of rice but shorter. i will fill a contaner with these copper pellets and use it as a quentch tank buy heating the steal up and sticking the blade into the pellets and allowed to cool. the contaner will have a screen on the bottom with a fan to push air through the pellets to keep them cool. this should work very very well. Im looking for small scraps of air hardening steel to try out.

What do you think about this idea.
 
The only problem I see is contact area of the copper pellets will be small, and not cover the blade surface 100%.
The copper will have to have enough airflow through it to make it fluid, so the heat can be exchanged with the other copper bits.
Maybe add some copper powder to help the heat transfer between pellets?
You shouldn't have problems with fusing the copper to the blade, though the melting point of copper is 1984.32 °F, which is close to the temp you want the steel.
 
The point of quench plates is the convenience of not having to deal with oil and the clamping action which prevents warping .Your system will do nothing about clamping ! Aluminum works fine , no need to go to copper. A fine non stainless air hardening steel is A2.
 
ya coverage wont be 100% but it might be more than plate quenching. because a plate quentch does not have contact with the edge bevel. i dont want so much air that it forces the pellets apart.
 
if the melting point is 1984, and the forge is a design that can reach forging temps in the 2000's then just get clay from a potters or craft supply house and mould it over a greased plastic tray and when hard pop the tray out, melt the copper scraps in the forge and pour it into the moulded clay dish. do this twice, file, sand or mill the bases of the copper slabs smooth and hey presto... two copper quenchplates.
 
JT

There might be two little problems with your plan. Copper oxidizes fairly easy -- what is the thermal conductivity of copper oxide? The other problem might arise from the small contact area between your chopped copper vermicelli and the blade. My guess is the point of contact may exceed the melting temperature of the copper, leaving little copper speckles on parts of the blade or even little copper particles hanging from your blade.

Please let us know! You may come up with a new finish!

Jim Arbuckle
 
I think it important to note that too much of a good thing can be a bad thing. Most of these steels can be quenched in air, oil, salt or between Aluminum quench plates. Aluminium cools them VERY fast compared to force air. Copper might be pushing it too far.

I too have my reservations about the effectiveness of point contact and about warping (more like bending) issues while jamming a hot blade into a tank of small copper rods. :eek:

Keep us posted.

Rob!
 
I think part of using plates is that the plates help to prevent warping. Pellets won't help in that respect.
-John
 
Nice idea, but, how do you plan to stick a hot blade that is very flexible into a container of copper pellets without destroying it?

Plus, you have to remove the foil first, which takes time.

Why not melt your scraps and sandcast some plates and have them machined flat?

Or, just use aluminum.........
 
Just to recap the advice being given:

CONS OF COPPER PELLETS
It will not cool at the desired even rate because of the variable contact area of the pellets.
It will be difficult, if not impossible, to quench a 1950F blade into a can of wire cuttings. (I vote for nearly impossible.)
Warpage may well be very extreme in this situation.

PROS OF PLATES
Aluminum plates are cheap, easy to use, and a proven quench style.
There will be no difficulty in using quench plates.
Experimenting with copper plates would be easier and wiser than pellets.
It is easier to blow air between two plates than up a cylinder of copper cuttings.

So:
From a metallurgical and engineering standpoint it does not seem to be a valid idea.
That said, you won't invest more than $20-30 building this setup, and you won't waste more than a couple of blades and a few days of grinding work. So if you want to try it...have at it. Let us know what happens.
Stacy
 
I didn't put this info in the last post because it was not related directly.

If you want to take care of the problem (which is really not that much of a problem) with the distal taper and blade bevel , here are some ways to make the plates adjustable.

First ,quench plates should be at least 1" thick, about 4" longer than your longest blade, and about about 3-4" wide (you don't want them too wide).
Drill holes through both plates for two stop pins that the spine can rest on so you are not trying to hold the blade while operating the clamping mechanism. The stainless pins should be a force fit on one plate, but should have some good slop on the other one (Hole should be conical), to allow for it to become non-parallel. This way you can snip the end off the foil bag, slip the blade right onto the jig (resting the spine on the pins), and clamp.

Now, how to make the plates fit the blade angles?
Easiest way is to just clamp them with only one clamp in the center. The plates will align themselves with the blade geometry as much as possible.

A self -adjustabing jig can be made creating non-parallel surfaces in both planes. (If you understand that statement, you can figure out how to make it. Hint: One plate is fixed and the other is on the cam) This setup is best built as an independent unit actuated by a cam lever. The quench jig will adjust to fit the blade's taper and bevel.

Hope this helps anyone who wants to play with it.
Stacy
 
ive been thinking about that stacy as i make many more kitchen knives then i do hunters and fighters. right not i do not have my plates mounted in a vise jsut sitting in my press. i just off set the press to get full contact with the flats of the bevel
 
Effectively the same thing. Using what you have is good.
Using your head makes you work smarter, not harder.
Stacy
 
ya it might be better to cast the copper into plates. i just like to try new things.
 
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