Quench plate ?

EdCaffreyMS

"The Montana Bladesmith"
Oh good grief! Ya'll need to stop goofing around! ..... Just drill channels lengthwise and crosswise....plug all but one entry and one exit hole, hook it to a harbor freight fountain pump, and pump water through it.... just like the water cooled platens!



Hope ya know I'm being factious as all get out! :) I actually don't know which way to go.
 

Chris Railey

KNIFE MAKER
I am not arguing with you guys just participating in a discussion. The idea is to quickly cool the blade not the plates. In my limited knowledge of physics you are spending the energy stored in the knife to heat the plates. Aluminum conducts heat readily so the large aluminum block quickly draws heat away from your knife. I do not think the air exchange of surface area will speed up a plate quench. It may help on multiple successive quenches by keeping the plates cooler in between but I do not see where it will help a quench. I dip my plates in cool water between every quench to keep them cool.
In my feeble mind the mass of the plates is proportional to the amount of heat (Energy) they can store. The temperature of the plates effects the speed at which the plates will absorb the heat. The idea is a small thin knife blade will not store near as much energy as a big fat aluminum plate. When the thin blade contacts two big fat plates the energy will transfer until the blade runs out of energy (Heat) or until the three reach an equilibrium of sorts. That is why you need you plates to be able to store as much energy (heat) as possible which equals mass and the plates need to be made of a good conductor which equals speed. Think of it in reverse terms. Would two 1/8 aluminum plates with or without holes properly quench a 1/4 inch thick piece of steel? No the plates would quickly run out of storage room while the blade had way too much energy (heat) left. Just my opinion on energy transfer as it relates to hardening a blade...
 
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John Wilson

Well-Known Member
The quench plates are fine as is. We’re talking air hardening steel. Any plates at all is already a bonus.

I can dunk my bottom plate easily between quenches but my top plate is bolted. After three or four big kitchen blades the plates are probably getting close to being too hot to be of much benefit to the quench itself which is why I mist them with water. I should probably quit being lazy and make the top plate easily detachable so that I can dunk both of the plates between quenches.
 

latticino

Member
Cross posted with Ember Knives info on the Jay Fisher system, which neatly illustrates my point.:)

Effectiveness of adding fins or holes to a quench plate is likely more a matter of timing than anything else. Quenching happens relatively fast and primarily makes use of the conductive path of heat transfer from the billet. While this transfer rate is directly related to differential temperature of the two materials as well as the contact surface area, the potential heat loss from the quench plate surface to the surrounding environment is via convection, a much slower process (unless you add forced air blowing over the fins). My gut is saying that the increase in surface area just isn't going to keep up with the conductive load from the heated billets, but you can do the math. We are not talking about an approximate steady state process, like heat dissipation from a CPU, but a couple of quick cooling spikes (unless you are setting up a production line).

As Sean mentioned adding water to the mix would be more effective, though the big step in heat transfer there would be when the water changed state and evaporated, so the plates would likely already be hotter than you wanted. Of course if you milled a bunch of channels, sealed them with a back plate, then pumped a constant stream of cold water through that it could be pretty effective.

My guess is for most of us having a method of easily detaching the plates from the clamping system and quenching them whole in a water bucket is likely the most economical option... assuming they are thick enough to prevent warps.
 

jaxxas

Well-Known Member
John Grimsmo's version of quench plates. Of course they are a production shop!

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