Ed,
Can you explain why heating the quench medium will result in a faster cooling rate. I heat mine to about 140 to 150 degrees for quenching 5160 and have good results.
Thanks, Dave

Welcome to the forums Dave. I think Ed is still out of pocket.

One thing heating does is lower the viscosity of the quenchant, allowing it to wick away heat from the steel more rapidly.

Terry is right.
The heat thins the oil and allows it to BITE the metal quicker.
The preheat makes it more fluidic and less mud like.
I preheat( used tranny oil) to about 120-130 degrees.
Hope that helps untill Ed gets back.

What method do you guys use to preheat your oil? I saw Harvey Dean heat up a bar of steel and stick it in the quenching medium a couple of times to bring it up to temperature- is there another way? Thanks!

I've seen some oil-drum heaters in MSC and considered those, but they seem to be designed for 50 gallon drums, which is a bit excessive. Also considered finding a gas ( I have the most expensive electric utility in the country barring California... no, really! ) water heater and modifying it... nice thing about that is turn it on an forget about it. Also considering building a quench tank I can heat with a burner and measure by hand. Sort of like a salt tank.

At present I have a 30 gallon drum of brine I heat to 150 by quenching bars of steel in. Takes too **&^!!! long and too much attention.

I learned this trick from Daryl Ralph, I believe, on Bladeforums (Shop Talk). I took an old electric skillet and cut off everything except that portion of the pan above the heating element. I hang this on the edge of a large stock pot (don't submerge the plug!) that holds about three-four gallons of vegetable oil that I quench in. It takes about 10-15 minutes to heat up to about 130 degrees but I just turn it on first and by the time the forge is ready and I'm all set up it's pretty close also. Works quite well actually.

Guy Thomas

I have three quench tanks. Two of them are used for edge quenched blades. The only difference in the two is their size. One is used for hunter sized blades, and the other is used for for Bowies and campknives.

Anyway, on those two, I use the method of heating up a bar of steel and putting in in the quench to heat up the quenchant.

My third quench tank is for full quench of anything up to about 30 inches in length. It is a controlled quench tank made from a hot water heater (electric). Two or three years ago I traded one of my hunters to a knifemaker is east Texas for this quench tank. I love it.

I appreciate the replies to my question. Makes sense now.

I heat my oil on an old flat hot plate. It takes about 20 minutes.

Thanks again, Dave

Hey Folks. I thought I would share a wonderful thing I happened on a couple of years ago. I had a friend give me a old high school deep fryer. It was discarded because it wouldn't get up to frying temperatures anymore. But, it gets up to the 125 to 135 degree temps no sweat and is perfect for quenching any size knife up to large Bowies. And the wonderful thing is... you can turn it on, set the temp., and walk away. It's ready when you are. Sure beats the days of throwing chunks of steel into a five gallon bucket and screwing with to get the temperature just right, and so on. It only cost me $75, and it's the best $75 I've ever spent in my shop!! Minus the hard core, that is! It holds 7 gallons, has a temp. gauge built in and uses 110. You can get them in resturaunt supply houses that sell used equipment. Oh, and it's all stainless steel, which up to now is the only thing stainless I've ever let into my shop, if you catch my drift !!! HEHEHEH Hope this gives you folks a new idea or two. Will be gone to Boise over the weekend to Rob & Dick Pattons for a small hammer-in, barb'q and some in general, relaxin. Been working to darn hard and my poor feet and hands need a bit of a break. Also, celebrating my wife and I's 3rd anniversary, as our first date was there at Rob's where I took her to her first hammer-in. Broke her in right, you might say!! Regards, Charles

I may be one of the few to also use a deep frier. Since I use mainly air quench steel, mine is used only for tempering. I set it to 400 degrees and walk away for two hours. Works for me anyway.

Gary
Fall Creek Knifeworks