Heating quench oil

[Randy3000]

Are these cheap immersible drink heater things any good for warming quench oil to 130F?

 

[scott.livesey]

might work. gotta make sure it stays submerged all the time.

 

[joedhiggins]

Decent. Find a fully submersible version and couple with a plug in PID. Work better at the bottom of a vertical tank.

 

[Justin Schmidt]

Just get a camping hot plate at Walmart for 10 bucks and a candy thermometer

 

[Stacy E. Apelt - Bladesmith]

I prefer "rod" or "Drum" heaters on large quench tanks. As said, connect it to a PID and the tank sits at whatever the set point is.

 

[Stromberg Knives]

I use one of these: http://www2.malmbergs.com/product.aspx?item=DV1500

It’s 1500 Watts, and it’s coupled with a PID controller and TC. Works great. It takes about 15-20 min to stabilise at 55 degC.

 

[Ken H>]

As mentioned, the drink heater you show is a fairly low wattage for heating a small volume. You'll find it's going to take a LONG time to heat a quench sized volume, if it ever does. You need something along the order of the 1500 watts mentioned before. A hot water heater type element is good size.

 

[Ian Fifelski]

I am also curious about this. How exact does the oil heat need to be? Is quenching a piece of mild steel before quenching the knife accurate enough?

edit: Sorry, I don't mean to derail this thread.

 

[A.McPherson]

Hey Ian,

That's what I do.

I've got a chunk of mild steel that I throw in the forge to act as kind of a "blast shield" between my blade and the flames. When I get close to ready to quench, I dump it in my quench tank and each the thermometer I have on the side.

When it gets up to 120 or so, I pull it out and watch where it stabilizes. If more heat is needed I do it again.

Works well enough. Just be prepared to put out a fire. glowing steel is hot enough to start cooking oils on fire.

 

[Stacy E. Apelt - Bladesmith]

I have Bill Moran's "Quench Tank Heater". It is a 24" bar of 3/4 round with a 4" piece of 1.25" round welded on the end. For the small quench tank of AAA (about 2 gallons) the red hot rod warms it up tp 120-13-F just fine. The Parks #50 tank does not need to be warmed unless it is wintertime. 60-9-F is the range for #50.

On a 5 gallon or larger tank it takes a LOT of dunking the hot rod to bring it up, so a plugged in rod heater is simpler. With the PID, you can put it in, turn it on, set it for 120/130F ... and go about your business until you are ready to quench. The tank will stay at temp until you turn it off.

I also have Bill's "Quench Tank" ... a 2 gallon white porcelain camp coffee pot ... well, it used to be white. It has a lid, a top and side handle, and he could pour the oil back into a storage pail easily through the spout. There is a strainer built into the spout (to keep the egg shells and coffee grounds out of your coffee cup) that prevents the trash and scale from going into the storage pail.

 

[Randy3000]

Thanks for the replies. I think the cheapest option is the mild steel, and if i get tired of doing that i will get a high wattage immersible element.

 

[joedhiggins]

I see no reason any of the 1000-1500W immersible elements designed for water heaters and the like wouldn't work. Ebay has a billion options.

 

[jdm61]

Or you can buy a turkey fryer at Home Depot and get a quench tank AND a heater.

 

[scott.livesey]

i use a thrift store fry daddy. fill with water, heat till water boils and thermocouple in oil says 115-120F, get quenching. as far as i can tell, most quench oils seem to perform best at 110-130F. you don't need your oil at 127F+/-1degree, so a pid is just an added expense.

 

[joedhiggins]

i use a thrift store fry daddy. fill with water, heat till water boils and thermocouple in oil says 115-120F, get quenching. as far as i can tell, most quench oils seem to perform best at 110-130F. you don't need your oil at 127F+/-1degree, so a pid is just an added expense.

But at $15, a nice convenience. Leave it permanently set to your desired temp and just switch on and off.

 

[jdm61]

I don't know about Parks AAA, but the Houghton version of that "medium fast" oil which is repackaged by folks like Brownells has a "sweet spot." They call it 11-13 second oil because at say 120F and 180F, it is 13 second, but at 150F, it is 11 second.

 

[mete]

You shouldn't be hotter than 130* . It's there to help flow .The hotter the temp the slower the quench !

 

[joedhiggins]

Preheating oil os not only about viscosity. It also changes the thermal conductivity of the oil. To the point that Despite the smaller delta T it cooles a quenched peice faster at higher temperature.

130 seems to be a good max temp for most oils i have used, but there is no hard and fast rule for all quenchants, so it is good to ask the mfr for their recommendations.