Time From Quench to Temper?

Binalith

Binalith

Joined
Apr 22, 2012
Messages
391
I have read a lot about how you should try to go from quench to temper quickly. My question is, since I'm tempering in my home oven, do I have time to wash the blade? I know this sounds silly but if I could be putting a clean knife in the oven it would go a long way toward appeasing my room-mates.

Thanks.
 
Yes, taking a few minutes to wash the blade is fine. I try to wash mine in warm water so they don't cool down too much, but apart from that you shouldn't have any issues...
 
Always take time to wash the quench oil off the blade before putting it in the kitchen range; if you're married your wife will let you know why this is so important. :)
If you get your blades in the tempering oven within a hour or so after quench, in most common steels anyway, you're in good shape. A snap temper, say an hour at temp can be used if you want to work on the blade shortly after quenching it. The rest of the cycles can be run after you finish the clean up grind.
 
Thanks. One more question, does anyone know a thread or site that has what they would consider to be a definitive procedure on home oven tempering? Its fairly simple I know but it seems like theres a million opinions on how many times and for how long each time. Recently I read a thread, here I think, that basically suggested you could leave the blade in forever at some point and the leftover Marsenite(?) would only continue to transform.

Chad: Old American made File. motor oil.
 
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While some people do it, a kitchen oven is not the best for temper. Temperatures can fluctuate +/- 75 degrees from your setting. Place a baking thermometer inside and verify what temps your oven goes to relative to what you set the dial at, and check temp every 10 minutes to see how much it changes over time.

If you are using a simple carbon steel like 1084, quench in canola or peanut oil. When you go to temper make a batch of popcorn to share with your roommates. :)
 
Try canola oil or mineral oil they give much better results and both are edible so even if you put the oil covered blade in you will not ruin your oven.

You should temper for 2 hours then let cool to room temp, this is one cycle. Do three cycles all together. let the oven cycle for 30 mins at temp before putting your knife in it and keep it running between the cooling times, this will reduce high temperature changes.
 
The first rule for oven tempering is the same whether you have a Paragon or a Tappan.

The first rule is - PRE HEAT the oven to the target temp until it is stable. That is usually 20 to 30 minutes.
For a kitchen oven:
Placing a thermal mass in a kitchen oven will aid in evening out gradations of heat. A 16X6" plate of 1/2" mild steel placed on the center rack makes a great thermal mass. Place a 2X2" piece of the same steel on the plate.
Once the oven and steel plate have been at the desired temperature for ten minutes, place the blade on the steel plate .... and place the probe of a digital oven thermometer under the 2X2 block ..... with the probe tip sitting on the blade. Do this and close the door as quickly as possible.
This will allow your blade to be very evenly heated, and allow you to know the real temperature of the blade, not the oven air. When the blade is at the temper target point, start the timer.
Temper for two hours. Check the temperature form time to time to assure the oven does not drift. Adjust the oven setting if needed.
Remove the blade ( leave the oven on and the probe in place) and cool off with running tap water for about 60 seconds.
Dry off and put back in the oven as before for two more hours.
Some people use a third temper, but for any steel but complex stainless steels or high alloy steels, that isn't really needed. It won't hurt anything, but in normal steels, virtually all retained austenite is converted in the first temper, and all martensite has been tempered by the second. 1084, 1095, 5160, O-1 are all fine with two tempers.
Cool after tempering in running water. Slow cooling can cause some less desirable metallurgical situations. These probably won't make much difference, but the best procedure is rapid cooling from temper to room temp. Rapid cooling from temper will not warp or crack the blade, as there is no change in structure occuring.

A basic digital oven thermometer with probe costs about $20-30 at any kitchen store or big box. Kmart probably has them, too. If you get one with a temperature alarm feature ( fairly standard), set it for 10° above the target. If the oven fluctuates or drifts 10° too high, the alarm will sound. This is a real plus for guaranteeing the temper does not drift off too much. Many of these thermometers have a timer, too....a double plus!
 
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Personally, I use a mid-sized toaster oven with two heating elements on top and two on bottom. I then stick an analog oven thermometer on the middle of the oven to monitor temperature. It's very rare the it reads the same as the dial, BUT it seems to remain very stable, and I don't risk mucking up my regular oven and pissing off the wife. ;)

I think I paid about $40 for mine.

I'll typically temper my 1095 blades at about 400F for 90 to 105 minutes (sometimes longer on larger blades, as they take longer to come to temp), and then I'll pull them out, dunk them in room temperature water, and stick them back in for at least another hour to and hour and a half.
 
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