Couple quench and temper questions.

[Wade Jones]

This will be my first go around, and I've decided to try and do the quench and temper myself. I've been reading all I can, and I think I have a pretty good grasp of it.

1084 steel.
Not sure how I'm going to heat it up yet. I may build a small fire brick/propane "forge", or I may just heat it in my fire pit. Either way I'll do the magnet test I suppose.
Planning to do a full quench, nothing fancy, in a large ammo can full of oil. I will attempt to heat the oil to as close to 140F as I feel comfortable doing.
Then I'll put the hardened blade in the kitchen oven at 400-450F for 2 hours to temper.

Questions:
1: I have a variety of synthetic fluids left over from my race car parts retail days. Does using sythetics rather than dinosaur bones have any effect, positive or negative, on the quench? Also, is it preferable to use new oil, or oil from the crankcase?
2: How long do I leave the blade in the quench tank?
3: Can I temper in my electric kitchen oven? If so, is there any adjusments I need to make to time and temp?
4: Does my plan seem sound? Am I forgetting anything?


Thanks for any help on this. I've been reading so much about this over the last couple of weeks, that my brain is beginning to hurt. And I want to make sure I get all my ducks in a row for this first attempt.

Many thanks!
-Wade

 

[silver_pilate]

I might suggest something along the lines of canola or olive oil if you're going to use something off the shelf. Motor oil tends to flair up during the quench and makes a good bit of nasty smoke. I'd use clean oil regardless, probably staying away from synthetics, and make sure you agitate the blade until bubbles stop forming (that's another benefit with vegitable oil...you can see your blade). Agitate by moving the blade either edge to spine or tip to butt (not side to side).

I agitate until the oil stops forming bubbles, and then I leave the blade in the quench until it has reached the temperature of the oil. From there, I pull it out and let it cool undisturbed to room temperature.

Make sure you let the blade cool all the way to room temperatuer before tempering. I do use my kitchen oven, however, I verify the temperature with two seperate thermometers placed in the area of where the knife will be. Tyipcally, oven thermostats can be off by quite a bit at different temps (mine is about 25 degrees off at 400F. I also turn the oven on and let it stabilize in temperature for an hour or so before tempering. This reduces large temperature swings. I also place a cookie sheet on the oven tray above the heating elements to help reduce radiant heating effects when the elements turn on. I know some people use a cooking sheet or pan full of clean sand to act to stabilize the temperature as well. A large brick may do the same for you.

--nathan

 

[69_knives]

I would start lower on the tempering temperatures. start with the oven set at 325. I temper 1095 at 385 - 390F and probably wouldn't go higher than 375-380 for 1084.

I also higly recommend some type of muffle, extra mass or air cushioning to level out the ups and downs in the oven. The first place that will be effected by the high swing will be the thinnest part of the blade- the edge. http://www.bladeforums.com/forums/showthread.php?t=652704&highlight=tempering+muffle Buy a $10.00 multimeter with thermocouple to measure the temps in your muffle.

 

[mete]

If you use a kitchen oven to temper make sure you remove all the oil first especially if you have a wife !

 

[GHEzell]

If you use a kitchen oven to temper make sure you remove all the oil first especially if you have a wife !

Good advise... also, consider buying a good oven thermometer, ovens are not that accurate, having a good thermometer lets you dial in the exact temperature you need.

My oven is off by more than 100 degrees!