and here is where we disagree.
When grinding on any metal, heat transfer to your hand is not immediate and is not direct. The thickness of the blade and it's size asre all variables in heat dispersion within the metal. The thinner the metal the higher the heat will be. In other words, when you are grinding on a piece of steel, just because you cannot feel the high heat at your hands doesn't mean that the little section you were grinding on didn't just flash to over 400 degrees.
Agreed! As noted in my past post... this is the reason why at least one digit is kept in direct contact of the thinnest area being ground at all times.
metal is a good conductor of heat, but not a great one, that is why there are better ways to conduct heat out of areas where convection is not possible and radiation is useless.
Metal is a good conductor of heat. That in conjunction with frequent cold water dipping will do a good job of keeping things cool. It only takes a few seconds for water to disperse most of the heat.
how hot does your hand feel before you stop grinding. I did a little experiment with a cheap blade and sanded it's edge on the belt sander and within 2 minutes of several passes on each side of the blade the knife was very hot to the touch. If I stop to cool it off and start again, I will be there all day. So do I go a little further until it is too hot to touch, like maybe 200 degrees and then stop giving me several extra minutes. However, this two inch wide blade is that hot at the spine can you even guess how hot it must be at it's very thin edge. I can tell you that twice that hot might just be conservative. this is why Busse cannot warranty it once it has been severly modified, because there is a good chance you have just added another temper cycle and reduced it's hardness by a couple of points.
Of course it would take forever if your hot blade was left to air cool. Cool water would have taken only seconds to pull out most of the heat. The hottest area of the blade is the portion being ground because that is where most friction is generated. If you focus your grinding on a area near the spine or middle of the blade that would be the area that is the hottest and not the edge. 2 minutes is an awfully long long long time to grind on a heat treated blade without cooling. I cool the blade after every single pass and at max 2 passes. Each pass takes approximately 3-10 seconds depending on the length of blade and area being worked on. I stop grinding and dip in cool water as soon as the passes are done or when I feel the thinnest area being ground gets warm to touch. Whichever comes first.
The intro of stress risers might be another reason in some cases.
Now if you can grind that edge under cold water then you are fine.
The files are 62rc and are harder than INFI at 59-60rc. However, you will be going through lots of files because all of the teeth would be ruined quick style. You are much better off with very coarse sandpaper or extra coarse diamond hones.
WOOF!