Temper Question (You Know What I'm Going to Ask...)

[vanadium]

As far as I know, There is still a bit of grinding that is done post HT is done "non-cooled"… With this in mind, how much heat do you think is sunk into a factory edge?

I was just gonna bring this up. OP, even if you overheated, you only altered the temper at the edge. I'm gonna go out on a limb and say that factory knives, or any knife sharpened on a fast wheel, *typically* comes with damage to the temper at the edge. It's no big deal. Knives need to be resharpened to get to the "good steel" underneath. Now it's time for a 2009 bladeforums necro quote, which is a repetition of something I've heard from wise men over a couple decades:

I recommend doing a real good sharpening before you even use it, many times the steel at the edge had had it's temper compromised by the sharpening process and will tend to chip and roll until you give it a good sharpening to get it back to the good steel.

 

[NJBillK]

I was just gonna bring this up. OP, even if you overheated, you only altered the temper at the edge. I'm gonna go out on a limb and say that factory knives, or any knife sharpened on a fast wheel, *typically* comes with damage to the temper at the edge. It's no big deal. Knives need to be resharpened to get to the "good steel" underneath. Now it's time for a 2009 bladeforums necro quote, which is a repetition of something I've heard from wise men over a couple decades:

Bark river is (was?) known for this being an issue that they were plagued with. Kabar/Becker, and some other major brands also have had issues with this.

I know it is a big deal to keep a factory edge intact if you sell a knife, even if you use a knife for a few cuts to see if the ergos agree. That instance is more acceptable than a sharpening/stropping.

I have always liked the idea that there is potential (quite a bit of it) that a knife will get a bit better with age. I am not speaking years, but use it, see that you like it, sharpen two or three times and find that the edge can last an additional day, week or even a month (depending on the alloy and usage).

I love the exchange here, and 95% of what I will sell is unused/unsharpened. That being said, some models just fit my hand enough that I Have to use it (ZT562 & 770, Spyderco Mantra/Delica).

That being said, I need a Maxamet Mantra 1 ground to =/>.015 BTE.

 

[knarfeng]

While I am not disagreeing with your post, I am curious about a few asides. Please bear in mind that I am not privy to all of the intricacies involved with factory knife making.

As far as I know, There is still a bit of grinding that is done post HT is done "non-cooled",

Please note that I used the term "final sharpening" as opposed to "grinding".
Yes it is possible to overheat due to major grinding. But that's not the same as a few seconds on an abrasive belt to produce the final edge. The OP was not grinding. He was stropping with leather. That is not a long process if properly done.

 

[Leo3an]

Im not an expert at all, but i like watching how custom knife makers work on Youtube.

It seems they use either belt sander or buffing wheels after heat treating their knives. I dont see them checking tempurture though.. maybe they know how to tume them.

 

[chopsaki]

Hmmmmmm, I use a WSKO and have barley made the edge warm let alone hot. If stroping It is stated that lower speeds are desired. Heck I am pretty sure it says to primarily use a medium speed even when sharpening and only use the high speed for tool grinding and such. I use it for my kitchen knives and users and get super sharp edges in minutes. I’m not sure about the tempering as I have heard a lot of conflicting info, much like this thread. I haven’t felt a difference between my stone sharpens baldes vs the work sharp so I can’t say for sure.

 

[Sonnydaze]

A few seconds at 400F isn't going to change the temper.
When the knife was initially given its final sharpening in the factory, it wasn't done by hand, and the machines I have seen used for final sharpening in factories are not water cooled.
[/QUOTEI]

THIS IS GOOD INFO.

 

[Knife Outlet]

Just an overall comment. The trade off with powered sharpeners is pretty straightforward. On the plus side you gain speed and time saved, On the negative side you lose more steel because powered sharpeners remove more steel than is necessary. I recommend manual guided systems. They will get a knife as sharp as it can be and yet do no harm. As long as you have the time, guided manual systems are the way to go.

 

[jdm61]

IIRC, Murray Carter says that even with his giant water wheels, he still has to keep an eye out for very thin sections getting a bit too warm.

Roman Landes has done proper research on the subject and found how really FAST grinding damage can occur. I [a metallurgist ] will agree. don't be in a hurry do it by hand .If that is not possible then grind under running water !

 

[jdm61]

Of course, things can get painfully hot long before they reach 400F. Stick your hand in boiling water at 212F. But seriously, ladies and germs, from what I have read from Roman Landes and others, the problem is that the edge is SO thin that it heats up in a flash and you may not even see any color change, but the very apex of edge has "softened." Of course, that can be "cured" with a little work on a stone, but then what is the point of power sharpening for most people? I cringe when I see the "sharpening experts" at Bass Pro, etc. throwing sparks off of their paper wheel setup.

Fact is yes you can ruin an edge and it doesnt take 400 degrees for 1 hour. Many have done it. I have. Roman Landes has as well as many more. The apex of an edge being very thin can peak at temps well above 400 degrees and 140 degrees isn't going to be a sharp pain when you touch it. As fast as you heated the edge it will cool down. But the damage is done. If you take it slow you should be fine.

 

[Cobalt]

IIRC, Murray Carter says that even with his giant water wheels, he still has to keep an eye out for very thin sections getting a bit too warm.

Is it because the water wheel is fine grit and it takes some time to grind an edge on it?

 

[marcinek]

Please note that I used the term "final sharpening" as opposed to "grinding".
Yes it is possible to overheat due to major grinding. But that's not the same as a few seconds on an abrasive belt to produce the final edge. The OP was not grinding. He was stropping with leather. That is not a long process if properly done.

Precisely. If one is stropping and getting the blade hot, they are not understanding what stropping is. Its a last step polish or something you do after each use to maintain an edge. Its not sharpening or creating an edge. You can do it by hand in 5-10 strokes.

On a machine? Couple seconds, maybe one swipe.

 

[Alberta Ed]

I can't say I've ever encountered this problem. You would think that reputable manufacturers would be familiar with the problems of overheating the edge during final grind and take steps to prevent it. Lately I have been highly impressed with the factory edges of the last several blades I've purchased (Cold Steel, Buck and Spyderco).