Are Case 'Burning' Their Blades?

J

jamesbeat

Joined
Jul 26, 2009
Messages
314
I watched the How it's Made feature on pocket knives again today.

The Case factory is featured in the video, and it shows the production process.


Something struck me this time around.

About a minute into the video, it shows hardened blades passing through an induction heating machine to anneal the tangs of the blades.

The narrator explains that this is to make the tangs softer so that they can be adjusted as the knife is assembled.

Makes sense, so far so good.

It then shows an annealed blade, and as you might expect, the annealed area is blue where it has been heated.

Thing is, that blue area extends WELL into the cutting edge of the blade.

The example shown in the video is a small blade, and the blue area is covering about a third of the cutting edge.

Does this not mean that the cutting edge is 'burned' and will never be able to hold an edge?

I know that if I was grinding on a hardened blade and it turned that color, I would be pretty angry at myself for ruining the temper.

Am I missing something?
 
It depend on what you call burned. A blue temper was used on most all knife blades at one time. If the blade was heated to 550°F, that would cause a full blue temper. It would drop the hardness to RC55. It is still going to cut, just will need sharpening more often. What does Case claim as their edge hardness? Up until recent times pocket knives had blades in the low to mid RC50's. You could easily sharpen them with a file.
 
I've tested many Case knives, the old ones (40s'-60s') Rockwell tested in the mid to upper 40s'. The newer ones (80s' to now) tested 57-58. Knives from the 70s' seem to be in low to mid 50s'. Most all old slipjoints had soft tangs.
 
Yes, there are advantages to soft tang - it allows bending/crinking blades to fit during assembly and I guess it prevents galling on the backspring too.

That video shocked me a little though, because it's not just the tang that is annealed, it is a good portion of the blade too.

It seems very strange to have a softer portion of blade near the tang that will have diminished edge holding properties.

I was thinking of buying a Case peanut, but I'm reconsidering that now - I can only imagine what that annealing process must do to the small pen blade of a peanut.
 
Don Hanson III said:
My W2 folder blades come out of the tempering oven Blue and are 61-62 Rc. Just saying.
Click to expand...

I don't doubt it, but in that case, why aren't those Case blades tempered for their full length?

Maybe the fact that the blades themselves are on a metal surface means they don't get as hot as the overhanging tang?

I suppose the metal surface acts as a heatsink, so the tang gets a lot hotter than the blade?
 
That's one of at least a few differences between a factory made blade made by the thousands, and a custom piece made by the dozens. Does it make the knife unusable? As someone who has owned and carried a number of case knives (along with many of the rest of my family), I don't think so. Do Case knives hold an edge forever? Not even close, but they do typically take a fine edge and are easy to touch up and resharpen.

If you're looking for something that's of a better quality, fit/finish, and uses one of the better heat treaters in the country (Peter's Heat Treat), take a look at Great Eastern Cutlery. I'm not sure that they have a "peanut" pattern per say, though they have a few smaller patterns that may trip your trigger still.
 
There have been thousands upon thousands of Peanuts made and I'm thinking if Case was doing something wrong we'd know about it by now. I definitely would not let that video dissuade you from buying a Peanut(or any other Case for that matter).
 
McFeeli said:
There have been thousands upon thousands of Peanuts made and I'm thinking if Case was doing something wrong we'd know about it by now. I definitely would not let that video dissuade you from buying a Peanut(or any other Case for that matter).
Click to expand...

Agreed, Case knives have been doing it right, much longer.
 
jamesbeat said:
Yes, there are advantages to soft tang - it allows bending/crinking blades to fit during assembly and I guess it prevents galling on the backspring too.

That video shocked me a little though, because it's not just the tang that is annealed, it is a good portion of the blade too.

It seems very strange to have a softer portion of blade near the tang that will have diminished edge holding properties.

I was thinking of buying a Case peanut, but I'm reconsidering that now - I can only imagine what that annealing process must do to the small pen blade of a peanut.
Click to expand...

I wonder does short time temper to blue color /like Case do/ have same effect on hardness like temper for two hours ?
 
I've carried Case knives for at least 40 years. Only had one that I felt the blade wast too soft. It was a slimline 49 pattern made in the 50s'. The Case knives made today are much harder than the old ones.
 
".....I wonder does short time temper to blue color /like Case do/ have same effect on hardness like temper for two hours ? …"

It does not lower the hardness as much as a one or two hour temper. I dip blades in 600°F molten bluing salt and it does not seem to change performance any noticeable amount.
 
jamesbeat said:
I don't doubt it, but in that case, why aren't those Case blades tempered for their full length?

Maybe the fact that the blades themselves are on a metal surface means they don't get as hot as the overhanging tang?

I suppose the metal surface acts as a heatsink, so the tang gets a lot hotter than the blade?
Click to expand...
Case is tempering the full blades before softening the tangs.

& yes to your last two questions.
 
knife to a gunfight said:
If you're looking for something that's of a better quality, fit/finish, and uses one of the better heat treaters in the country (Peter's Heat Treat), take a look at Great Eastern Cutlery. I'm not sure that they have a "peanut" pattern per say, though they have a few smaller patterns that may trip your trigger still.
Click to expand...
Yes, By far the best production traditional knives made today!
 
You must log in or register to reply here.
Back
Top