Coffee thoughts... M390

[R.Russell]

So, we have an American production knife maker offering a knife with an HRC of 58-61. Is that considered acceptable quality control these days?

I wouldn't want to pay for a super steel knife and get one of the ones at 58. 58, 59, 60, 61... We're talking over $300 here.

My mind drifted to a recent film I saw where a Japanese cutlery producer had an entire hallway of blades that did not make spec. That wasn't acceptable to them. The fails were considered a cost of doing business..

In general we are spoiled with good quality in the USA but I'm feeling a little grumpy today.

 

[Monofletch]

I wonder how many makers even test their blades HRC. What good is Magnacut at 57-58?

 

[R.Russell]

I wonder how many makers even test their blades HRC. What good is Magnacut at 57-58?

Yeah, man!

 

[oldmanwilly]

For most knives and end users, anything between 58 and 61 is probably fine and average users are unlikely to notice any difference at all. But you would like to think a knife in the $300+ range would be a little more tightly controlled. What is the knife intended to be used for? HRC might not matter much on an OTF with a double edged dagger grind (so long as it isn't too brittle), whereas a hunting knife will genuinely benefit from the higher hardness.

 

[R.Russell]

For most knives and end users, anything between 58 and 61 is probably fine and average users are unlikely to notice any difference at all. But you would like to think a knife in the $300+ range would be a little more tightly controlled. What is the knife intended to be used for? HRC might not matter much on an OTF with a double edged dagger grind (so long as it isn't too brittle), whereas a hunting knife will genuinely benefit from the higher hardness.

It's a folding pocket knife, it's for cutting. If I'm buying M390 I want a proper heat treat at above 60 to get the most out of the steel. Maybe I'm being unreasonable.

 

[oldmanwilly]

I don't think you're being unreasonable, just curious to know which knife you're talking about. I think the obvious answer here is to just buy something else and hope the manufacturer gets the message.

 

[R.Russell]

I don't think you're being unreasonable, just curious to know which knife you're talking about. I think the obvious answer here is to just buy something else and hope the manufacturer gets the message.

Rather not name the maker, it seems to be an industry thing but I'm used to seeing 2 or 3 HRC points not 4...

 

[oldmanwilly]

I did a quick search of folding knives in M390 with a described RC of 58-61, made in the USA by an American brand, and offered for $300.00+. There were a few results and I believe I have narrowed it down to a specific model by a specific brand. If my suspicions are correct, I have had a negative experience with the same brand (no need to be re-hashed here) and am not surprised by the current conduct. At the very least, I appreciate the honesty of their marketing.

 

[scorpnsnake]

Just the thought of a less than optimal HT for that kind of money put butterflies in my stomach. lol

 

[Flatsman007]

I thinks you should just find a different knife or brand instead of concerning yourself with something you deem inferior. It’s a waste of your time and energy.

 

[SwissHeritageCo]

Same goes for all steels living up to their potential really. I will say, MBK's 14c28n has been pretty glorious precisely because they ran it harder than usual.

 

[Tsujigiri]

There's a lot more that goes into these hardness values than setting a goal and meeting it. Most knifemakers don't have the equipment to heat treat large batches of blades themselves, so they have to send them out to companies that don't specialize in knives and hope they get it right. There are a bunch of variables that are difficult to account for, like where the blades are located in the furnace, what coatings get applied to the blade, how the blanks are roughed, etc.

Different knife companies will then publish wildly different hardness ranges depending on how conservatively they want to advertise, and how deep their understanding of heat treatment is. So it's often the case that two knife brands will produce about the same results, but one will post a broader hardness range because they better understand the effects these variables have. On the flip side, Medford claims to hold a tolerance of one tenth on his Haas mills (this is pretty amusing to any experienced machinist).

 

[knarfeng]

So, we have an American production knife maker offering a knife with an HRC of 58-61. Is that considered acceptable quality control these days?

I wouldn't want to pay for a super steel knife and get one of the ones at 58. 58, 59, 60, 61... We're talking over $300 here.

My mind drifted to a recent film I saw where a Japanese cutlery producer had an entire hallway of blades that did not make spec. That wasn't acceptable to them. The fails were considered a cost of doing business..

In general we are spoiled with good quality in the USA but I'm feeling a little grumpy today.

The best that any producer can do is provide a hardness spec +/- 1 if he is going to be absolutely accurate in his hardness citation.
Because of the way hardness testers are calibrated, there is a possible difference between two different hardness testers calibrated to two different official hardness standards of +/- 1.

So in this case, the maker is stating that his hardness spec is 59-60 as measured on his own tester. If measured on a different tester, the reading could be between 58 and 61. That seems tight enough to me.

 

[Twindog]

A knife steel heat treated to 58 Rc is not necessarily worse than one heat treated to 60 Rc. Rc hardness is not a measure of heat treat quality; it's a measure of hardness.

In the same alloy, softer steels tend to be tougher. less likely to chip or break. Harder steels tend to be more wear resistant, less likely to roll. Depending on how you use your knife, you might be better off with 58 Rc or 60 Rc.

 

[Monofletch]

I have found that most knives need a good sharpening too remove that burnt edge before they really start to perform well.

 

[rlewpolar]

Been on a Two Sun knife binge lately and many of the ones I’ve bought are M390. Many of their M390 knives test between 60 and 62 HRC and for what I paid for them (most under $100 with full titanium handles), I am extremely happy. A $300 domestic knife should be able to do at least what the Chinese are doing with their $100 knives. It’s not asking too much IMO

 

[R.Russell]

A knife steel heat treated to 58 Rc is not necessarily worse than one heat treated to 60 Rc. Rc hardness is not a measure of heat treat quality; it's a measure of hardness.

In the same alloy, softer steels tend to be tougher. less likely to chip or break. Harder steels tend to be more wear resistant, less likely to roll. Depending on how you use your knife, you might be better off with 58 Rc or 60 Rc.

I don't think we're debating that. But heat treat optimization on a specific steel is part of what you're paying for in a premium knife purchase. If I buy a knife in Rex-121 I don't want the maker under-heat treating to make the steel more forgiving, I'm buying that steel for its wear resistance. To put it more succinctly, if a maker is targeting 60hrc and they do their heat treat in house, you buy a knife that's 58 and I get one that's 62--- My blade's heat treat is 8% higher than yours.
They're making a blade and putting a handle on it, it's not building a car.

If we were I might ask "why do my breaks work 8% better than yours?"

IMO a smaller target range should be achieved with a production knife.

 

[R.Russell]

To put things in perspective, Carothers makes batches of lets say 20 -100 knives and they list an exact HRC or a range of 1 point from what I've seen.

I'm guessing this is a very modest operation compared to the larger knife companies.

How is a small shop getting more consistent results? Maybe they put more effort into the product and QC than into advertising, etc... ????

 

[Twindog]

I don't think we're debating that. But heat treat optimization on a specific steel is part of what you're paying for in a premium knife purchase. If I buy a knife in Rex-121 I don't want the maker under-heat treating to make the steel more forgiving, I'm buying that steel for its wear resistance. To put it more succinctly, if a maker is targeting 60hrc and they do their heat treat in house, you buy a knife that's 58 and I get one that's 62--- My blade's heat treat is 8% higher than yours.
They're making a blade and putting a handle on it, it's not building a car.

If we were I might ask "why do my breaks work 8% better than yours?"

IMO a smaller target range should be achieved with a production knife.

Your OP is about production knives with a range of hardness projections. I don't know of any production companies that promise an exact hardness. You can order a custom knife and get an exact hardness, but it will have to be tested and you'll pay more.

I have a Rex 121 at 70 Rc. It's very thin with an edge thickness of 0.007 inches. It's a dedicated knife to opening packages. It's a laser. But I would not use it as an EDC. And I bought the knife from a custom maker who measured and told me all the specs up front.

If you think hardness variances are large on production knives, you should actually look at the variances of edge thickness and edge angles -- and keenness. And you should look at differences in grain size and the presence of inclusions.

If you buy a knife with a hardness range of 58-61, then you know the range of uncertainty. If you need more precision, you can purchase that precision. But a knife at 58 Rc is not necessarily more poorly heat treated than one at 61 Rc.

 

[AntDog]

You wouldn’t notice anyway.