RC hardness for hunting and utility knives.

BobbyD

BobbyD

Well-Known Member
I have two knives I am making out of 52100 .136. One will be a skinner and the other a utility every day use knife. What RC do you recommend? Lately I have been making kitchen slicers with finish edge off the grinder as thin as I can get. What edge thickness before sharpening would you recommend for these two?
 
Austenitize at 1475F-1500F (no higher!) for 10 minutes and temper at 400F 2x2 hours. This gets me right around 61 HRC. That works for all my "outdoor" knives.

Your starting edge thickness really depends on how you sharpen. I've never seen two people describe exactly the same process for convexing an edge, though I expect most are very similar. The only thing I'd say for sure is if it's too thin, you can take the edge back until it's right. If it's too thick, you get to regrind to get it thin enough. If you make up a test knife, you could take it kitchen knife thin, then test that one blade against whatever you wish to use it for, taking the edge back as needed, and you'd have a good idea how that steel and heat treatment behaves for a range of thicknesses.
 
I know I will be showing my lack of knowledge here. I would think a hunter that is also the primary skinning knife would want a FFG with a small shallow secondary bevel. A hunter that is multi-purpose you would want a somewhat thicker edge that has either a secondary bevel that would be more V shaped or apple seed shaped to handle a variety of tasks.
I may be completely wrong but logically it makes sense to me.
Looking forward to more suggestions from the hunting experienced guys. It’s been many years since I’ve hunted and skinned an animal.
 
I personally don't believe you can assign a given Rc hardness value to knife based on it's intended purpose and/or steel type. IMO it's much deeper than that, and requires considering many factors.

OK, that being said, if I were forced to choose a hardness level for 52100, it would be 58-60Rc, and the ONLY reason, without considering any other factors, is so the client/buyer/owner would be able to sharpen it. Much harder than 60Rc makes most steels/knives beyond the ability of the average knife owner sharpen themselves.
Time and again over the years, I have heard complaints from people that they hate this or that custom knife because they cannot sharpen it. That immediately tells me that the maker was either likely new, or was of the mindset that a super hard blade is "best".... it's not. I could go into a long explanation, but will save that for another time/if you'd like to know. ;)
 
EdCaffreyMS said:
I personally don't believe you can assign a given Rc hardness value to knife based on it's intended purpose and/or steel type. IMO it's much deeper than that, and requires considering many factors.

OK, that being said, if I were forced to choose a hardness level for 52100, it would be 58-60Rc, and the ONLY reason, without considering any other factors, is so the client/buyer/owner would be able to sharpen it. Much harder than 60Rc makes most steels/knives beyond the ability of the average knife owner sharpen themselves.
Time and again over the years, I have heard complaints from people that they hate this or that custom knife because they cannot sharpen it. That immediately tells me that the maker was either likely new, or was of the mindset that a super hard blade is "best".... it's not. I could go into a long explanation, but will save that for another time/if you'd like to know. ;)
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I would certainly like to know. Can't have too much good information.
 
Not having ever used 52100, I'll stay away from that question. I am an avid hunter and like a smooth cutter that easily cuts hide and muscle. So on my hunting knives I grind the edge to .010 before sharpening. On a Skinner you don't want a scary sharp knife, if it's to sharp you end up cutting through hide, and meat far too easily. Personally I'd leave the edge around .015 or even .020.
 
EdCaffreyMS said:
I personally don't believe you can assign a given Rc hardness value to knife based on it's intended purpose and/or steel type. IMO it's much deeper than that, and requires considering many factors.

OK, that being said, if I were forced to choose a hardness level for 52100, it would be 58-60Rc, and the ONLY reason, without considering any other factors, is so the client/buyer/owner would be able to sharpen it. Much harder than 60Rc makes most steels/knives beyond the ability of the average knife owner sharpen themselves.
Time and again over the years, I have heard complaints from people that they hate this or that custom knife because they cannot sharpen it. That immediately tells me that the maker was either likely new, or was of the mindset that a super hard blade is "best".... it's not. I could go into a long explanation, but will save that for another time/if you'd like to know. ;)
Click to expand...
I'd be interested knowing more about 52100 at the lower hardness for exactly the reason you stated. I usually switch steels. Feel free to DM if you don't want to discuss in this thread.
 
EdCaffreyMS said:
Much harder than 60Rc makes most steels/knives beyond the ability of the average knife owner sharpen themselves.
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Until lately I have always used around 60 Rc (even 59Rc) for my knives. Reason, anything more and it was too darn hard to sharpen - with the tools and knowledge I had back then. I remember back in the '80s 'n 90s I really liked my Buck lockback pocket knives, EXCEPT for how hard to blade was, and they were only around 60Rc. I could take the normal high carbon steel knife blade and sharpen just fine, and pop hairs with no problem. That darn Buck was MUCH more difficult to sharpen, and I broke too many blades.... yea, I was really rough on my EDC knives.

I've just finished two AEB-L chef knives with 62Rc and a 63Rc to try for myself to see how they work.
 
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I have not a lot of experience with 52100 but let me make a comment on hardness. Yes, you can make a blade that will seem to hold an edge for ever, and I believe that 52100 has that reputation, but the flip side of that is that the blade will seem to take for ever to put an edge back on it and it might need something like a diamond stone.

Give some consideration to a steel that doesn't harden to such a high HRc. It's won't hold an edge as long but you can put an edge back on it quickly with a Indian stone or a piece of wet hard sandstone.

Doug
 
Kevin just posted a thread over on the heat treating section that address things we are talking about here. I am a new maker and trying to learn not only how to make a knife but also the attributes of a given knife. I do know steel, heat treat, edge geometry, which includes not only the sharpened part but also what behind that edge ,thickness of steel and the list goes on. So much more to being a good knife maker then making the physical knife. Sometimes my heard hurts lol
 
I don't know whether Kevin is reading my mind... or has "the borrowers" looking through my notebook at night..... but he saved me a ton of typing with his thread on the heat treat forum. What he calls "the triangle" is something that I've been teaching to students for years, and what I was going to attempt to explain here..... but no need now. :)
 
All great info. But just to play devil’s advocate... Back when diamond stones were crazy expensive, having a blade too hard to sharpen was a big problem for almost everyone. Nowadays they are easily found, maybe even more commonly than whetstones. I keep an inexpensive fine/extra fine compound diamond stone in my bag that will sharpen anything in minutes.

I honestly don’t hear “I can’t sharpen this knife” too much these past few years. I do get customers who come to me because they want a knife with much better edge retention than what is generally offered in production knives. Now, it’s entirely possible that I get an unusually high percentage of knife nerds who like to collect the boutique knives. So, my devils advocate position is probably skewed towards that demographic.

In the bigger picture, a lot of customers just aren’t very good at sharpening, which is why all of my knives come with free sharpening for life. (Which also gives me the opportunity to freshen up the knife and send it back pretty. This has led to a lot of repeat customers. Keep in mind that I’m a part-timer, so this doesn’t cost me a lot of lost production time.)
 
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