Knife School: Sharpening Philosophies
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- čas přidán 23. 07. 2024
- In this video, I explore and discuss some of my fundamental sharpening philosophies. Please understand, there are many opinions and ideas about how and why to sharpen a knife. I'm merely trying to explain mine, based on 30+ years of making steel things sharp and keeping them sharp. Please excuse the poorly drawn diagrams -- it's been a few years since drafting class :).
These are just some things you need to know before you send your knives to me for sharpening. If they make sense, and you see some value in what I have to offer, I'll be happy to help. If you disagree, no problem. Please be kind and respectful in the comments section. Grace and Peace, guys :) - Věda a technologie
Good video Rob. I completely agree with you on edge angles but I disagree on edge finish. I get that you prefer a polished edge and thats fine but from my experience (at least on higher carbide steels vg10, 154cm and up) a coarse edge performs better. Amd i mean a coarse edge, not a factory edge, a lof of people think thats how a coarse edge looks, feels and acts like and its way off since its usually overheated steel thats been buffed and it will bend and flop around until you get to good steel and then its cuts great. Polished edges perform better at push cuts and chopping since it's more refined (if you look under a microscope, it's still toothy, just the teeth are smaller/closer together) but for slicing and most of edc tasks(in a folder) require slicing they lack the agression needed and have much less wear resistance. Why do you think most guys use a coarse edge when cutting rope/cardboard? its not because they cant do a polished edge (Ankerson used the 6000 edge at one point), its because you get better/more cutting ability from a coarser edge. And you can get a really sharp "toothy" edge that will shave good, push cut phonebook paper and have great slicing ability. but everyone has a preference and as long as it works for you, thats whats most important.
very useful thoughts
As always, one more great video. Very informative. Thank you for sharing.
Rob wish I would have been a follower from the beginning. I think all my questions will be answered shortly as I go through these older videos. Extremely instructional. Thanks
Fantastic lesson and video. Ya know, I read somewhere that although D2 is a tough steel for edge retention, it can only get so sharp. ( I don't know if it's true, but read on.) It said the reason is D2 is a "toothy" steel by nature, and no matter how much ya work on it, those little teeth keep re-appearing & that's why they don't use D2 for surgical instruments. But the advantage of D2 is for paper, cardboard & wood material. The article claimed that D2 is used on almost all cutting tools found in paper mills, because the micro-sawing action cuts those types of materials better, yet those teeth hold up to wood/paper products longer. If you have the time Rob, what's your thoughts on that? I'm assuming that the natural "teeth" they were talking about in D2, has more structural integrity, than the typical raggedy teeth of terrible factory edges found on knives of any type steel. ????????? Thanks for this video and your time, if possible, for my questions on D2.
Great video❗️
Obviously, you understand knife edges very well‼️
I’ll probably send you some work soon.
I’ve seen your work on videos a few times. They are always interesting videos.
No, the word is sharp haha. I wish I would have discovered your site back then. I’m going to have to delve back into your older videos. I’ve missed so much coming in the last couple years!!! You were such the teacher that I so needed.
Do you have any experience with Slack Belt for rolled edge blades? For instance, Trail Master features the rolled edge design (the only knife from Cold Steel with rolled edge).
Also, you can get diamond rods from Spyderco (for the Sharpmaker) to shave more steel (they sell them seperatly along with finer grit ceramic rods ((compared to ceramic rods that came with he sharpmaker)) ).
In your opinion, how are the factory edges on Spydercos? Are they as toothy as most factory edges? I would put mirror finishes on all my factory edges, but I just haven't because I felt like it wasn't necessary. I was wondering whether it was necessary to do it to all my spydercos?
Hmm, I've always sharpended my blades with just the primary bevel but recently sharpened both a PM2 in S30V and a Stretch in ZDP189 using the Compound bevel concept. I've become a believer! Even just initial sharpness is noticeably better.
Good explanation, Rob, but do you have a video explaining HOW to effect a micro-bevel and what types of blades you would consider eligible candidates for such edge geometry?
This video was very helpful and answered many questions. Thanks.
Great summary video about advantages of micro-bevel!
smooth edge is good for hatchets, razors, machetes, wood work tools\knives and as long as you can push cut through the material. if you have to cut things like plastic, industrial grade straps or zip ties, blister packs, rope, someone is going to insult you and say your knife is dull... i think 600-1000 grit on the micro bevel is ultimate for a pocket knife. Still shaves hair and have some teeth for harder materials.
Hi ApostleP,
With a micro bevel, how wide can you go before you experience issues cutting? For arguments sake, if I have my secondary bevels set 20dps, how wide would you say I could go on the micro bevel before running into issues? 25? 30? Have you done any tests this?
Thanks and Merry Christmas!
For edges that do look like the Burger King crown, how do you prevent from folding those teeth over while sharpening? If using the Sharpmaker, would I start by running the blade up the stone rather than down?
so how do I solve the toothy edge problem right away
just purchased some CPM S125V .. do you make knives and or if I get one made can you polish it...?
Thanks your video. two things i thought of . i always wondered why someone would send a new knife to you now i get it they want to start the life of their knife with a polished edge (also explains a lot of frustration with the results i have been getting.)
2nd is a question i notice some people (spyderco sharpmaker) use the 30 degree settings to get a very sharp point . understand this can give that point but it wont last also make honing the blade again harder with longer areas to sharpen ie defeat the purpose of a bevel. here the question on knives one has for light use ie gentelman knives would it make sense because max sharp is what you are looking for and due to light use mantaining would less severe or is this a bad idea for other reasons.
30 degree is for knives that are more focused on cutting and slicing than for survival/tactical/utility knives (although some people prefer the 30 over 40). I suppose it can also be used to hone the secondary bevel as well.
(please see my other comment first) I forgot to point out ( which I'm pretty sure you already know, but maybe some of the viewers may not ) in my other comment about D2 steel and paper mills/factories, that they are cutting a heck of a dense stack of paper at once. I would assume those cutting tools would resemble a big machete type blade, attached at one end with a pivot on a cutting table. A handle on the other end, that a worker grabs and pulls down and sort of "chops" the paper stack. It would still be somewhat of a pull cut due to the angle of the blade coming down, and not really a straight on push cut. I'm really curious to know what your personal & professional experiences are with sharpening, applications & performance of D2. Yeah, that article really got me to thinkin'. Thanks again Brother Rob!!!
How do you use the strop?
Interesting points, but... is taking off extra material really a big deal for most people? Does their knife disappear after 10 years of too much sharpening, or something? And don't polished edges also fold over and require a honing steel periodically too (especially kitchen knives)?
Would you consider a convex edge a compound grind with an infinite microbevel?
Hello ApostleP,
Very nice video! Personally, as a professional sharpener I go for the convex edge, but I like your approach and I love your explanation. Good of you to share your passion with the world.
+JoeyJoeJoe Jr Shabadoo technically speaking putting a micro bevel on a v grind is somewhat a convex edge. but as for a straight convex edge goes with a lansky edge pro or wicked edge, then no they cannot do a convex grind
The KME has a rod that convexes. It's trickier to do but it can do it.
The other option is to go over the knife a few times at steeper and steeper angles to create a series of compound bevels and then stropping with a compound. I think that this is even tricker though.
This kind of video is awesome. Thanks. Plz keep it up
I agree but I use 20 and 25 degrees since you can still get a hair popping edge but it is a little sturdier
Thanks for the support, Dustyn! I was hoping it would help some guys understand some terminology and concepts.
No problem, buddy :). I'm glad to help.
Great vid. How long does it take you to sharpen a blade? Like a well used blade vs a completely shot edge? I keep my knifes sharp but not razor sharp. I think I lose patients and rush my finer stones.
Yes, they do look wicked, don't they! I think 37 degrees inclusive will do just fine without a microbevel. It's kind of a good "in between angle," thin enough to slice but strong enough to hold up. I do the approach bevel / micro bevel for ease of maintenance and touch-up sharpening, as well as cutting performance. Most of the guys I sharpen for have Sharpmakers, and they can bring their knives right back with a few strokes on the 40 degree side with the fine rods for a long time.
That's a great question, with a complicated answer, Zechs. But on an average 3 1/2" folder that needs to be completely reprofiled, sharpened and stropped, it's about a 2-hour process for me. So, if I charge $20 to do it, I'm slightly more highly paid than the girl who makes your Quarter Pounder :)
Hmm... never really thought about a toothy edge folding over like that. But it makes sense. I like a polished edge too, but more just because I like how it looks. But you know, after I re-profiled one of my XM-18s to 37* inclusive (no micro bevel...yet. :)) & polished the edge it definitely has held it's edge much better, so you are probably onto something. Great vid!!!
Makes perfect sense . cheers !
Would they be... tactical spoons?
Which grit you would consider toothy edge for micro-bevel? Is 1000 or 1500 considered toothy? Or you do as far as same level of polishing and secondary bevel?
Serg Melikyan I finish to 2300 grit, then strop to 0.5 micron on most steels, but if you want a bit more tooth, you could stop at 1000 on the stones and just give it a quick strop at 2.0 microns to remove any burr and call it done.
TheApostleP thank you so much for your reply and your videos! I recently decided to take on sharpening my knifes and this evening I am watching all your related videos. So much information! Thank you for sharing this with us!
Thanks the was the general ball park I was looking for.
Is a micro bevel generally 10 degrees different from the secondary bevel ?
Generally 3-5 degrees per side.
The Sharpmaker is a great tool for touch-ups and honing, I use mine routinely to maintain that 40-degree micro-bevel. But I learned years ago that the 30-degree side of the unit is pretty much worthless for re-profiling. The "coarse" rods aren't coarse enough to really remove any material, and they load up quickly with steel, rendering them useless. Now, I have seen Crocket20 tape some 120-grit sandpaper to them for re-profiling, which does work, but there are better tools for the job.
Thanks, Chubby! Hope you enjoy that Scallion :)
Just curious. How do" you" sharpen DENDRITIC STEEL ?
Thanks.
I don't believe I've ever had dendritic steel at my bench. It's a pretty esoteric process in which steel is cast, rather than smelted, in such a way as to produce "dendrites", or fern-like carbide structures, which produce a structurally toothy edge. David Boye popularized (if you can call it that) the use of dendritic steel. Only he and a very few other makers, who all use his blanks, currently work in dendritic steel. My limited knowledge of this steel would probably lead me to take the cutting edge to a less polished edge than I currently do on most steels.
+TheApostleP I think the point is that you are supposed to polish the edge, then the specific way the steel wears causes the edge to transition from a fine cutting edge to one which has more tooth without having much sacrifice in cutting performance during the transitional period while the knife is being used.
Also the steel he uses is something like 440c if I recall and it is cast, which is easy to sharpen on stones that don't leave a consistent scratch pattern (natural Arkansas stones for instance) and can get very sharp edges with a variance in teeth at the edge because the structure of the stone literally cuts the steel instead of abrades it, I'd wager when an edge such as this wears in with the dendritic structure in the steel the results would be optimal.
even the polished blade has micro teeth that still bend over they are just smaller
Stupid noob lansky user question...do you do the micro edge bevel first or second? Shallow then steep or steep then shallow?
Great video, I totally agree a polished edge will last longer and be easier to sharpen.
Ah... a sharpening Jedi you will soon become, young Skywalker :)
Thank you Obi-Wan!
good discussion buddy, if it ain't sharp then we might as well be carrying spoons.
Even polished edges have teeth and slicing aggression. If you're polished edge doesn't bite your skin when you feel it, you've rounded the apex.
Jarl Anarch That's true. I was mainly trying to contrast the difference between toothy and polished, without getting into a debate with the "toothy guys." Now you've started it!
TheApostleP I figured you knew as much, I was just informing the other folks that may not have known :)