Sharpening Progression 103: Advanced Concepts (Too Much for a 102)

This was going to be a 102 but it got WAY into the weeds so I decided to make an intermediate video between this and the 101.
Abrasives
1) Alumina
2) Silicone Carbide (SiC)
3) Diamond Plate
4) Diamond Resin
Binders
1) Soft: Usually soaking. Faster at removing material due to breaking down. Needs flattening and has best feedback. Concentration of abrasives varies widely. Generates a slurry that gives an even cloudy finish.
Examples: King KDS 1K, Suehiro Cerax, King Neo, Cheap amazon stones
2) Hard: Slower cutting but handle handle harder steels better. Usually splash-and-go. Tend to polish more for their grit rating compared to softer, soaking stones. Will load up some.
Examples: Naniwa Pro/Chosera, Nanohone, Shapton Pro and Glass
3)Plates: Abrasive is added directly to surface. No flattening and leave very deep scratches.
Examples: DMT diamond plates, Worksharp diamond products, Sandpaper
4) Resin or Metal: Slowest cutting and will load up due to binder not breaking down. Can't absorb water so they are splash-and- go. Don't dish and leave a nice satin finish. Often abrasive is diamond.
Examples: Venev resin bonded diamond, Naniwa resin bonded diamond
Steel
1) HRc: High hardness requires high concentration of abrasives first then harder binders hold up a little better.
2) Carbides: Higher carbide volumes need higher abrasive concentration. Type of carbides will decide what abrasives to use. High chromium carbides alumina and SiC work with SiC being slightly better. High vanadium carbides requires diamonds to shape because VC is harder than either alumina or SiC.
Desired Results
1) Choose abrasive and binder type depending on the steel chemistry, heat treat and end use. Choose final grit to match your use and then backtrack to your starting grit using the rules of thumb in the 101 video.

[@billylallen2662]

Great educational video, thank you for taking the time to explain this to people like me who are starting out.

[@EngineersPerspective701]

Appreciate the comment!

[@knickly]

Thanks you for sharing! Fun fact: magnesia bond is basically magnesium oxychloride cement.

[@EngineersPerspective701]

Appreciate the tidbit!

[@turing2376]

Loaded this one up on the TV to watch! Enjoyed. Made sense to me. Confirmed mostly how I have been thinking about it and seemed in line with my sharpening experience thus far. However, I have been reading science of sharp articles recently which are interesting but are muddying the waters for me a bit. Although they are based on studies of razors it is making me question things a bit. I need to reread some of those articles to be sure I am interpreting correctly, though some of the articles themselves pose further questions, leaving more to be desired...more studies needed maybe. They do make me wonder about possible subtle differences with knife sharpening or else that some of my views are not entirely representative of what is actually going on, maybe a little of both likely I guess, not sure. 🤔 Request - Stropping, stropping media and compounds, and effects on edge apex and bevel could be 104:advanced #2...just throwing it out there 🙂

[@turing2376]

BTW, want to say again, good job on these videos. I have gathered a lot of info from various sources, youtube mostly. A lot of different ideas/info bouncing around. You seem to pull it all together to help make the complete picture. Thanks!

[@EngineersPerspective701]

Honestly science of sharp also raised more questions than it answered! Mostly on what exactly is happening with the burr. After screwing around with the ideas that were raised I’m still confident with ideas and techniques that I’ve been using for the most part but don’t feel like I have everything “answered” yet. Really appreciate the words and I’m glad that it’s coming together into a useful product!

[@s241914]

At first I thought it was strange that you classified this as advanced concepts. I think a lot of people are afraid of making sharpening videos too in depth because they think it is overly advanced for the general public to care, or they are so advanced themselves that they assume everyone watching their videos knows this information already. Because of that, it's hard to find videos like this. I'm a beginner, and I've been looking for this type of information for a long time now. I understand how sharpening works on a basic level as I don't think it's that hard of a concept to grasp. It seems like almost every video on sharpening repeats the same old "create an apex, remove the burr" instructions. And similarly, your 101 and 102 video were helpful but didn't quite give me the all encompassing big picture as I had hoped. I was on the hunt for a preliminary understanding of all variables and what their purposes were. Tangible categories are something that should be required knowledge for anyone learning to sharpen since as a beginner, you quickly wonder what all the types of abrasives are and what the differences are between them. And you start to form other questions like which steel and what situation should you use a certain abrasive? Does width of a stone matter? Does the type of wood for a stropping block matter? Can you use something other than wood? Etc. So thank you for making this video. I hope you continue this series as I've found it very instructive, and reading your replies to others' comments, it seems you have the level of knowledge that I wish to attain regarding sharpening. And I wanted to say don't be afraid to get in depth! I know in 102 you stated that your first take was a bit more advanced than you liked and so you saved that for 103, but don't underestimate your audience! We aren't subscribed to "An ENGINEER'S Perspective" for nothing. This was exactly the type of info I wanted! Thanks again.

[@EngineersPerspective701]

I’m so humbled reading responses like this! I really appreciate the feedback! There is definitely more to be said for a 104 because I didn’t quite drive home all the points I wanted with this one. Thank you again!

[@danmichell7516]

id like to see finer break ups of your advanced ideas 103 104 105 ...

[@EngineersPerspective701]

I appreciate the interest! I had meant to make some more at the time but kind of lost motivation for it. Maybe one day!

[@cranmerparish1276]

If you're sharpening a high vanadium carbide knife, say s90v. Is sharpening micron size a factor that matters almost as much as the type of stone being used? Reason being, the carbides are 1-2 micron, if I'm sharpening with a much higher micron stone, say a 2000 grit/10 micron I'm really not interacting with the apex at the 1-2 micron level. I would think, diamonds are not needed to cut the vanadium unless my sharpening is much closer to the size of the vanadium carbide. Any alumina stone can cut the iron that makes up the majority of the steel. Thoughts?

[@EngineersPerspective701]

I see your thought but it's not really how it all shakes out. A 10um diamond abrasive is definitely cutting 1-2um carbides at the apex. It is leaving a coarser apex with a greater radius/width but shaping the carbides absolutely. What happens when you use non-super abrasives on high VC steels is they will cause the carbides to stress fracture at the apex but more so right below the apex causing you to have a weak edge that will fail. Any carbides that don't fracture at the apex tend to get burnished and/or rounded over, reducing their bite. I have seen reports on using low girt alumina stones to shape the apex and then around the 6um mark, switch to diamond to do the final shaping of the apex and grind it down enough to remove the sub-apex fractured carbides. Science of sharp has a bunch of really good articles on this topic that recently came out. Look for articles called "Carbides in...." S110V, 15V, K390 etc. scienceofsharp.com/

[@cranmerparish1276]

Thank you for your response to my question and that's a great article you've linked to. Have you been able to find any comprehensive list separating the steels that should be sharpened with diamonds/CBN versus softer abrasives? I really enjoy your channel.

[@EngineersPerspective701]

@@cranmerparish1276 what it really comes down to is how much Vanadium Carbide is formed and remains after tempering. Super rough number to judge by is 6-8% VC by volume. Realistically just use diamonds whenever it’s not a basic steel! Note that is not the same as the amount of Vanadium that starts out in the chemistry! Steel Nerds has a lot of these values included in his articles or you can buy his book which as tons of photos and tables with this info. Hope that helps!