Advantages and disadvantages of different sharpening techniques
- This topic has 63 replies, 9 voices, and was last updated 11/20/2018 at 12:14 pm by
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I was doing a bit of reading of Roman Landes work (German) on the effects of sharpening on fine edges (our domain). He gets into the heat and stress applied to an edge during grinding and the importance of a wet setup. This is very relevant to belt grinding and I wonder what effects are happening while using WEPS which may impact edge retention.
He talks about excess heat at the micro scale which is both unobservable and unmeasureable but certainly exists. It would be interesting to run some edge retention tests after using the WEPS upside down while the knife is immersed in a bucket of water – LOL.
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TC you bring up something I’ve been wondering about. Many knives I come across have those pesky little chips. As we remove them by taking off quite a bit of steel (relatively speaking) we start going into thicker parts of the blade which long term will require thinning of the blade. Is it possible to do thinning with the WEPS ?
I have thinned the profile of several knives, that is the shoulder behind/above the edge and higher, still, above the shoulder. Some issued I ran into: 1) it’s hard to achieve an angle that low with the WE System, without hitting the jaws and/or vice. 2) It’s a lot of steel to try to remove by a method intended to remove small amounts of steel. (Especially if it’s a very hard steel). 3) It’s hard to remove that amount of steel and maintain the smooth, consistent and uniform shape of the knife’s original grind. My impression, to truly thin the grind of a knife is a regrind requiring the use of a proper tool like a belt grinder or a long slow process by free hand on a large flat stone.
The next best thing I found was to profile the knife to as narrow a bevel angle as I could accomplish with the WE and that edge width could support, then apply another bevel, micro bevel, on top at a wider angle for longevity and durability. This gave decent results if the blade width at the shoulder wasn’t too wide. It added usefulness back to a worn wide knife and prolonged the need to regrind. IMO, to really regrind a knife it has to be an expensive, fine knife, worth the investment and requires a talented experienced individual to do it correctly and not destroy the knife or ruin the steel. You may end up spending as much on a regrind as the original knife cost, or more!
Marc
(MarcH's Rack-Its)He talks about excess heat at the micro scale which is both unobservable and unmeasureable but certainly exists.
I’ve read this opinion on the web a few times, including some impressive claims of very high heat at the local level. I have also seen it refuted vigorously. Parts of the argument on both sides made some sense. To it, I’d add that it’s possible that the work-hardening that is claimed to happen at the very edge would need to be considered as well if someone is claiming that the localized heat is changing the heat treating and temper i.e. is the alleged annealing countered by the alleged work-hardening?
To make sense of it, I guess the first thing we should ask is if our knives are behaving as though they were annealed. To most easily test it, we should take a hardened, sharpened blade and anneal it to see how it performs. Ideally, we’d have two identical blades from the same batch and we’d sharpen both, anneal one and then test them for edge retention.
-Clay
It would be interesting to run some edge retention tests after using the WEPS upside down while the knife is immersed in a bucket of water – LOL.
That’s a creative idea right there. I never would have thought of that.
He talks about excess heat at the micro scale which is both unobservable and unmeasureable but certainly exists.
I’ve read this opinion on the web a few times, including some impressive claims of very high heat at the local level. I have also seen it refuted vigorously. Parts of the argument on both sides made some sense. To it, I’d add that it’s possible that the work-hardening that is claimed to happen at the very edge would need to be considered as well if someone is claiming that the localized heat is changing the heat treating and temper i.e. is the alleged annealing countered by the alleged work-hardening? To make sense of it, I guess the first thing we should ask is if our knives are behaving as though they were annealed. To most easily test it, we should take a hardened, sharpened blade and anneal it to see how it performs. Ideally, we’d have two identical blades from the same batch and we’d sharpen both, anneal one and then test them for edge retention.
I’m not a physicist or engineer, but I find it pretty hard to believe that a manual sharpening process on the Wicked Edge really generates enough thermal energy to ruin the heat treatment of the edge. The heat capacity of the steel at the edge is relatively small (meaning that it only takes a bit of energy to generate a relatively large change in temperature) but that also means that it only takes a small amount of cooling to dissipate that energy and keep the steel near room temperature.
In looking through hypefreeblades I came across this great photo (with more in the link) and just had to share.
http://www.hypefreeblades.com/forum/viewtopic.php?f=4&t=849&start=10
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Don’t get me wrong…all this theoretical physics of knife sharpening is interesting and makes for fun conversation, but why would you ever even worry about this stuff? Sorry if I’m being an idiot. It’s way beyond the scope of the Wicked Edge Forum helping Wicked Edge users to sharpen knives with their WE Systems. Especially if your knives are taking and holding a sharp edge using the Wicked Edge System. Why would ever think about this stuff? If I had a problem with a knife I sharpened, first thing I’d consider was my technique or how I handled the knife. Then after that and a hole long list of other things, I can’t imagine ever thinking I overheated the edge on a sub-microscopic level to cause edge failure??? Sorry… there’s too many other cool things that actually impact my sharpening experience to consider.
I do love SEM photos, though!
Marc
(MarcH's Rack-Its)Well, I am an engineer and have been chasing these kinds of things for 30 years. On a specific WEPS question, I just got a new Kramer Essential AEB-L with double cryo, I sharpened it out of the box on WEPS, real nice edge, used it twice in the kitchen (nothing crazy), put it back on the WEPS to do some bevel thinning and found a small chip. Pissed me off. I use a 250x USB scope. I left the chip instead of doing all the steel removal but it reinvigorated my desire to try and figure it out. Its the same reason I get pleasure in growing better tomatoes in my garden.
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