Chips in Edge After Sharpening?
- This topic has 21 replies, 7 voices, and was last updated 12/08/2017 at 11:00 pm by
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Are you sure the chips weren’t there before you started sharpening, Eric? A loupe or a microscope can be a good friennd.
As you noteed the stones are not broken in yet and that is a likely reason. In order to minimize that effect, try not to put too much pressure on the stones and used edge-leading strokes as much as possible.
Molecule Polishing: my blog about sharpening with the Wicked Edge
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I would expect a Santoku style knife, even of a less hard steel, to be able to support 18º per side. But you may need to step up to 20º per side when all said and done.
New, not broken in stones are quite rough on an edge, ceramics included. Did you observe the knife was magnetic because it stuck to a magnet or because the metal filings stuck to the blade? All of my knives including the “Stainless Steel” knives are kept on magnetic wood knife blocks on the wall. The magnets hold them quite securely.
Sometimes an edge is so damaged that it needs to be debrided with a file taken at it 90º to the mounted knife across the edge to remove and flattened all the damaged steel. I use a medium bastard metal file for this so as not to abuse my WE Diamond stones. I find it best to file in the same direction as the knife is clamped, heel to tip to heel. Be careful not to slip off and cut or injure yourself.
Then when profiling the knife I use the coarsest WE Diamond stone capable of removing steel easily with out a lot of effort. If you can get by with 200 grit, have at it.
What kind of results have you gotten with other, maybe better, knives with your WE? What stones and progression are you employing? Prior to and after the ceramics? The more details you provide the more all of us can learn from your experience and share our similar experiences.
Marc
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I have also seen knives with the issue you are describing. I have a hunting knife that was given to me as a groomsmen gift that I have tried to sharpen at least 5 times over the years. The metal filings appear to have a magnetic property where they collect on the blade and I have never been able to put a respectable edge on it. I have tried free hand sharpening on Arkansas stones, a Lansky, and more recently the Wicked Edge. I have the same problem on that knife with all of those tools. I can get it sharp-ish, but not even close to how sharp I have been able to get other knives. I think the poor quality steel is to blame. It is made of some kind of mystery stainless steel and I think the heat treatment is not correct.
For your neighbor’s santoku I think your best plan of attack is to sharpen it up to about 600 grit at 20 degrees like Marc suggested, strop it up, and move on. I suspect that it is never going to be great. However, your neighbor will probably comment on how it is now amazingly sharp and is even better than when it was new.
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Mark, Marc and Organic list a series of points that I would agree with 100%. I’ve seen steels that do this and invariably, they’re cheap and probably have been damaged in the heat-treat process. Heck, I’ve got a Kershaw Shuffle that I believe was never hardened by the maker.
Fractures along the edge are usually indications that there are stresses in the steel. Bringing the edge to a sharp apex seems to weaken the structure that holds the metal crystals together.
I will add one point that I think may also be contributing to your problem and that is using 100 and 200 grit stones – especially new, un-broken-in stones – at the apex. I had some really bad experiences with it early on and have tried to never get close to the apex with coarse grits. Think of an abrasive being pushed along the surface of the steel. As it progresses, it pushes some of the steel ahead of it. When it gets to the edge, the strength of the steel drops off dramatically and there’s a chance a chunk of the steel at the edge will break away.
The following photo is an example of a 200-grit stone breaking away a piece of an edge. In this case, I think the stone had not been fully broken-in and that a cluster of diamonds may have been the culprit. But the principle is the same. There simply isn’t as much structural strength in the steel near the apex.
From your description, I don’t think this is your specific problem. I’m sharing this with you to help you understand what happens at the apex. This particular knife (your santoku) may have a perfect storm of issues. Cheap steel, badly heat treated and sharpened at too low of an angle? And (this is a reach) maybe the coarser grits are weakening the edge in spots?
Before coming to the conclusion that your ceramic stones are faulty, consider that they work fine on other blades. I’d accept that the knife has limitations. Select a higher bevel angle – maybe 22 dps? – and sharpen up to 1000 or 1500 grits.
Before signing off for the night, I’d like to say that I am a big proponent of MarcH’s suggested method of filing the edge flat until the deepest chips are eliminated at the apex. I use my 800-grit diamond stone for this (it normally takes only a few strokes). Some call it de-stressing the edge, but I think Marc’s use of “debriding” is more appropriate. If de-stressing is in fact correct, maybe that’s one of your answers.
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Now I’m going to contradict myself for the statement that “invariably, they’re cheap” or badly heat treated.
I had an episode of chipping on my Spyderco Delica 4 in ZDP-189. I quickly deduced that the chips were being produced by my relatively new 800-grit diamond stone. Here’s a photo:
The culprit was a cluster of diamond particles which were unluckily oriented in the long direction on the stone face. Every time it touched the very hard (Rc-64) edge, it broke off another chunk of steel. The stone had been used for 20 or 30 knives and should have been well-broken-in, but the orientation of the cluster resisted any normal sharpening forces which might have knocked it off. Perhaps you can see it in this photo:
For me, the answer was to chuck up a section of 1/4″ plate glass in my vise and in a half-dozen strokes or so, the cluster was gone.
@Mark76 – I am pretty sure it wasn’t there at the beginning…. I think…. :-/…. Next on my list is one of those USB microscopes.
@MarkH – I said magnetic because the filings stick to things…. the edge included… looks like magnetic filings from high school physics/chemistry. I should actually just step it up to 20 degrees… this user isn’t the most delicate anyways. More details about my progression bellow. This is my second knife, but the first one was a higher quality santoku (mine) and came out great. Not mirrored, but I didn’t strop it at all. I’ll have to try that file trick. Sometimes people give me some knives that they… well… haven’t sharpened since they got them 30 years ago….
@tcmeyer – Awesome info. Thanks.
When you guys “destress” or whatever. You mean run the stone flat (perpendicular to the blade)… basically what I would do if I wanted to destroy the edge?… just to get the holes out of the edge? I’m assuming I’d be looking for a shiny smooth line from tip to heel if I looked straight down onto the blade.
My progression…
100 or 200 to profile and form a burr on both sides, then alternating passes about 10.
200 (unless I started at 200) alternating passes – 20ish)
400, 600, 800, 1000, 1500, Super Fine 1200, Super Fine 1600, Ultra Fine 1.4u, Ultra Fine 0.6u . … all about 20 per side alternating.
I wasn’t sure about the 1500 before the 1200 super fine….
Thats where I have been stopping for now as I’m not aiming for mirror.
After that I have 6u Diamond Film, and then strops with 4 and 2 Micron Paste. I was thinking about doing the 4 and then 2 micron strops after the ultrafine… should I do the diamond film first?
I presume my order is correct, any issues with my process? Any other stones/films/pastes I should add now? I was going to try to break it all in before I added more…
Thoughts?
Yes the distress is perpendicular to the blade. Sometimes I don’t remove every divot. It would be wasting too much usable steel . I sharpen the knife as best as I can leaving only the deepest defects. The knife still is very sharp and works very well. Each time I sharpen this knife I’ll continue to work out the bad defects and also the newer defects. There’s a balance you have to be OK with. If every time you sharpen a knife you distress it or debride it till it’s a flat shiny surface looking straight down on it, the knife wouldn’t last very long till it was too wide at the shoulder to slice nicely.
Your progression listed above is fine if your seeking a highly mirror polished edge. When sharpening an everyday use kitchen knife I strive for a good sharp working edge. Not a “for show” polished edge. I usually follow the progression through 1500 grit diamonds then strop 4µ, then 2µ. When I was first starting, a new WEPS user, I too attempted to use every stone and medium I had. I tried to line them up and find the perfect progression. That’s all part of the learning process and it helped me to learn what it’s all about.
The grit progression doesn’t follow a linear line of decreasing particle size, (increased grit number) when switching mediums. I often step back up a grit or two when making this change. The grit chart helps with this understanding, but nothing like personal experience, will. I still continue to try different things and experiment with different progressions, from time to time, to see if I can find that “better” edge.
Marc
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Thanks for the help all.
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I think your progression is good. I don’t own the ceramics, but most people who do have them seem to substitute the 1500 for the 1200 / 1600 set and then proceed directly on to the lapping films skipping the ceramic stones all together. I would suggest trying different combinations and seeing what works best for your desired results. The ceramic abrasives work in a completely different way than the diamond stones or the strops and it is unclear just exactly what their equivalent grit ratings should be. There are some old threads on the topic where Clay has shed some light on the subject. Check out Mark76’s blog on the Wicked Edge if you want more information on the ceramic stones.
If you’re not going for a mirrored edge, then moving to 4 / 2 micron strop after your current progression should yield a very nice edge. I highly recommend stropping. If you test an edge by slicing paper before stropping and then again after stropping you will see why.
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Eric: Back on the perpendicular filing of a damaged edge…
For me, the primary purpose is to speed things up and clarify my purpose. Consider that all of the steel above the root of the deepest chip has to be removed. You can do this in a few easy strokes done perpendicularly or you can toil away at it in your normal way, checking now and then on your progress. It really does make a big difference in time spent.
You don’t usually have to remove the apex for the entire length of the edge – heel to tip, just in those areas where the damage is. If the damage is so great that this results in a deformation of the edge, as in creating a concave belly where there shouldn’t be one, you’ll want to straighten the edge profile as well. For instance, a concave belly in a chef’s knife will make it difficult to cut flat on the cutting board; the knife simply won’t cut cleanly through veggies where this “rise” is held above the board. This provides another instance where it’s time advantageous to file the edge back to a straight (or more correct) profile. Here, the time advantage could be twenty to one.
I often get kitchen knives which were hand-sharpened on stones, belts or steels for years, leaving deep bellies just ahead of the heel. Before starting the stoning process, I re-establish the arc ahead of the heel by filing or sanding the edge back into alignment. These jobs are more repair jobs than re-sharpening jobs. It takes very little time if you get rid of that steel that rises above the maker’s intended line. Don’t hone it off, cut it off; meaning file or sanding belt. Honing takes too much time for such huge amounts of steel removal.
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