Trouble sharpening Henckels knives
I have a full set of Henckels (mostly five-star). They are 20-25 years old with light daily use.
I simply cannot get and keep an edge on them all of a sudden, even using the techniques I have always used. I am an advanced hobbyist woodworker and can put an edge on a plane blade that allows me to make a wood shaving I can see through. I have a full set of oil and water stones. I have even paid (ughhh) to have the knives sharpened -- and within a day or two: dead.
My regular routine is to set a primary edge of about 20 degrees and a compound edge of 25-30 degrees. The knives are finished off with a 6000 grit Japanese water stone.
I use a bamboo cutting board. The knives have never seen the inside of a dishwasher.
So....I hear from Williams and Sonoma that knives this old can lose their ability to hold an edge. I'm not sure I buy that, but my experience has me spooked.
Anyone else experience this?
All right, on the assumption that this issue is affecting the whole set, I agree it's probably a loss of hardness at the edge. [Bear in mind when these knives were made, they were first put into basic profile while soft, then the whole blade blank hardened, and then "drawn" or tempered back down some to the desired final hardness, and lightly finish ground and the edge bevels put on]. When you get the edge too hot in resharpening on a moving wheel or belt, it can anneal the area, basically returning the metal in that area to its original softness (which defeats the purpose of using toolsteels in knives!). Even thick blades are so thin near the edge, it takes very little time on a power tool to spoil things.
How attached are you to these knives? Do they have great sentimental value to you? If it is just a matter of $$, I'm sorry, you should consider junking them.
However [and I'm only suggesting this because you are an advanced woodworker], you can salvage them.
Plan A: You might consider carefully drilling out the cutler's rivets, popping/burning out the scales, and sending the "blanks" to a good heat-treater for a re-do. Others here will be able to tell you the exact alloy, and the treater will have a set "recipe" for the harden/draw. A uniform final hardness is just fine--you shouldn't need to worry about getting fancy with selective quenching, temper lines, etc. Then you can re-handle your set any way you want, maybe with a fancy chunk of fall you've been saving for something special. If you send off to the heat treater, here are a couple tips: (1) make sure you grind the edges DEAD FLAT DULL (edge dead on your tool) so that they are about as un-knifelike as a butterknife's back, otherwise you're gonna get stress risers and cracks when they're treated; (2) make sure the holes in the tangs are as many or the size(s) you want (or larger) BEFORE heat treating, or else you're screwed.
Plan B: There is a guy (another knifemaker) whose link was listed here on CH not that long ago who specializes in rehabbing old/abused knives. The OP of that thread had a lot good to say about his service and prices, and his website convinced me that he knows what he's doing. Sorry I don't remember his name. You can probably find it with the CH search function.
Hmmm. With the information you've given us so far, this is looking like a real mystery. There's nothing about an older knife that would make it just lose its edge keeping ability on its own.
First, big clarification - your problem is not that the knife won't get sharp, but that it won't stay sharp for even a day or two, right? If your knife will no longer get sharp in the first place, we're looking at a very different problem than the issues I'm about to brainstorm (in which case I suspect the other guys are right that you might need to thin behind the edge - you might not be hitting the edge while sharpening, and a large cutting bevel makes it harder to do so reliably. There are other possibilities though if this is the problem)
So assuming that your knife will take an edge but not hold it-
My first thought was that you had sharpened it past the point at which the steel is still tempered. But you said there is no step at the bolster, so it's quite unlikely that you got anywhere near that far.
Second thought - your edge has slowly grown more acute than the Henckels is willing to take. But if you're sure you're sharpening the secondary bevel at 25-30 deg, there's no way that's the case. We would be talking probably below 15 deg per side if this were the case. But, being a woodworker used to chisels, maybe you reckon edges differenly than we do. Is your edge 25-30 degrees per side (50-60 total) or included (12.5-15 deg per side)? Have you measured your angle?
Third thought - did you have this problem before you had someone else sharpen the knives? I'm wondering if the other fella ruined the temper with a fast wheel or belt. No other exposure to (very) high heat?
Fourth - could be a simple problem of a wire edge/intact burr. I wouldn't really expect this to be much of an issue with a Henckels sharpened to 25 deg/side at the edge, but who knows. Are you deburring after your coarser stones?
Fifth thought - is someone else in your house routinely using your knife directly on a marble counter-top and just not telling you?
Sixth and final thought - gremlins.
"I'm wondering if the other fella ruined the temper with a fast wheel or belt. "
That may be the probable explanation, especially considered that Skilpll said "I simply cannot get and keep an edge on them all of a sudden" I simply cannot imagine how an entire set of knives all went bad at the same time. They are not all going to suddenly have thick blades behind the edge and they are not all going to suddenly change the steel crystal. Especially Skilpll is an advanced woodworker.
Skilpil. You may want to clarify this. Is your problem: (1) you can an get the edge sharp, but cannot keep it more than a few days or (2) you can never get the edge sharp? These two situations are very different. On one hand, you said "I simply cannot get and keep an edge on them" which points to situation 2. On the other hand, you wrote "I have even paid (ughhh) to have the knives sharpened -- and within a day or two: dead" which suggests situation 1.
The older knives might have been case hardened, such that the hardening reached the center of the metal in the thinner parts, but not quite in the thicker parts of the knife. If that's the case, you'll never get them to stay sharp if you've removed enough metal to move the edge close enough to the spine to miss the hardening.
From what I know, ancient swords dug up thousands years ago can be sharpened, so I really do not buy the idea that an 2-30 steel cannot be sharpened. I am really amazed that people come up with stuffs like this. Seriously, I cannot even dream up stuffs like this. In all honesty, people from Williams and Sonoma aren't exactly knife experts.
I think scubadoo's theory can be correct. Through some of what you said, does not seem to match up. For example, you wrote "I have even paid (ughhh) to have the knives sharpened -- and within a day or two: dead." So you are saying that they can be sharpened, but the edge does not last more than a few days. I would think if the blade is thick behind the primary bevel, then it just does not feel as sharp in day 1 and it should not have the "sudden deterioration" experience you had.
Anyway, to thin out the blade can be time consuming. A more practical method is to put a back-bevel and primary bevel as scubadoo has suggested. For example, put a 15o back bevel and then put the 20o primary bevel. Basically, the following:
I think scubadoo is right about thinning.
Rather than have all the flats reground (difficult and expensive) or having a tall secondary bevel ground in (a little unsightly), you might want to take/send the blades to a pro sharpener who does good rolled (convex) edges (e.g., Bob Tate, Bob Kramer's understudy). I think this would thin out the blades enough that you can then have a few additional years of your own fixed-angle resharpening. It'd also give you an idea of how good a rolled edge can be.
I contacted Bob and will probably go that route. By the way, I mentioned the rolled (convex) edge and he did not seem to know what I was talking about. Maybe that is not his technique? Anyway, he seems to have great references, so I'll go that route for now and use a ceramic steel. Still disappointed I could not get a good edge on these knives, since I was always able to do so before. Maybe I'll find out something after Bob works on them.
Not sure what you mean. "Thinned?" And by "behind the primary" do you mean the secondary bevel or the flat of the blade. I can't imagine the latter has an effect.
I have tried primary bevel only (which is what most home sharpeners and shop sharpening is), but also done primary/secondary bevel.
I also have Henkles knives about 25+ years old - they were called Four Star when I bought them IIRC. They've been my only knives over that period and have gotten a good bit of use. I also am having trouble keping them sharp now. My technique isn't anywhere as technical as yours...I didn't do anything but the steel until about 8 years ago, and now take them to the little local sewing machine shop every year (if i'm lucky) and just hone on the Henkles steel in between. This served me well until lately - now it seems they just won't hold an edge. I really don't want to replace them for "sentimental" and economic reasons, but I need good knives!! What to do?