How long does a knife last...

S

stitchawl

Joined
Jul 26, 2008
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This isn't a question. It's a consideration.

Let's start with a knife that 'John Q. Public' uses. Perhaps it cost between $50-$150. Even those of us who are knifeknuts 'usually' don't spend much more. (Of course there are the random 3 or 4 who put out $250 - $350+ for a Microtec Auto or a Sebenza, but they really aren't part of the general public.)

So we have someone who either carries an EDC, works with a knife on the job, or has nice knives in the kitchen. He's (or she's) zealous about maintaining an edge on the knife and so sharpens it on stones once a week. He's (or she's) fairly knowledgeable, with a bit of skill, and so doesn't just hog off a lot of metal each time, but does remove a bit. How long is that knife going to last? (This IS a question.) I'm going to estimate between 15-20 years depending upon the steel. Perhaps they only put the knife to a stone once every two weeks. So the knife will last 30-40 years. How about the guy who only sharpens on a stone once a month. That knife is going to last almost 80 years!

... and you're worried that your knife is going to get 'used up?' And you are concerned that you might have to spend another hundred bucks before you turn 90?

Knives are tools. Tools meant to be used. (Yes, I know... I'm not talking about closet queens here.) Even a Sebenza is meant to be used, and if you have to replace it after 80 years, it still only cost you half a penny a day to own. It's not gold bullion, nor is it the Prom Queen. It's a tool that was made for use. Don't worry about how much metal you are losing if you sharpen it once a month. And unless you are cutting up sheetrock or cardboard (and you shouldn't be; there are sheetrock knives and box cutters made just for those,) you shouldn't 'need' to sharpen your EDC more often, not if you are treating the blade properly between sharpenings.

Sharpen once, steel and/or strop a dozen or two dozen times, then sharpen again... IF IT NEEDS IT. A knife, any knife, should last a good long time if you don't abuse it.
 
I'm sort of watching for this, with a couple of Victorinox paring knives I've been using. I've 'volunteered' them for lab rat duty, in the sense that I've used them to tinker with different hones and to tune up my own freehand skills in the process. I've lately settled into touching them up a couple or three times per week, using a handful of very, very light passes on EF diamond hones (DMT's 1200/9µ); I like how these blades respond to those hones, leaving a wicked-sharp and essentially burr-free edge, needing no stropping. I can't visibly see any retreat of the edge yet, even with these 'soft' blades with thin grinds. Many of my other knives get stropped fairly often with relatively fine, but aggressive, compound like white rouge; I do them that way, because I've liked the finish produced for how I use those blades. BUT, I've also noticed more visible metal removal on those knives, over time; mainly in how the blades have gradually become thinner near the edge (and I'm not complaining about that, BTW).

I really do believe that many blades get quickly used up because the methods used to 'touch them up' are just too much overkill for what's actually needed at the edge. I occasionally read posts on the forum describing how a moderately 'dull' blade gets run through the whole sequence of grits each and every time it's 'sharpened' (Coarse stone... raise a burr... remove it...; Medium stone... raise a burr... remove it...; Fine stone... raise a burr... remove it...; then onward to stropping with a sequence of grits...). I can't help but think it's likely not necessary for what's needed most of the time. Unless a blade gets completely neglected, it usually won't need much more than what the last one or two grits can handle on their own, with a minimum of passes on each. If the good edge geometry gets set in place the first time, it shouldn't be necessary to regrind everything from the start, each time. Maintenance becomes almost effortless if the foundation of the edge is set properly, and if smart choices are made about how stones or strops are utilized in maintaining them.


David
 
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My mothers 55 year old kitchen paring knife is down to its last 1/4", and it was sharpened on those double wheel put thru sharpeners
My 8" 45 year old Sheffield carbon steel cooks knife gets sharpened by a couple of passes on a DMT E Fine once a week before use and it is full size
 
Kitchen knives see a lot of use. My Leatherman sees more. I sharpen it every week. I try to avoid taking it to the stone as long as I can by stropping. This escapes stone work for 2-3 weeks. So, it sees the stone once a month. Still, after 10 years it's lost 3/16" of blade length and some in the width. IF it makes another 10 years, I'll purchase a new one. I see more blade wear with kitchen grade steels. So, this has a play in the equation. My hiking & hunting knives have up grade steel and may get sharpened once a year. So, they last much longer. A good topic, Stitch. DM
 
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Funny you bring this up. I have seen some Spyderco pm2's around that look like they are at the 80-90 year mark.

Are guys using bench grinders on these or what?
 
My EDC use is fairly light. My older knives have a lot of wear on the outside from carry, but not much wear on the edge or the mechanism.
 
I'll tell you the inspiration for starting this thread...

I was rummaging around in one of my knife drawers and came across the 'Buck Stockman' I was given when I was 18 years old. It was my first 'good' knife. Up until then I had been using Boyscout knives of one sort or another. Because it was a 'good' knife, I figured that I needed to sharpen it every day... I knew how to sharpen a knife freehand since I was eight years old, so this was no trouble... for me, at least. Not so good for the knife.

By the time I was 25, this Buck Stockman didn't look so hot. The Sheepsfoot blade looked more like a bird's foot, the Spey blade looked like an awl, and the main blade was missing the first 3/4 of an inch in length and half of its width. I never noticed it going. It was time to re-think the process.

Who the hell ever told me that a knife needed to be sharpened every day? Probably no one. I just figured that if it was 'supposed' to be sharp, that meant daily sharpening. I don't think I ever bothered to check to see if it needed it or not. Probably not.

I'm a 'utilitarian.' I don't have any 'Closet Queens,' nor do I keep my EDC in a slip case to protect it when it's in my pocket. The only time my pocket knives go inside a sheath is if I'm wearing dress clothes and I don't want it to imprint on my pants. That happens about once every 8-10 years... I DON'T CARE IF MY KNIFE WEARS OUT THOUGH USE. I don't care if the blade gets scratched up during sharpening. I don't care if a drop of paint or Superglue gets on the handle. It's a tool, not a keepsake. But I'll be damned if I'll ever wear out another blade through useless, unneeded sharpening!

My EdgePro gets dragged out about once every 8-12 months, and SOME of my knifes get a workout. Otherwise, it sits in the closet. My Sharpmaker lives on a shelf in the kitchen, with the fine rods set up. (I don't bother with the ex-fine for kitchen duty.) SOME of kitchen knives will get touched up every few weeks on those fine rods... 5-10 strokes at most. My EDC, a 'Benchmade 710,' probably gets the most frequent actual sharpening, usually with the DMT Aligner and diamond stones. I probably do that at least 2-3 times a year. But the kitchen knives get 'steeled' for EVERY use, the 710 gets stropped EVERY use, and the chances of me ever wearing out another knife in my lifetime is about zip... BUT.....

... That's just because I've learned about knives and how often then 'need' to be sharpened, NOT because I'm worried about having to replace a tool. Tools are tools. They aren't jewelery. They are designed to be used, and tools used often and hard they are going to wear out. That is NOT the end of the world. It's just the end of a tool's life. We can replace it easily.


Stitchawl
 
Good post and good explanation there Stitch. It boils down to just good common sense and paying attention to your "tools" and taking good care of them. I don't re-work my wrenches after each use. I just clean them up and put them away for the next time I need them. (not really a good example, but the idea is the same) There are some that must have their knives with a mirror finish, and sharp enough to split hairs. Nothing wrong with that, but it is not very practical. My knives, like yours are users, and are normally sharp enough to get the job done that I require of them. Most of the maintenance is done with the steel to re-align the edges (kitchen knives) and they only need re-grinding about once every 2 or 3 months. My edc happens to be a #6 opie and gets sharpened whenever it will no longer cut easily. I do run it on the slotted wheel of my paper wheels to "tune" it up most of the time. I only grind it about every 3 months. It shows little sign of wear. From what I paid for it, it will outlast me with just normal care.

Omar
 
I tried this out about a year ago. I gave an old knife about a years worth of sharpening in a couple of nights. I was careful and mindful of not over sharpening. I resharpened about 35 times. Average blade width loss was about 0.0005". So in a year of sharpening, it lost 0.015" of width. I didn't measure length.
 
me2 said:
I tried this out about a year ago. I gave an old knife about a years worth of sharpening in a couple of nights. I was careful and mindful of not over sharpening. I resharpened about 35 times. Average blade width loss was about 0.0005". So in a year of sharpening, it lost 0.015" of width. I didn't measure length.
Click to expand...
neat :)
Hmm, 0.381 millimeters , were you burr sharpening?
52/35 = every ~1.5 weeks ... so you're not steeling or microbeveling just "full" sharpening each time? :)
What do you use your knife for, what are you cutting and how often?
 
That particular knife is a kitchen knife I got at the local flea market for $7. I really use it very little except for utility work and sharpening experiments. It was burr sharpened, but I was careful to only get the tiniest burr I could detect. I also used a mixture of free hand and guided sharpening. I do not use steeling or stropping as a general rule. Once I have a knife tuned to the way I sharpen, I can fully resharpen it in as little as 2 minutes, depending on severity of use. It takes as little as 20 passes per side to get that tiniest burr, then cut it off, and alternate 20 more and done. I do microbevel, but its part of applying the final edge, not maintenance between sharpening.
 
I was watching this show with a japanese iron chef (forget his name) and he showed a few knives with different years of use on it. And his 3 year knife was sharpened to a stub.

I have 3 year old knives that look new, and are scary sharp.

My secret, i ONLY use an 8000 grit stone. Minimal metal removal, but still maintains a very keen edge.

I want a NEW yanagi, but mine has many many years left if I keep my polish routine.
 
Sir Pizza has locations all over the world supposedly. I've only been to a few in the Miami area. The one on Key Biscayne has been there forever and they cut every pizza (into squares) with a large kitchen knife. It's probably got a 12" blade or so. Once when I was there, the guy using the blade told me it was the original that's cut every pizza since the beginning. He held his finger out and said "it used to be this long", indicating 3 or 4 inches longer. This is just an anecdote, but they are claiming to have lost around 3" of blade length in 30 years of sharpening a blade that gets used a bunch. I'm not sure if I believe it or not. <shrug>

Oh and their pizza is REALLY GOOD. Try it if you're ever in the area. :)

Brian.
 
It's good to remember that 98% of 'professional' kitchens send their knives out to be sharpened by machine once a week... or more. A professional chef in a large restaurant doesn't have time to sit down and spend 30 minutes sharpening a knife, especially if he has a roll of 5 different ones!
These are sharpened by people who sit all day at either wheels or belts, and whose only concern is that the knives get sharp. They have absolutely NO interest in the life span of a knife, or even if the knife is $20 supply-house plastic handle job or a $250 hand-made Japanese queen. They can spend roughly 2-3 minutes on each knife (if that long) and are interested in 'production' not beauty.

Yes, there is the rare (professional) chef who does do his own sharpening, and it's certainly something that is taught in every Culinary School around the world, but a pro generally doesn't have the time. A butcher doesn't have the time to do more than steel an edge. A meat packer just picks up a knife out of the box marked "Sharp" after throwing his dull knife into the box marked 'to be sharpened.' Commercial knife sharpening is BIG business!
 
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