How to sharpen a knife

mickri

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I have never made a knife and right now don't intend to. I have never been able to sharpen a knife. My dad was fairly good at. He tried to teach me. I never figured it out. About 10 years ago my kids gave me a set of sharpen stones for Christmas. I tried and tried again with no success. Recently I have learned how to grind really sharp tool bits for my lathe using a delta 1x42 belt sander with a light touch up with one of the stones from my kids. I had never thought about using a belt sander to sharpen a knife until now. Watched a few videos online and today had at it with two of my always dull kitchen knives and an equally dull folding knife that I use all the time for everything imaginable. My results while still not very good were better than I had ever achieved in the past.

What I have to work with is 80 and 320 grit belts and a stone with a rough side and a smooth side. Don't know the grits on the stone.

Suggestions please.
 

lordbeezer

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More than likely you're gonna get 50 different opinions..goggle is your friend..then you'll have a few more ..good luck..you'll have to pick which way works best for you.
 

mickri

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I realize that I will get lots of different opinions. I am just hoping to find some combination that will work for me. One video I watched opined that you really had to have a microscope to inspect the edge and you were wasting your time without one. Others showed whipping the blade back and forth held at different angles by eye using progressively finer grit belts and leather strops. I will just keep trying different things until I hopefully find something that works for me. I may never achieve much success. I am knife sharpening challenged.
 

mikey

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You are not the only one, Chuck. I use my belt sander but I lay it down with the belt horizontal and stand behind it so the belt is running away from me. I then attempt to hold the knife at a 25 degree angle and run the blade across the belt, accelerating and rounding my movement near the tip. This has resulted in some pretty sharp knives despite not using a microscope. A few passes on my water stones and I'm good to go. I probably suck at it but the stuff I cut in the kitchen and shop haven't complained yet.
 

lordbeezer

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I use mostly Arkansas stones in different grades.has worked for me for a lot of years.also have Norton stones.diamond laps.depends on the blade..pick up some good stones.learn your angles and you'll be in business ..
 

cathead

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Once a knife is shaped to the basic correct geometry, I find using a 400 grit diamond 2x6 inch flat hone works really well. They are
available inexpensively on E-Bay so I have several, one in the kitchen and several in the shop. It just takes 4 to 6 swipes
at the right angle for a good tomato slicing edge. Also they are handy in the shop for fine tuning carbide cutters. Another plus
is that they don't wear down or wear out for that matter.

It makes a big difference in what kind of metal one is sharpening. Some stainless steel is really hard to get a good edge
on as well as softer steel blades. I like to use a carbon steel blade in the kitchen as it holds a good edge. My Chicago Cuttlery
stainless kitchen knives are only OK and my carbon steel blades are far superior.
 
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Tozguy

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You are not alone in that question. After struggling for years I came upon a book: THE COMPLETE GUIDE TO SHARPENING by Leonard Lee (of Lee Valley fame). I was amazed at how much there is to know about the subject. As mentioned above there are several versions of free advice floating around on this subject but this book is worth every penny it costs. It might seem like overkill as an answer to your question but the information in this book applies to such a broad range of situations that it should be part of any hobbyist' library.
 

mikey

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I have it and will re-read it. Thanks.
 

ThinWoodsman

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Aah, but the trick is to create the proper geometry first. For blade sharpening neophytes, that is the challenge.
I made a few of these recently: Kanna trimming tool. In my prototype I laid out the edge geometry using a belt sander, but wasn't happy with the results (oddly, that tool rest for the sander never built itself). I put the finals in a vise and shaped the edge by hand using files, which took forever. It was easy enough to use kitchen knife sharpeners for the straight edges, but the curved one is still giving me trouble - the emery-cloth-on-a-dowel approach proved too unreliable. Might have to make the equivalent of a lap or a hone to get the final edge on one.

In regards to the original topic, for already-shaped knives I use two kitchen (bench) stones: a 6000 grit whetstone and a DMT diamond that is 8000 mesh or something. Put the stone on a small cookie sheet, dribble some water on it, and do the ol' figure 8 motion, slow and light. Move to the finer grit once a cutting edge has been produced.

I recently picked up a strop block (basically a kit where a leather strop is glued to a wood block and loaded with compound) for touch-up after knife use, but have not assembled it yet.
 

Bob Korves

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If you overheat the blade, you will take the temper out, and though you may get it sharp, even razor sharp, the edge will be ruined and willl not last long. Belt sanders (and bench grinders) are the best way to ruin a good knife out there. It can be done, but it must be done without the cutting edge getting hot. The blade may be fine, but the cutting edge may be soft. Sharpening knives by hand has worked well for millennia, and only requires a good stone and technique. Keep it sharp and then freshening the edge only takes a minute or two.

I was a professional chef for my first career, and we did not love and fondle and revere knives, we used the hell out of them constantly to get the work done, and a dull knife is slow, tedious, and dangerous. Much of the advice for sharpening knives on places like YouTube and Google searches are either worthless, slow, dangerous, and/or do not achieve a good, working edge. I still have my knives from that time, and they are all kept sharp and well cared for, and are used daily.
 

Tozguy

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What I have to work with is 80 and 320 grit belts and a stone with a rough side and a smooth side. Don't know the grits on the stone.
I have several different sharpening systems but for kitchen knives I use ordinary wet/dry sandpaper on a flat surface overhanging the workbench. There is a delightful choice of grit sizes and the broad surface makes it easier for longer knife blades.
Once the right angle has been established it is really quick to refresh the edge just by laying out a sheet of sandpaper on the bench. It is imperative to have good angle control since the angles will vary depending on what the knife is used for.
It is also easier to keep knives sharp if done regularly so you need something simple and quick to set up and use.
Oh and the food tastes so much better when its prepared with a sharp knife.
Just a reminder that much sharpening frustration is caused by poor quality steel. A kitchen only needs a few good knives so buy the best and treat them well . Did I already say your food will taste better?
 
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pontiac428

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I like good knives, and I select my carry each day from a Gerstner chest atop my dresser stocked full of S35VN, N690Co, CPM154, D2, Elmax, and other fine steels. As a hobby machinist type, I like fixtures, so I use a Wicked Edge sharpener. If you've never seen one, look it up. I finish and tune up my blades regularly with strops. I still have all of my fingers, but I've used up all of my Band-Aids.
 

mikey

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Okay, I'm getting the message that I shouldn't use my belt sander to quickly re-establish the edge geometry. Instead, use my stones to do that. I used to do that but I apparently suck at it because I could not get a consistent edge. Maybe I need to practice more.
 

pontiac428

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When I was in 3rd grade, I got a little folding knife (a Klein) and a hand-me-down Smith's Arkansas stone. I still have that stone on my workbench, and I think it is my last remaining possession from my childhood. Anyway, I worked and worked that edge on that stone until, years later, the blade was a thin sliver of what it started as. I can hand hone a sharp, but rather round-profiled edge freehand, then get a shaving edge with a strop, but it's nothing like the keen edges I've seen from the hands of old timers. That is why I use a mechanical fixture now. It should be in my DNA, but apparently that was replaced by a weird perfectionism that only likes perfect edges.
 

Tozguy

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My 2'' folding pocket knife goes everywhere I go. I paid a lot for the little puppy cause was to be kept razor sharp. Good steel is so easy to sharpen and it stays sharp because of how carefully it gets honed and stropped.
Angle control is all important so use fixtures if necessary. At the right angle it only takes a few strokes to get it done. At the wrong angle it only takes one stroke to ruin the edge.
Old timers got lots of practise because they used hand tools and knew how much more work it is to use dull tools. And then to be disappointed in the ****ty results. In 1962 I saw a carpenter at the plant where I worked cut a 2x4 on his knee with 3 strokes of his cut off saw, clean and straight.. His hand was strong like a clamp and I think his arm was made by Caterpillar.
 

Bi11Hudson

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Like everything else in today's world of engineering marvels, true sharpening has fallen by the wayside. In my father's younger days (ca,1930), everyone (except the ultra rich) used a straight razor. And kept it sharp. Cutting whiskers with a dull razor is painful! He taught me a couple of tricks to sharpen (then new to him) double edge razor blades. Back in the days of "glass" table settings. In our modern society, such razors are no longer readily available. Not even at a Barber Shop.

I have a Lansky rig modified for doing wood chisels for a friend in the wood flooring business. I use the original fixture with diamond hones for doing knives. But the grade of steel makes a large difference in how long an edge will keep. Like a knife, a good chisel will hold an edge much longer than a cheap one from the hardware store. But to do it with a power machine, never. Not only the only time it can be sharpened is in the shop, but how long have machines been around compared to how long knives have been extant.

I have a couple of "Bucks" (one a 110, one a penknife) and a "KaBar" penknife for when I need a good edge. Then a "Leatherman" and several "Kleins" when I am working. In electrical work, you need a knife that is sharp enough to cut insulation, but not so sharp it will gouge the copper.

The modern "tactical" knives serve no real purpose that I can see. Except being hard to sharpen with the wavy edges. The Buck 110 was from my sailor days (ca,1969), a good all around working knife. But scary to people around me when I pull it out these days. It is under the legal limit, barely. But bulky, intimidating to those that don't do work with their hands. So I don't often carry it these days.

I don't use a straight razor, hell, I don't use a razor at all any more. My hands shake these days. But the point still applies, we as a society have to deal with cheap steel and loss of an archaic skill. I don't know a solid solution, it is something that really needs to be acquired in childhood and "honed" as we age. Just like a good knife.

This is becoming a "rant" for me, a sore point for a long time. So I best lay it to rest before it delves into the political aspects.
Bill Hudson​
 

pontiac428

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The straight razor is a distinct exception. I only use a straight blade, and sharpen it on a Norton 4000 grit water stone by hand (to form the profile) and strop (to shave hair). The blade on a straight razor has a T-shaped spine that guides the blade and determines the angle of the cutting edge. They are easy to sharpen. Doing the same on a disposable double edge blade would be tough!
 

mickri

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I have enjoyed all the replies. It gets down to technique which I have never been able to master when using a sharpening stone. An it just might be that the knives I have currently and have had over the years are just pieces of junk that would be a challenge for a master to sharpen. I will look up a wicked edge sharpener.
 

ThinWoodsman

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There's a guy on youtube that pokes around at different sharpening techniques burrfection. I've only watched one or two of the videos but the guy sharpens knives offhand on whatever stone is around - brick, paving stone, whatever. Worth a watch.
 

Janderso

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Don't buy a hardware stone.
Buy a quality stone, then hone your technique and take your time.
Once you have it sharp, a steel touch up is all that's needed.
 

mickri

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Looked up Wicked Edge sharpeners. Expensive. Never going to happen on my budget.
 

pontiac428

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Yeah, I finagled a pro deal at the time, I think I paid 40% of retail on the Wicked Edge. I had all my stuff in storage at the time, else I would have made one. It would have been a fun project to do in brass. The basic idea is very simple. The marble base was an embellishment that I am glad I bought. If you are interested, I can take some dimensioned photos...
 

mickri

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In watching the videos on sharpening a common theme was that when you get the two edges to meet a burr will form. No burr means that there are multiple facets at the edge of the knife if I understood this correctly. I got this burr to form when I was using the 80 grit belt and somewhat when I went to the 320 grit belt. Sometimes all along the edge and sometimes only along portions of the edge. And then on a subsequent pass the burr would disappear. Then it might come back and then just as mysteriously disappear again. I have no idea what I am doing wrong because I can't tell that I changed anything in how I presented the edge to the belt. This is where I am at right now.
 

ThinWoodsman

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It is going to be difficult to get an edge (the burr) on the entire blade using a belt sander unless you use a fixture or jig of some kind. I would suggest moving from the sander to a stone once you get the burr formed, that will slow you down so you don't lose the progress you've already made. When moving from a coarser grit to a finer one, I always reduce the pressure on the stroke. Same angle, same motion, less pressure, and slower movement.
 

Bob Korves

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When you use your knives 8-10 hours a day, 6 days a week, for 10 years, sharpening at least a couple of them every day, you watch the old timers, ask questions, and learn how quickly. I have been away from that work for almost 40 years now, and I can still sharpen a knife without hardly even looking at it or the stone. No additional aids beyond knife, two hands, stone, and tap water. Checking the edge against a fingernail tells a lot...
 

MarkM

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I ve found myself wanting my own shop and realized it would be years before I can be tooled up and such and wanted something to help the business out on a steadier basis as it s mostly repairs and stuff around here.
The idea was that it would be easier to get to a point in the sharpening aspect as it s much cheaper to get there.
I bought a Tormek T8 wet grinder. A swedish machine. It honestly is one of the best machines I have been around. It s quality and design is great.
After I am done honing on the leather wheel with the Aluminum Oxide Compound I can take a pc. Of chicken breast a lay it in my hand amd split it without holding it. First thing my customers do is let staff know how sharp they are. It really keeps an edge for some time.
I have a few different of there grinding wheels and a whole whack of jigs. Super precise doing angles and the jigs are very well engineered. For knives there are three jigs. Not just for length but also flex.
It has become facinating learning about sharpening. Quite challenging and way more going on with geometry than I ever thought. Scissors for example has so many things going on you have to know what your doing or there junk.
The biggest seller to customers is the slow wet grind. Grinding on a bench grinder or belt as Bob says takes the temper out because of the thinning of the edge.
For stones make yourself a wooden jig to establish your angles. Count your strokes with consistent pressure.
I must have at least three grand into by now but man it does a good job and love having the ability to put four facet grinds on my drill bits.
Has a continuous duty motor and comes with a ten year warranty.
 

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Tozguy

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Mickri,
once there is a burr along the full length of the blade stay on the same side but with finer grit. Make sure the blade does not heat up at all, quench often with water. Continue on the same side with lighter pressure until the burr falls off. Touch up the other side on a fine stone.
If the burr comes back you are using too much pressure, too coarse a grit or the wrong angle.
Making a heavy burr too easily could be a sign of poor knife steel.
 
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