Foolproof tool sharpening

There are two problems that can happen when your angle is off.

Over-angle where the bias in on the edge can result in a nearly imperceptible foil like fold on the very edge of the blade. You can rectify this problem with a leather strop. It will grab the foil like roll and take it off as well as smoothing any remaining material. Over time, over-angle sharpening will change the edge bevel to the point where the angle is nearly axe like in its angle. This results in a blade that is almost impossible to sharpen to a fine edge. In that case a full re-bevel may be needed to restore the functionality of the tool.

Under-angle, where the bias in on the blades body, at first gives you unsightly marks on your blade face and over time will change the edge bevel to the point where the angle is too shallow. This results in a blade which can be made quite sharp but will not hold the edge for very long.

In the end, your blades will last longer if sharpened at a consistent and correct angle.
Outdoor and sport blades should be honed between 25 - 30 Degrees
Kitchen, carving, boning, and chef’s knives should be honed between 18 - 25 Degrees
Fillet, x-acto style, razor, and paring knives should be honed between 12 - 18 Degrees
Every edge is different so sanity check your angles and don’t try to change yours to fit the above guidelines.

Get a protractor and cut some wood at the correct angle for sharpening your blade. Use sticky wax or similar to attach the blade to the wood and use it to keep your blades at the correct angle when sharpening.


You sharpen those blades with a small triangle file. It’s a pain and it takes forever but rarely needs to be done.


Except that mower blades should always be dismounted for sharpening, so’s they can be properly balanced and not ruin your blade spindles (or your feet).

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Good point! I try to balance my blades every time I sharpen them. But since I’ve never found a balancing rig that actually works on the blades of my I-5, I always end up making some kind of sloppy rube goldberg contraption on the spur of the moment that’s barely better than just counting strokes with the sharpener :frowning: . (Which is all my father ever did, and it worked for him well enough, but he was just using a push mower.)

I cook and like most people who cook, my knives are my favorite all important tools. I even take these on vacation with me, whether I anticipate needing them or not. For years I collected mostly German-made knives, but about twenty years ago began to switch to Japanese-made. These are a thinner-bladed knife generally, a bit more brittle (so don’t drop them!), feel better balanced in my hand when I’m slogging through a lot of prep work and they don’t seem to lose their edge as quickly. My hand and wrist doesn’t tire out as easily. I keep the edges straight with a few quick strops across a sharpening steel, but when they need a new edge, I hand them to my husband, who goes about sharpening them ‘old school’. He’s a woodworker with a large collection of antique chisels and wood planes, a hobby where the edge and angle on the blade are of utmost importance. He uses a small sheet of glass and two or three sheets of various grades of fine wet/dry sandpaper taped down to the glass. For lube he uses water. This low-tech method produces a very fine edge; the proper angle is just something you figure out with practice. (For the planes and chisels, he uses a jig.) There are videos online (like youtube) showing how to sharpen knives this way. I have to be kinda careful when he hands my knives back to me freshly sharpened, or I’ll add to my collection of hand scars.

Correction: He uses mineral oil or baby oil with high carbon metals.


BoingBoing does say advertisement on all their advertisements (and more prominently than some other internet sites), I would say this is a tool recommendation rather than an Ad.

Under-angle would be what I tend to do to the tips of my knives. Or used to I’m getting better at avoiding/fixing that. Tips in keeping a good angle on highly curved tips, or on long kitchen knives would be welcome.

But in my experience it isn’t, practically speaking, necessary or required to be absolutely precise and consistent to get a good edge and maintain the knife. Its easier than people let on, especially when their stumping for mechanical devices like this. My grandfather who taught me to sharpen, for example, was completely unaware of the who, whats and wheres of angles on blades. Worked entirely freehand with fairly coarse Arkansas stones. And we still have his knives. They’re still sharp, they aren’t ground down to nubs, they’re still simple to sharpen, and have few if any flaws from being maintained that way. And a good lot of them originally came from my great grandfather, and were purchased right around 100 years ago. Now I do check angles occasionally, even making various jigs like you describe. Mostly because this stuff does interest me, and I like to learn to correct my mistakes and fix damage. But you can do just fine with a few stones and taking it entirely casually, and its very easy once you learn a few basic things. Which is how I do it most times. These fixed angle, mechanical and gimmick sharpeners might be marginally easier or faster. But they can do a lot more damage over a shorter amount of time and leave you without the tools or knowledge to fix it. That’s all I’m really getting at with hand sharpening being easier, and less finicky than people let on.

Can anyone comment on how well this sharpener works versus this type of electric sharpener (Chef’s Choice Edge Select)?

I recently got one of those, and it works pretty well, but I haven’t been able to get the knives quite as sharp as I’d like for some tasks.

One thing that sharpener taught me is that all the knives we’d been sharpening by hand were off angle. We had to reshape them in the Edge Select for quite awhile before it was able to sharpen them. I’m conflicted about what that says about hand sharpening, since hand sharpening did yield a sharp edge. But hand sharpening and mechanical sharpening seem to be incompatible.

I cut furniture foam with a 12" Tramontina machete. The coarse grind is about 4.5 mm wide, and I’ve left some file marks on there which makes a nice pattern in places. On top of that is the finer grind done with the mill file and medium stones which is about 2 mm wide. This is further polished with the ceramic rod all the way to the edge, but it retains a bit of lumpiness from the file work. I resharpen it a couple times an hour to put on the 1 mm wide cutting edge.

And you prefer that to a diamond type sharpener? Guessing you’ve used both?

The only guy I know who professionally cuts foam (he insulates pipes, ducts and boilers) purposely puts a ragged edge on his knives. He sharpens big cheap knives with bricks and lumps of concrete. I call it “Poor man’s microserrated” and it looks like hell but does seem to do the job. He says he doesn’t want a high quality knife because it will get covered with glue and/or stolen on the job.

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The Chef’s Choice I used in the past required that you let the magnet hold the blade at the right angle. It then worked fine with enough patience (took longer than I expected).

I know these belt sander types work but I don’t think gaining the skill to do it by hand using just a piece of sandpaper laid on a piece of glass is that daunting. Most of the blades we sharpen are wide enough to put a finger under the blade to hold a reasonably steady angle.

I will admit my preference these days is a Lansky style tool, with slots for a few fixed angles. I started with “natural” stones but switched up to diamond grits. They seem to stay flatter. The natural stones wear faster and then need to be dressed (again using sandpaper on glass) too often. Most of the skill with this tool is knowing what grits to start with and feeling for the rolled-over edge (time to switch knife sides or go to finer grit).

I’ve dug a few diamond sharpeners out of the drawer and used them lately. They seem useful for taking off the high spots I think I’d use diamonds more if I were using stainless steel or hollow ground blades.

Yes that works on a closed cell insulating foam, and those cut well with bread knives or the classic Ginsu. But that sort of knife will just tear an open celled furniture foam. An electric carving knife or $300 reciprocating cutter is the usual solution.

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Poor Deluded Dupes – why must y’all cling to such crude methods when one can simply harness the powers of the universe:
Method of Maintaining Razor Blades and the Shape of Straight Razors.


The best choice for amateurs is the Spyderco knife/scissor sharpening kit. It’s probably the best choice for professionals too. Belt sharpening is guaranteed to roll over the edge, the only cure for that is to then stone the opposing angle, and it takes a deft, practiced hand for that. I have used the Lansky system, diamond stones, grinding wheels, and strops. I have stuck with the Spyderco for the last ten years. It is easy, maintains the proper angle, and doesn’t over-sharpen (hone) knife edges so that they break down after just a few uses.


40 and 50 degree only? Because western chef knives need 20 degrees and Japanese chef knives need 15.

I dunno if it is worth it. You sharpen once a year or less and the guy at Chef’s Warehouse will do it for 3 bucks.

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Hey, are they all customarily sharpened on the left side or right side? My brother gave me a couple Japanese Global knives that I haven’t really tried to sharpen.

i have had this "system for about 2 years. I ruined one “cheapie” blade while learning to use it - it is, bar none, the best sharpener I’ve ever used. blah blah keep talking, blah blah. but? this? is a fantastic tool sharpener.

I’d like to know the principle of sharpening used in making Fiskars hatchets. Those things stay dangerously sharp for a long time even after chopping lots and lots of wood. But then i never use them to cut tree roots or similar abusive use.

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