The fastest way to sharpen a knife into a razor

Factual Questions
1

Hi, my first post.

I want to sharpen this old knife I got from my grandpa. I still remember how this knife was really sharp when my grandpa used it. He once cut a bit of my curly kid hair off my eyes just by carefully lifting the hair with the edge of the knife.

I looked into different crafts forums how to sharpen edges. I honestly admit I did not get the most of it at all. Moreover when someone started a topic on the issue there started at some point some kind of strange philosophical debate (or sometimes a fight) apparently leading to nowhere on my behalf.

All I asked for was a simple and quick way to sharpen a piece of steel. Yeah I picked up some advices (I think) but the process in itself is still a bit vague to me.

For example considering the result, what kind of real difference there is between a felt wheel and a strop? I get that the felt wheel runs in a bench grinder and the strop is essentially a handheld device. But what is the difference in result?

Then, can I “felt wheel” or “strop” after a grinding stone or is it somehow “illegal”?

Thanks for reading. :slight_smile:

2

Probably the surest way is to determine the degree of bevel on the blade, then cut a wooden wedge at that angle, and sharpen your blade using an old-fashioned whetstone or oil stone. The wedge will maintain the proper angle as you stroke the blade across its length against the stone. It’s a bit awkward.

There is a sharpener made by Spyderco, called the Triangle Sharpmaker. I have one and it works very well. It comes with a DVD that shows you how to use it.

3

I use a Crock Stick to put the final edge on my knives. On a properly prepared knife, it will put a razor-sharp edge easier than any other method I’ve used.

4

I went to a local pottery hobbyist’s supply store and bought a ceramic tube.

This tube is about a foot long, 3/4 inch in diameter and a wall thickness of about 1/8 inch.

I attached a handle to it, and use it as I would use a sharpening steel.

I can take a blunt knife and after about thirty strokes on each side, I have a knife that is sharp enough to shave with.

It works perfectly with both carbon and stainless steels.

Total cost: about $3.00.

5

Belgian Coticule whetstones are legendary but they’re probably overkill.

6

I had to look into this recently as well. I had bought a lovely Böker damascene knife and wanted to find a way to get the best edge from it. I can’t guarantee that the following is correct, but I think it is.

There are 2 main considerations. The first is that cutting edge is uniform. Blades can get dented and pitted with use. When that happens, you first need to rebuild the cutting edge with a course sharpening tool. This will take off a certain amount of metal, but it’s necessary to restore the uniformity of the edge. Yes, you can sharpen the dents and pits, but now you have what amounts to serrated edge instead of a flat one. That’s probably not what you want for shaving.

The next consideration is the fineness of the abrasive. If you look at a sharpened edge under a microscope (which I actually did, believe it or not), even a relative fine abrasive leaves small grooves in the edge. You can’t see it with the naked eye, even on close inspection, but they’re there. I’m not certain, but I think these grooves give the blade, even though sharp, a rough feel. You won’t notice for cutting sisal rope, but you probably will for something more delicate. I think this is why people recommend sharpening with a whetstone and an abrasive with a high grit count. I’ve seen some as high as 6000 grit.

Oh, one more thing. Sharpening tends to leave burrs along the edge, so once you’re done sharpening, you want to use something to remove the burrs but not dull the edge. I think that’s where strops and such come in, but I’m not sure.

7

The fastest way? - Go to your local butcher’s shop - they will probably sharpen it for a few bucks. At home use a sharpening steel to keep the edge longer. Repeat as necessary.

8

I got plenty of reasonable answers and tips. Thank You everyone.

Special thanks for this post.

9

Hi,

This has been a journey.

It took it’s time, but now I can honestly say I Can do something really useful with my hands (and eyes).

I have two DMT diamond sharpening stones, coarse and medium. I use water with those ones.

Then I have a Danish made electric bench grinder you usually see equipped with two stone wheels, but now I got both of them replaced with hard wool felt wheels.

Those felt wheels are made of “industrial wool”, which is actually organic sheep wool from Australia or New Zealand (mostly).

The Industrial Wool is generally used for making oil absorbing cloths against spills in garages and workshops, because sheep wool has this unbelievable property of absorbing oils many times it’s weight.

These bench grinder wool felt wheels are compressed and cut to make a really hard wool polishing disc product which still exploits the oil and wax absorbing property of wool.

I have a thick bar of paraffin oil softened carnauba wax -binded polishing wax which is filled with 1 micron alumina powder. The alumina is so-called “superground”, which means it is ground down to a single crystal level. It is therefore really tough and sharp powder particle in this form.

I assure you fellow Straight Dopers, once you got you hands into the same gear I have, this world will be much more peaceful place with all of those UNBELIEVABLY sharp kitchen knifes everyone will have at their disposal.

Mind you, the Coarse DMT is really for severely chipped edges. You do not really need it unless you are fixing all kinds of chipped hardened steel, stainless steel, high speed steel or TC back into a shape.

The Medium DMT is seriously good piece of gear to have around.

The real razor appears really in just a few seconds with the hard wool felt wheels and proper rouge, powered by a decent bench grinder. Polish the edge always with the rotation.

I can cut the hair just by touching the hair halfway with the edge. No need to move the knife with the skin at all.

Even the most useless knifes are brought back to life just like that. My sushi/sashimi kitchen has never before been as “clean cut” as it is now.

I feel seriously good. Straight Dope is certainly credited here. :slight_smile:

Yours,

Sasamu

10

Sasamu

It sounds like you’ve got everything you need. If you are interested and feel like playing some time, look-up a technique called “scary sharp.” This uses various grits of fine sandpaper, a piece of window glass, and some spray glue. I’ve been using this technique for some time and always get good results. It also cuts down on the amount of stuff on your workbench.

Regards

Testy

12

reported

14

Reported.

15

If you’re question is “fastest,” it would be using a mechanical grinder, either belt or platen or paper wheel. The drawback is having to switch to finer progressions. If you ask which method will best work for idiots, then the many assisted systems like the spyderco sharpmaker, the lansky system, or the wicked edge. The fastest non-mechanical method would still be free-handing using a good progression of stones. This requires the most skill. Of the above methods, only the assisted systems do not require undue training and skill.

Felt wheels and strops get the same result using different procedures. Both need practice and correct methodology.