Man cleans and sharpens old rusty knife to better than new in very satisfying video


#1

Originally published at: http://boingboing.net/2017/06/19/man-cleans-and-sharpens-old-ru.html


#2

Unimpressed cat is unimpressed.


#3

This reminds me that I want a vegetable knife.


#4

Would love to know how long it took to grind those nicks out.

Would be quite informative on the ROI of finding a decent piece of steel worth rehabilitating.


#5

… I now need to learn how to properly sharpen a knife.


#6

He uses stones of decreasing ‘grit’ but you can do the same much cheaper with wet/dry sandpaper. A blade like that will take you about 4 hours. Start with medium 80 to 100 grit, use lubricant like WD40 and sand in a single direction. Then offset the blade by 45 degrees and sand with fine 120 until the scratches from the last sanding are no longer visible. Rotate another 45 degrees and sand with a very fine 160, then 200, 280, 360, 600, 800, 1000 rotating 45 degrees with each new grit until you can no longer see the last marks. For the final polish, your best bet is 1000 grit rouge followed by a polishing compound on a buffing wheel. Another option is burnishing with a hard piece of polished steel but that will a a good deal of time. This method will remove all but the deepest spots and blemishes from any blade.

edit to add: be sure you wrap your paper around something hard like a metal bar and don’t rock it or pass it over the ridge between the bevel and the flat or you can round it out making it look less nifty.


#7

Until 3:13 when it can’t believe what it’s seeing


#8

If you use sandpaper, it is advisable to use a piece of very flat granite as a backing.


#9

I’ve had no problems using brass bars. Why do you suggest fine granite?


#10

I noticed that too. Pretty sure that’s related to their fascination with rolls of toilet paper.


#11

Do we really need to start this argument again?


#12

I put the sandpaper on clean granite, sprinkle water on it, then move the knife across the paper. That keeps the flat parts of the blade absolutely flat. The water also keeps the paper clean and sticks to the granite. The flatness is an advantage over having to dress your sharpening stones.


#13

In the US I find carbon steel kitchen knives that will take and hold a sharp edge for pretty low prices at yard sales, thrift shops and flea markets. The surface of the metal can develop a gray patina over time, but that’s usually fine as long as it isn’t actual rust.

Nothing wrong with taking it down to bare shiny metal and keeping it that way though.


#14

It is as old as time. It started when This One Dude at the back of the cave, the one with the bald spots on his arms and the huge pile of flint chippings for a bed, went for a stroll up to the Other Cave and dissed someone for napping with the Wrong kind Of Thighbone, and has been going on ever since.


#15

I get that but why granite? Will a nice thick bar or brass or steel bend under the pressure of sanding? It’s never done that to me. Myself, I prefer WD40 to water. Water will cause rust and WD40 will displace the water, provide lubrication, and prevent the rust you get from exposing fresh steel.
I also put the blade in a vice and move the bar covered in paper instead of the blade.


#16

I have a lovely steel table (2 inches thick and 4x6 feet, but it is not absolutely flat. But I have several 1 to 2 inch thick granite pieces, which I use only for this purpose. I use water for a couple of reasons. It does not harm the wet/dry sandpaper. I can use the same piece of sandpaper many times. Also, I often put a finish on the metal soon after sharpening/polishing/shaping on the stone. Usually, that means that it has to be absolutely oil free. I always dry everything off immediately afterwards, so rust is not an issue.
Some things get oiled after sharpening or polishing. I either use ballistol, which is consistent for machinery and blades from 1900 to WW2, Boeshield for modern objects, and camellia oil for very old Japanese swords and knives.


#17

Basically it’s much easier to find a machinist-flat piece of stone or glass than a truly flat bar of brass. Brass doesn’t have a flat surface after being cast or cut, it has to be machined flat, and it’s so soft it easily loses its flatness.


#18

OK, you got me beat. My 2" thick forge table’s only 3’x2’ and I thought that was a monster! It’s certainly the heaviest table I can move by myself.

It’s nice to have a table with hardy holes you can put stake anvils in.


#19

I was about to say this, granite is extremely each to get a flat piece of granite. Not only is flat granite used for household applications that are extremely flat so it’s easy to find, it’s also the material used for the base of devices used for dimensional measurement standards because it’s ability to hold it flatness under heavy use.

That said, the difference between a nice bar of brass and granite for hobby use is probably not extreme.


#20

ok, he buys knife, cleans knife, sharpens knife… THEN?

makes food into artwork.

it’s pretty effing cool!

ya’ll can argue how to sharpen knives all ya want… and this esoteric point or that.

I’m gonna go back to ?

it’s pretty effing cool!