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CompositeEngr
01-05-2003, 01:22 AM
Another non-machine tool question for the folks on the board:
Knife sharpening!
I have never been good at it. I have a medium Arkansas stone, and I tried it on my Leatherman (which I have abused). Made some small improvement, but not much.
I then tried it on my Swiss Army knife, and now I can shave with that one.
So, the questions would be:
1. Is it the steel, the abuse, or the operator?
2. What is the best technique? I used a medium hard pressure on the stone (lubed with water) like taking a thin shaving off the top of the stone, then three or four swipes at the same angle, but reversed direction. The 1st step cleaned the edge nicely, then after the second step the good knife would shave the hair off the back of my hand easily.

Thrud
01-05-2003, 02:06 AM
I sharpen most knives on a 15micron SiC belt. If you do not screw the angles up, it leave a razor sharp edge, whice is then honed on a leather strop with Chromium Oxide.

The leatherman is stainless, so it will be more difficult to get a good edge.

ralenr
01-05-2003, 02:41 AM
Given reasonably good steel, stainless or high carbon, any knife can be made to take a sharp edge, properly sharpened. Therein lies the real question. How does one properly sharpen a blade?

Two recommendations that have served me very well are: "The Razor Edge Book Of Sharpening" by John Juranitch and the Ceramic stones supplied by Spyderco http://www.spyderco.com

The book covers how to effectivly sharpen just about anything with a cutting edge. The stones are great. I've used oilstones, Akansas stones, the diamond impregnated steels and Japanese waterstones and these are far and away the best I've ever used.

I've been using the techniques in the book to sharpen various edges using the Spyderco stones for years. Both are highly recommended.

Allen

halfnut
01-05-2003, 04:35 AM
If that blade is in bad shape you got to get it close to sharp before putting it on the Arkansas stone. Drag out the India or Aluminum Oxide first then finish with the Arkansas stone.

Look at the edge, can you see the edge, if you can it's not sharp keep working on it with the coarser India or AO stone. Once its sharp use the Ark to get off the wire edge and put the final keeness to it.

Sounds like your rock technique is correct, pretend you are cutting off slivers of the rock with each pass, alternating sides.

3 kind of knife edges, honed, buffed which slightly rounds the edge, and then there is the butchers edge. They use a rock to sharpen, then they use a steel to keep the edge straightened up, they'll use the wire edge that most try to hone off. Scary sharp, but fragile, if the knife just doesn't almost cut by itself they grab the steel and start swiping on it.

SGW
01-05-2003, 09:55 AM
You may want to try a diamond stone. The steel in the Leatherman may be extremely hard. I have a little single-blade knife that I always thought was not much good because I could never get a decent edge on it. Then I tried a diamond stone. Wow! Once I got it sharp with the diamond stone, I finished it off on an Arkansas. But the steel was so hard, it was just taking forever to get to the "sharp" stage with the Arkansas stone alone.

h.w.evers
01-05-2003, 11:02 AM
To sharpen all lengths of blades, from 1" pen
knife to Samurai sword, use a Lansky sharpener. Does all types of steel, including the stainless used in diver's knives. It sharpens only the edge, does not scratch the rest of the blade.
The secret to sharpening a knife blade is to stone both sides of the edge at the same angle at that location. The angle will change slightly from the hilt to the tip, but as long as the angle is the same on both sides, you'll get a nice sharp edge.
The Lansky comes with 3 stones, from course to fine. Additional grits are available, as well as diamond stones and Arkansas stones.

Howard W. Evers

h.w.evers
01-05-2003, 11:05 AM
WARNING: If you use a Lansky to sharpen the kitchen knives, you MUST WARN your wife. Most women do not have experience with a truly sharp knife and can cut themselves without realizing it. NO JOKE!!!!

Howard W. Evers

kgarver
01-06-2003, 05:14 PM
To know when the edge is sharp set it on your thumb nail and slowly pull it towards you. When its sharp it will automatically "dig in" and you'll be able to feel it. When there are sections that are not sharp (there will be!) it will just ride up or slide over your nail. Resharpen those sections!

Hellbender
01-06-2003, 08:40 PM
I'll second the Lansky, I never got a knife REALLY sharp until I got one. You can even do a double or triple angle on the cutting edge.

------------------
NRA Lifetime Member

Thrud
01-06-2003, 08:51 PM
HB
This is much like grinding drill bits - it takes time and patience, but once you get good at it - it's no big deal.

You do not need the Lansky - use the force, Luke. http://bbs.homeshopmachinist.net//biggrin.gif

shaque
01-06-2003, 11:27 PM
Well I have been a sharpener for well over 20 years and have to agree with most of the stuff that has been written here, but I will add a couple of more things to the list, first after you think you have it sharp, finish it off with a hard felt wheel impregnated with a honing compound (I like the green stuff you get at Lee Valley Tools. Now if you want to tell if its sharp, look at the edge in good light. If it looks shiney, its not sharp, you should not be able to see the edge. Now to check even further take a piece of cloth or waste and drag it acrross the edge, if it does not snag, its sharp.
Jim

Thrud
01-08-2003, 01:57 AM
Jim
Having witnessed the extremes of sharpness exhibited in japanese swords, I am in awe of their ability to get such keen edges. Even my straight razor at its very best is dull in comparison.

ShavingMaker
01-08-2003, 08:29 PM
I will go Mr. Evers one better... Never, ever, sharpen a kitchen knife! The cook is used to it being dull, so don't interrupt the hacking.

docsteve66
01-08-2003, 08:35 PM
right yuo are shaver. Bought the wife a nice set of carbon steel knives. The BIG chef knife is mine. Its sharp the rest are just likewife wants them. Irest knife on tomato, it slices thin, just drops through. Wife don't admire my knife none no how!!!!

gizmo2
01-08-2003, 10:57 PM
my favorite 'how sharp is it' story is from when Britain ruled the world. British officer in Turkey, bragging about his Shefield sword. Unsheaths it, and with one fell swoop cuts cleanly through a 3" sappling, toppling the tree. Turk says, "Yes, that is impressive. But I believe my Kris to be equally sharp, if not more so." Lays the blade on a feather pillow, and it cuts the pillow in half with its own weight, without ruffling the feathers. Isn't that a grand tale? I'm sure the particulars are botched but you get the drift. I agree about kitchen knives; you can buy the war dept. a new knife and she may respect it, but to sharpen an old one is at best a fools' game, at worst a trip to the ER. Been there, done that, bled all over the t-shirt.
I like the diamond hone for truly abused edges, the Spyderco Tri-angle (black) for most everything else, and carbon steel blades. They are getting hard to find, though. They touch up quickly, so it's easy to keep a good edge. Keep them away from the better half, though. If she doesn't cut herself right off the bat, she'll throw it in the dishwasher to get that edge down to a usable dullness.

Hellbender
01-09-2003, 09:43 PM
<font face="Verdana, Arial" size="2">Originally posted by Thrud:
HB

You do not need the Lansky - use the force, Luke. http://bbs.homeshopmachinist.net//biggrin.gif

</font>

http://bbs.homeshopmachinist.net//biggrin.gif http://bbs.homeshopmachinist.net//biggrin.gif

Tibertus
01-09-2003, 09:59 PM
My favorite story is told by William Manchester in his great book "The Arms of Krupp". Old man Krupp is at an Industrial Exposition in England. He is looking at this gigantic ingot of hard steel that the English had made. The English steel guys know who he is and walk over, "well, what do you think? this is the biggest hardest ingot of steel ever made" Old man Krupp pulls out his Krupp steel pocket knife cuts off a small slice of the ingot admires it and says "yes this is good steel". (Read the book too long ago so I can't quote directly sorry about that).

Man I'd of loved to been there that day.

Peace

grannygear
01-09-2003, 10:50 PM
I too have the Lansky sharpening system, and the sharpening book by Juaritch, which I swear by.

The book makes several key points that have become my sharpening mantra:

One, you can pick any sharpening angle between about 14 and 20 degrees, doesn't really matter. What matters is that, once you pick an angle, stick with it and don't change it during the sharpening!

Two, the lubricant is there to remove the debris away from the blade. It can be water, oil, kerosene, even compressed air. Keep the blade clean.

Three, once you've picked an angle, sharpen one side of the edge until a burr forms along the entire length of the opposite side. Until you've done this, you haven't sharpened enough. Then turn the blade over.

Four, use whatever sharpening medium you're comfortable with. Diamond (very aggressive), ceramic, waterstone (basically silica clay), Arkansas stone, whatever. Some people swear by sandpaper (aluminum or cerium oxide) glued to a surface plate. Belt grinder, same thing. Just get an angle, and don't deviate from it!

The Lansky system allows you to do all that in a foolproof (idiot proof, in my case) system. The blade and stone are held in a fixture so that the angle can't change, and it's also easy to put a relief angle on the blade for greater longevity.

And Thrud, of course the Swiss Army steel is also stainless!