Testing for SHARP

Darrel Ralph

Darrel Ralph

Joined
Dec 14, 1998
Messages
4,870
I see all of these posts for how to make an edge sharp. There is many ways and different
opinions.


NOW How does everyone TEST for sharp.



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Web Site At www.darrelralph.com
Happy Holidays!
 
Must shave a patch of hair off my arms like a gillette without the barbasol shaving cream
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[This message has been edited by exsanguinate (edited 12-15-2000).]
 
I'd like to find a good standard to test all my knives. Right now I get it to hair popping and then go from there cutting leather and chopping and whittling on a 2x4 to make sure I have the angle right for that blade. Shaving hair is a good test but I'm tired of the bald spots on my arms. You should see my arms after a show, looks like I have a skin disease.
Unfortunately it seems that most people looking to buy a knife test by shaving hair so that needs to be kept in mind, either that or educate them right at your table on how to test one.
Jon
 
Hold piece of cimputer paper in air, drop it and cut it lengthwise on the way down. My tramontina kitchen knives pass this test!
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For smaller blades, but the shorter way. Then go to regular paper that it a little thinner. The bald arms look is getting old and I am not shaving me legs!!!! Also, slicing fruit/vegies in mid air is always fun.
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I like to use the thumbnail test. Holding your fingernail or thumbnail at about 25-30 degrees from vertical, if the edge 'grabs' or 'bites' when pulled lightly across the nail (using no pressure), it's sharp. If it slides off, the edge needs more work. Also works on tupperware, or other hard plastics.
 
I usually use corrugated cardboard as a sample cutting medium for testing an edge. Its rough on an edge and you can very quickly judge an edges shapness. At least it is what I am used too. Maybe that is the most important thing. With one of my own knives that I am sharpening for the first time, I tend to sharpen, test cut, hone, test cut, touch up on a different stone, test cut, etc. There is a period of exploration involved with a new knife and they are all a little different, but I alwayds smile when they whiz through that cardboard.
 
Do you think slicing newspaper is a good test?
My question is what about harder testing materials. Shaving is easy!
But what happends when you test cut tough materials?
Then what happends?
What should be the test after the shaving and paper and cardboard?



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Web Site At www.darrelralph.com
Happy Holidays!
 
Darrel: Here are a few good ones:
1) cut cleanly through a standard size cigarette paper that is super glued to a piece of nylon sewing thread and suspended from the ceiling. I use CLUB papers-they are extremely fine and have a high fiber content. Glue the thread to a corner of the paper. It is acceptable to leave the paper folded-it helps keep the breeze from moving it out of the way as you cut it.
2) roll a newspaper sheet into a 3" diameter tube. scotch tape just the ends.
stand the tube on end-cut through it diagonally and leave the base standing on the table. this works best with blades 5" and longer.
3) cut a piece of 1" NEW hemp rope, hanging from the ceiling. End must NOT be knotted, and you must cut within 6" of the end. I have done this with blades as short as 3 1/2"
This test is good for measuring edge holding as well. People say rope cutting is irrelevant. The people who say this make knives that can't cut rope. Enough said.
4) Since arm shaving is pretty easy, try popping off individual hairs using just the knife's tip.
5) Shave the ink off a magazine (glossy)photo.
6) Shave a curl off a business card.
7) Drop your hand onto a knife clamped in a vise and see how many hours of surgery are required to put you back together. NO-DON'T DO THIS!!!!!!! I did, by accident. It was a hell of a way to demonstrate that my knives are deadly sharp. Good news, you only have to do this test once-then, you can just show them the scar!! HAHAHAHAHAHA

Stay Sharp,

RJ Martin
 
RJ
Cutting free hanging rope is a trick. I know what you mean
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Sounds like good tests to me.

This is the good stuff.

MORE MORE MORE




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Web Site At www.darrelralph.com
Happy Holidays!
 
I found this one by accident while sharpening in the living room shortly after one of my kids birthdays. There was a helium balloon on the ceiling with a free hanging ribbon attached. I took an ideal swipe at the ribbon. The ballon did not move, but the lower part of the ribbon just fell away. I found out later that this is Very hard to do.

Paracelsus
 
I skiv leather, basically shaving off layers. The last thing I do with any knife before giving it to it's intended owner is to use it to make its own sheath.

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Oz

"Nonsense. I have not yet begun to defile myself."
http://www.freespeech.org/oz/
 
I like standard news print paper.

You can not only feel how sharp the blade is, but you can feel (and/or hear) small knicks in the blade edge that you can't see.

I just draw the blade through a piece of standard newspaper from base to tip.
 
the ole finger nail trick , hair shaving , paper cutting ( fast and slow ) if she passes those tests with flying colors i let her go!
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i keep grinding and grinding and it is still too short!!
 
The knife must shave hair off of both arms. This way there is no wire edge, on one side of course. And when the knife owner tells me how many deer or wild pigs they cleaned and it is still sharp and they are happy do you see me smile.

Happy Holidays
Jeff
 
I like to slash Vampire Gerbil and see if hes says "OOOOO" or "ouch"..if he says "OOOOOO" its sharp enough
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When I'm sharpening a blade I use the dead skin on the tip of my thumb to feel the edge. It tells me if it is sharp, and if I have dull spots or pieces of the wire edge left. After that I cut all sorts of stuff to see if the edge holds. Carving wood and cutting leather are two of my favorite test because I can test various properties. An example is using dried wood to test the strength of an edge when it is used to break out chips. With leather I like to cut thin curls and strips. This tells me if the edge is consistent along its length and how the material is moving past the edge.

I try not to cut myself but manage to do so every now and then. One thing I've learned from accidentlly cutting myself is that dull knives really don't cut much and sharp knives cut deep : )
 
Basically, if you can see the edge its not sharp enough. But, I like the thumbnail test. Lightly drag the edge across your thumbnail, and if it grabs, its sharp. I prefer the micro sawtooth edge instead of the polished edge. I use the fine and ultrafine DMT stones and then the strop the edge on the back of an old leather belt. Plenty sharp after that!

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Danbo, soul brother of Rambo
 
I agree with Andrew on this one. Leather has always been a good "medium" for me. Chopping dry wood THEN shaving with it is always a good. I don't think my teenage kids would believe the cigarette paper thing....they would probably accuse me of going thru mid life crisis!
 
<font face="Verdana, Arial" size="2">Originally posted by Jeff Pelz:
The knife must shave hair off of both arms. This way there is no wire edge, on one side of course. And when the knife owner tells me how many deer or wild pigs they cleaned and it is still sharp and they are happy do you see me smile.

Happy Holidays
Jeff</font>
Click to expand...

Great, Now i'm gonna have bald spots on both arms. I guess my arms will match anyway. :-)
Jon

 
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