Small knife jig adapter for very small knives

[grepper]

Herman,

That is really a very good question!  You are pain Herman! Making me think too hard. I love it! 

Thinking out loud:

To answer your question, at what bevel angles could you start to notice the difference cutting something like paper?  I'm not sure, but I doubt you would notice much difference between 10-20 degrees.  What do you think?

Then there is the whole question concerning the difference between very first edge contact vs plunging into some material when side resistance would increase as the plunge depth increased.

Does a smaller bevel angle mean that at the microscopic level, exactly where the bevel angles meet, a smaller bevel means thinner?  I'm going to have to think on that one.  What if right where the bevel meets either at 10 or 20 degrees, the very edge was only one atom wide?  One would get "duller" more quickly with a fatter bevel, but the very leading edge would be the same.

Hmmmm.....!   I presume you ask because a razor could have a smaller angle bevel than a kitchen knife, and therefore it would be very difficult to ever get a kitchen knife as sharp as a razor?  So, when trying to judge sharpness, the comparison is not fair?

Here's some light reading: http://www.ucd.ie/mecheng/staff_pages/pdfs/Gilchrist_2007a.pdf

Look at the bevel angles on a standard razor blade. A 16 degree bevel.  Not that different than a 20 degree kitchen knife.

[Herman Trivilino]

Yes, but the question is, do these different edge angles make a difference when we put them through the sharpness tests?

[grepper]

Herman!!!!

You reduced my long winded diatribe, complete with scientific documentation, to the exact same question that you asked in the first place.   Doh!   ROFL.

Ok.  The answer is no.  I don't notice a difference... Except for once..

I sharpen all knives to about 20 degrees.  I've tried 10 and 15 degrees, but I did not notice that much difference for the effort.  Now, I'm no sage o' sharpening or anything, but I've found that 20 degrees works well.  I can get that angle very sharp, easily passing the home sharpness tests.  Very useable and durable.  You might be able to get 15 degrees sharper, but for practical purposes, I don't bother with it.

However, I did sharpen one knife to 12-15 degrees and was able to cut a single hanging hair.  It was very sharp indeed, but dulled rather quickly.

I think the comparison to razor blade sharp if a good one for a knife that you are going to actually use.  Anywhere around that sharp, is, well, sharp enough.

Well, I would not do _all_ knives to 20 degrees, but kitchen, pocket and general use knives seem to do well there, and I don't have to think about it.

So I think it boils down to either sharpening for very impressive everyday use, or sharpening to see just how freek'n sharp it's possible to make a knife.  (Which is very cool).  But if the latter, then the Tromek is not the end all.  You need to study sword and straight razor sharpening, very fine wet stones, sandpaper, and hours of loving blade care.

[Herman Trivilino]

Herman!!!!

You reduced my long winded diatribe, complete with scientific documentation, to the exact same question that you asked in the first place.   Doh!   ROFL.

No.  I didn't!  I was responding to Rob while apparently you were doing the same!

[Herman Trivilino]

To answer your question, at what bevel angles could you start to notice the difference cutting something like paper?  I'm not sure, but I doubt you would notice much difference between 10-20 degrees.  What do you think?

I've noticed a difference between an edge angle of 30^o and 40^o.  I think.  It's hard to say because there are so many other factors that affect the paper test.  The quality of the steel, the polish on the bevel, etc.  All due to the skill of the sharpener!

Does a smaller bevel angle mean that at the microscopic level, exactly where the bevel angles meet, a smaller bevel means thinner?  I'm going to have to think on that one.  What if right where the bevel meets either at 10 or 20 degrees, the very edge was only one atom wide?  One would get "duller" more quickly with a fatter bevel, but the very leading edge would be the same.

Very very very far from it.  Look, for example, at the photograph you posted.  There's a legend identifying a length of 200 μm.  Now look at the width of the edge of the blade in that photograph.  I estimate it at no less than 10 μm, and it's probably larger than that.   

According to a Google search I just did iron atoms have a diameter of about 0.074 nm, or 0.000 074 μm.

So, let's do a little calculating here.  The width of the edge on that blade in your photograph is probably larger than 10 μm, but even if it were that small that would give us (10 μm)/(0.000 074 μm), or about 135 000 atoms!

We need to look at the larger structures, which are the ferrite crystals.  Not sure how big they are as I'm sure it depends on how the steel was created and subsequently heat treated.  My guess is that they contain thousands of atoms, and that the edge is thousands of crystals across. 

If this stuff interests you take a look at what a very famous physicist and delightful character, Richard Feynman had to say way back in 1959.  http://en.wikipedia.org/wiki/There's_Plenty_of_Room_at_the_Bottom

[Herman Trivilino]

Well, I would not do _all_ knives to 20 degrees, but kitchen, pocket and general use knives seem to do well there, and I don't have to think about it.

I agree, Mark.  A 20^o bevel angle, equivalent to a 40^o edge angle, is about right for most of my knives, too.  It's a good compromise between sharpness and durability.

The thing is, I bought this kitchen knife because a reviewer claimed it was thin and had an edge angle closer to 30^o making it better for slicing veggies.  It passes the paper test of sharpness better than any knife I've ever sharpened.  I guess that when it gets dull and I have to sharpen it I'll find out how good I am.  The thing is, the knife is so thin I can't measure the edge angle with the angle master and a magnifying glass!

[grepper]

Herman,

Do you like the knife?  What knife?

Interesting, this what is sharp stuff.

I guess the real sultan of sharp is currently plasma polished diamond blades.  Reportedly, edge curvature of 2 nm!  Wow.  That makes a 1 micron razor blade edge look like a baseball bat.  1 micron is 1000 nm, so they are making blades almost 1000 times sharper than a razor blade.  Rob-  Could I call that scary sharp?

Hmmm....  I wonder how that would do on our home sharpness tests?  I think I might go for the hang on a plastic pen rather than my thumbnail as I'm not sure that it would even notice a thumbnail was there.  They don't even seem to mind a rather blunt bevel, "45° and 20° trimming tools for both room and cryo temperatures."  And, "It can be sterilized in an autoclave up to 200°C".  Pretty fancy stuff.

http://www.emsdiasum.com/microscopy/products/diamond/intro.aspx

And hey kids!  We can buy them:
http://www.emsdiasum.com/microscopy/products/tweezers/diamond_scapel.aspx

Would someone here please pick up on a handful of these and then let us know what you think.... Is it sharp?

[Herman Trivilino]

Do you like the knife?  What knife?

Victorinox 40520 Fibrox 8-Inch Chef's Knife 

http://www.amazon.com/gp/product/B008M5U1C2/ref=oh_details_o03_s00_i00?ie=UTF8&psc=1


I like the knife very much and have posted about it before, I think.  Saw it on the PBS show Cook's Country.  They have a feature called the Test Kitchen where they review products.  This one was about what they call hybrid knives, knives that borrow features from both western and eastern cultures.  It's like a western kitchen knife but the curve is more sweeping, and like eastern knives it's thinner and has a sharper bevel angle.