knife question for Stig

[Ken S]

Great quote, Tyler.

As a traditional telephone man in a mostly rural area, I climbed many poles installing and restoring service. However, I never did, nor had any desire to do, the showy trick climbing the lumberjacks do. I guess I'm the same way with the Tormek. Tyler, I recommend you work with the tried and true Tormek wheel graded coarse, when appropriate, then graded fine, followed by the Tormek Honing compound. Once you have become very fluent (keywords "very fluent") with this basic combination you may wish to experiment. Being proficient with the basic combination will give you a solid basis and good point of reference to begin your experiments. Don't get me wrong; I think expanding our knowledge base is a very good thing. I just think we need the base first.

I would describe Steve as more than "very fluent".

Ken

Ken

[Herman Trivilino]

OK, Gentlemen,
what are you all polishing the  edge with? Steve referred to a 1500 grit wheel. What else?

The leather honing wheel. It removes the burr and polishes the bevel.

[grepper]

I know I am probably asking repetative and stupid questions, but.....

T

And in the rare case you ever discover you have actually asked an insanely stupid question,
or even blurted out a profoundly ridiculous utterance,



And, really!

[grepper]

Hopefully on a less comical and more actually helpful note...  if you ever want to really polish the edge, after taking it as far as you can with the Tormek, you can always:
https://www.econabrasives.com/products.php?id=273&size=1X42

I have found that if you work your way through the grits with these things, you can get a polished edge where scratches are barely visible even under a microscope. 

[Ken S]

Well, there we have the graduate level polishing answer. I trust that when you have achieved that level that you do not degrade the edge by actually using it.

One of my favorite sharpening books is Leonard Lee's book. I like his DVD, too. I have both in my personal library and have often recommended them for your personal libraries. At a bare minimum, please check your local library or interlibrary loan.

Leonard Lee has a practicality based on many years experience. I believe him when he states that for most woodworking when an edge has been honed to 4000 (Japanese scale), that edge has reached the practical sharpness for almost all woodworking. For those of you interested in competitive wood planing or other trick shows, that is not enough. For those who are interested in building furniture or letting in hinges, 4000 is plenty.

Incidentally, Leonard Lee's book is not a Tormek specific book. However, in recent years, his company, Lee Valley, has become a Tormek dealer. The information is solid and very readable.

Ken

[grepper]

It is interesting to note that the Tormek honing compound is supposed to be comprised of equal amounts of 1,2 and 3 micron abrasives in suspension with mostly oil and ammonia.  As that application of compound is used, the larger particles break down and the smaller particles become more significant.  In theory at least, toward the end of an application's usefulness, only 1 micron abrasives would be left.

Consider the following:
http://www.gessweincanada.com/category-s/11328.htm

The finest grit super fine polishing belt I linked to, is about equal to a fresh application of the Tormek honing compound @ ~2 to3 micron.  Therefore, after exhausting the finest grit belt, the edge could be further polished with the wonderful Tormek honing compound.

So to achieve a super polished edge, why bother with the belts at all?  Why not just sharpen with the Tormek wheel as smooth as possible, about 1,000 grit, and then hone?  The answer is that right off the 1,000 grit wheel, the bevel still has pretty deep, (comparatively), scratches.  Additionally, because of the nature of the stone grader and the grinding wheel, even when the wheel is graded to 1,000 grit, the abrasive surface is not consistently even compared to micro finishing belts.

When that edge is then honed on the leather wheel with compound, the areas between the scratches become nicely polished and shiny, but the scratches remain even though to the naked eye the edge has a mirror surface.  In theory the scratches could be completely removed and the bevel polished to the limit of the compound without the belts, but one would have to have a LOT of spare time and a good supply of honing compound on hand to pull off such a feat.

So to get a very highly polished edge in a reasonable time, sharpen to 1,000 grit on the Tormek, then work through the grit levels of belts, then hone with the Tormek compound.

I photographed this process some time ago so you can actually see it rather than just accept the idea.  In this instance I stopped sharpening @1,200 grit and then honed with compound.  As you can see, even though the bevel is highly polished and extremely sharp, scratches are still plainly visible.  Sharpening to 1,000 grit on the wheel, and then through several grit levels up to 12,000 grit with belts, followed by honing with compound would, for all intents and purposes, completely remove the scratches.  It would be a nice, very shiny bevel.

I mention in the post magnification of 200x, but looking at it now, I believe it's more like 50x – 100x:

http://forum.tormek.com/index.php?topic=1689.msg7998#msg7998

[Herman Trivilino]

I agree completely, Mark. I can see the scratches left by the Tormek grindstone with my 40X microscope, and after polishing on the leather wheel the scratches remain, but the spaces in between the scratches have a mirror finish.

This got me thinking about the magnitudes. If we have a 0.5 micrometer abrasive, that will leave scratches of roughly the same size, 0.5 μm. That's equivalent to 500 nm, which is the wavelength of visible light. So essentially scratches of this size will not be visible at any magnification. You'd need an electron microscope to see them. That would be the definition of a mirror finish.

If the Tormek grindstone could be prepared to 1000 grit it would leave scratches on the order of 20 μm. This is about 40 times larger than the wavelength of visible and is clearly observed to not be a mirror finish, even with the naked eye. And that's easily confirmed with a 40X dissecting microscope or the like.

[grepper]

Sure is fun having a microscope, isn't it Herman!

It's cool to be able to actually see exactly what's happening during sharpening and honing.  I've found it invaluable for understanding abrasives, edges and sharpening.

[Herman Trivilino]

For me, a microscope ended that frustration that occurs when you just don't seem to be able to raise a burr and get a sharp edge. If could be because the grinding hasn't yet reached the edge, that the steel is so hard it doesn't make a burr, or both. But you just don't know. Without a microscope you can't tell, but with a microscope you can.

[Ken S]

I have two related questions for the microscope people on the forum (I use the term "microscope people" as a compliment.):

1) Does the amount of time spent on the honing wheel improve the smoothness of the edge? If so, what kind of time are we talking?
(Does five minutes honing produce a noticeable improvement over one minute?)

2) How does the amount of time spent refining the edge relate to the endurance of the edge? In other words, does spending an extra minute translate to the longevity of the edge? (Does that minute spent on refining the edge mean an extra minute; five extra minutes, or how many minutes of keenness?)

Ken

[Herman Trivilino]

1) Does the amount of time spent on the honing wheel improve the smoothness of the edge? If so, what kind of time are we talking?
(Does five minutes honing produce a noticeable improvement over one minute?)

Once I get a polished bevel and can see the mirror finish I stop. This takes probably a minute or two as long as the leather has been properly prepared. That is clean and impregnated with compound. I doubt that further honing would make any difference.

2) How does the amount of time spent refining the edge relate to the endurance of the edge? In other words, does spending an extra minute translate to the longevity of the edge? (Does that minute spent on refining the edge mean an extra minute; five extra minutes, or how many minutes of keenness?)

I don't know about this. I haven't noticed any difference and wouldn't know how to tell. The knife is going to get dull faster depending on what tasks or abuses its been exposed to, and I don't how to isolate these variables from the one you're asking about.

[tylers]

First to All,

Thanks very much for the help and advice. I suspect that my life span is not long enough to get on par with Steve B.
Grepper - love your sense of humor; made me chuckle for a while.
I have read Leonard Lee's book also. Don't have his DVD yet though.....
I must not have the leather honing wheel properly prepared, as I am not happy with the finished product. Maybe too much oil?
On to more practice!
T

[tylers]

Also,
does anyone (Herman?) make and sell Herman's extended jig/plate?
I'd rather buy one than take the time to make on, as I have plenty of other items to attend to.
T

[Herman Trivilino]

They are not sold anywhere that I know of, and I was told it's not appropriate to offer them for sale here on this forum.

[grepper]

I have two related questions for the microscope people on the forum (I use the term "microscope people" as a compliment.):

1) Does the amount of time spent on the honing wheel improve the smoothness of the edge? If so, what kind of time are we talking?
(Does five minutes honing produce a noticeable improvement over one minute?)

How long should you hone?  It depends.

Honing accomplishes two things; it removes the burr and abrades away or "polishes" out micro scratches on the cutting edge and the bevel. Check out the last two blade images here: http://forum.tormek.com/index.php?topic=1689.msg7998#msg7998 
That is the blade before and after honing with compound. The micro burr and scratching has been removed by the compound.

Burr construction, shape and amount vary due to the hardness of the steel and how brittle it is, and forms differently depending on the coarseness of the abrasive used when sharpening.  Ever hear of a burr referred to as a "wire edge"?  That happens when the steel is pliable enough to actually roll over along the edge.   Here's a textbook example:



Not all burrs are the same.  Here's one where the burr material was extremely thin, and stood straight out from the edge.  It was so fine simply blowing on it caused it to wave around on the edge like little flags.



Honing with compound wears away the burr making it thinner and bends it back and forth causing metal fatigue until breaks and/or is torn off by the compound and wheel.  The time it takes to accomplish this depends on how hard and brittle the steel is, and how much burr material exists.

So, sorry, but the real answer to how long you should hone is; hone until you are satisfied that the burr has been removed to your satisfaction.  You can check for burr a bunch of different ways:  You can inspect the edge under a good, directional light and look for aberrations in reflection.  Use magnification.  Slice your finger perpendicularly over the edge and feel for it.  Drag the edge of your fingernail VERY gently along the edge and feel for resistance, or lack thereof.  Pull the edge across a cotton ball or some soft, easily snagged material.  Try the edges of different types of paper.  Be creative.  Try a bunch of methods and see what works for you.

Honing is most important at the cutting edge. A beautiful shiny bevel isn't good for much more than a case of the grins if there is still burr on the edge.  There is a big difference between a "toothy" edge and a rough edge caused by random piles of burr packed along the edge of the blade.

Burr removal is important, and you can imagine what happens if it's not removed.  The first cut with the blade will tear away some of the burr leaving it in the material being cut, but the rest will smash down and bend around the edge causing the knife to appear dull.  The idea of broccoli and burr has never sounded that tasty to me, even with added truffles and a mild, creamy Béchamel sauce.

Honing compound is actually an abrasive and cuts steel.  Honing longer will further polish the bevel by removing micro scratches, but further work on deeper scratches would be of diminishing returns.  I'm not really sure you can actually remove enough material to make the blade sharper, especially considering the leather is soft and may actually bend a little around the edge possibly dulling it if you hone too long.  Maybe somebody else has a better idea about that.