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Over-Sharpening
#31
We're on a posting binge this morning (three so far). Our apologies for hijacking this thread into the arena of bulls and the reproductive act frequency thereof. Totally our fault. Whether it's "do or don't" for our good friend Max, we're still interested in hearing more about the theory of over-sharpening assuming that there is still something left to say.
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#32
I find it strange that fellow sharpeners (outside of this thread) keep asking me why at all would they over-sharpen or over-hone when the 2 planes of the edge meet at the apex anyway.
Fine sharpening is applying macro-forces to the microscale of the edge apex - too easy to overdo.
http://knifeGrinders.com.au
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#33
Mr. KG, there are WAAAAY more people who don't understand sharpening at all, compared to so few who can quickly and consistently whip out a sharp knife without any trouble every single time.

There is so much mis-information on the web, and it's hard to find the right info. Especially for newbs. They don't have a clear understanding, bless their hearts.
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#34
You sure have that right Mr. Mark!  I remember when I first decided to learn sharpening the amount of information/misinformation was overwhelming.  So many saying this is the true secret to knife sharpening, buy this machine and you’ll become a master, this way is the only way, this way is the right way, and on and on.  Just spend some more money on my machine and you’ll reach sharpening nirvana!  It seemed like sharpening was a like a secret society of voodoo black art masters that had discovered the true secret.

I think it goes something like this:

At first it’s really complicated and seems overwhelming.  Then you discover it’s really very simple; sharpen the blade then deburr it.  Once you figure that out and decide to really understand what sharpening is about, you can once again make it as complicated and overwhelming as you wish to make it.  

There's probably a life lesson in there somewhere. Rolleyes
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#35
(01-25-2018, 04:21 PM)KnifeGrinders Wrote: Fine sharpening is applying macro-forces to the microscale of the edge apex - too easy to overdo.

I totally forgot to comment on this, and I meant to... 

I think I may have picked up on things you've mentioned in passing. I understand you have the ability to adjust your angle to within tenths of a degree with your software. I know this is beyond my capability, even with the Edge Pro.  

When you're only hitting the edge of the edge, even the lightest weight is a concentration of pressure, resulting in macro-force on the edge of the edge, right?

This sounds familiar to the way I sharpen freehand. Intentional convexity, on the smallest scale I can possibly manage.

The key for me is to make sure I'm thinning the bevel one or two degrees thinner than where I want to finish, depending on how many stone progressions I have in mind. This way I'm not concerned with refining the whole edge, even though human error (and erring to the thin side), usually results in refining most of the edge. It's the Edge Of The Edge I'm concerned with.

It's a simple way of sharpening most efficiently. The fewest strokes wins. More strokes= mis-strokes= rounding the edge.

Finishing on a belt is different because you're always edge trailing, and the speed of the belt doesn't allow you to control the burr without refinement. Bare leather takes too long, and polishes the tooth. I think diamond compound works much faster. You can always add tooth after you have a clean edge.

This goes back to creating a burr, then controlled abrasion of the burr, only on the side with the burr, until you've gotten to the base of the burr. The result is a pretty clean edge, ready for a little distressing. 

"Flipping the burr" is basically a myth to my present understanding. Part of the burr will flip back and forth, but what is actually needed is total removal of the base of the burr from the side with the burr. 

On a belt, you will generally create a burr with the first pass. It's best to flip the burr so you have a clean, coarse scratch pattern on both sides. Additional flipping with the coarse belt is not only unnecessary, you're wasting steel. 

Now shut the machine off. You can remove the burr on a stationary belt, or better, on a stone of similar grit. It may feel like the burr is flipped after just a couple strokes, but if you look carefully with high magnification, you will see a shiny line on the edge with the burr. When you look at the side you think the burr has flipped to, you probably won't be able to see any burr. It will look like a perfect scratch pattern to the EOTE, but you may be able to feel a little burr, and assume the burr is flipped. That is misleading. 

As long as you can see a shiny line on the burr side, that means the burr is still there. What feels like a flipped burr is only the flimsy end of the burr. You must remove the shiny line on the burr side Completely. The shiny line is actually the burr. You need to keep working on the shiny line until it looks like a Perfectly clean scratch pattern all the way to the EOTE. 

Now you are getting very close to a clean edge, but you haven't made a single stroke on the side without the burr, so you haven't wasted any time, and haven't encouraged burr Growth.

Now, it should look very much like a clean scratch pattern on both sides. Maybe there is a little crud on the EOTE looking from both sides. This is where distressing comes into play, but you have to be careful. I don't think it's a good idea to simply "make a slice" on something (like wood or plastic). If you do, the metal crud will build up on the front of the slice, and you'll be dragging the rest of the edge through the crud. I like to use a sharpie, and roll the sharpie Away from the edge as I drag the sharpie along the edge. Make a couple passes. As long as you aren't dragging the edge through the crud you're distressing properly. 

Here is where I intentionally raise the angle very slightly. Slowly and carefully remove the dangling crud with an edge leading pass on each side. Distress and repeat. That should do it. 

I'm not saying "This is how it is", I'm saying, IMHO. YMMV. Especially according to refinement.
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#36
Mr. Mark, you bring up some very interesting points and one that that I had not even thought of.  Thanks!

That shiny line at that base of the burr… I’m very familiar with that, and I hate it when I see it.  It’s always a problem to remove.  It’s always just on one side, and if the blade is flipped it appears to be completely deburred on the other side.

You then said, “controlled abrasion of the burr, only on the side with the burr, until you've gotten to the base of the burr. The result is a pretty clean edge…”  

I had never even considered burr removal from only one side of the blade, but it actually makes sense. (slaps forehead).  Looking at the other side of the knife there is no visible burr, so it kind of does make sense to not attack the burr from that side.

The only question I have is that sometimes the burr gets bent over to the other side when I’m trying to remove it.  But then, maybe it’s as you suggest, that what’s getting bent over is just the flimsy top of the burr and not really important.  

I don’t like deburing on plain leather because it burnishes and smoothes a toothy edge.  I don’t like using compound because it abrades away a toothy edge.  The thing is that I WANT to be able to deburr on the Kally, but over and over you guys keep talking about hand deburring.  I find that very annoying, Smile  but I’m starting to be convinced that may you are on to something there.

Very interesting stuff Mr. Mark.  Cool post.  The only thing I don't like about your post is that it made me think, and that's not fair because nobody ever told me I'd actually have to think!
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