A sharpening Enigma-does this happen to you too??

dePaul

dePaul

Joined
Aug 8, 2000
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The other day I sharpened my Delica to the point that it was shaving my armhair quite easily. I put it into my drawer to use it the next day.

Well, next morning I grabbed my Delica and opened it once again just for the pleasure of doing some additional shaving. To my surprize, it did not!! In fact it was almost dull. There were no marks on the edge and the previous day, I closed the knife very carefully.

The funny thing is that it´s not the first time this happens to me :(

I wonder if this maybe is a matter of atoms doing some regrouping?
 
I have never had that happen to me.
The one I can't figure out is when you thumb test the edge and it doesn't feel particularly sharp, but the hair literally jumps off your arm.

Paul
 
Originally posted by dePaul


The funny thing is that it´s not the first time this happens to me :(
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Maybe a dumb question, but are you the only one who uses the knife and knows where you hide it? Maybe your wife is shaving her legs with it when you're not looking - no offense intended to Mrs. dePaul. :)
 
Originally posted by shane45-1911


Maybe a dumb question, but are you the only one who uses the knife and knows where you hide it? Maybe your wife is shaving her legs with it when you're not looking - no offense intended to Mrs. dePaul. :)
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ROTFL :p

I second Paul's suggestion - that's happened to me more than once!

DePaul - is there any chance that the edge is hitting the lock bar?

Matthew
 
This is a mystery to me, too, but I've heard that something similar happens to a steeled edge. It can be sharp immediately after steeling, but less sharp the next day. It's hard for me to understand how that could happen, but apparently it does. Maybe there's something about your sharpening method that has the same effect on your blade.
 
For straight razors they say to let the blade rest after honing use your leather strop before using. I guess that the edge can move around some after sharpening. I notice it more with some stainless alloys. So my suggestion is to see what happens if you strop your "dulled" edge.
 
dePaul,

I'd ask if you have April's Fools over there in Sweden...
...except that it happened once to me, too.

I usually attribute it to misjudgements in perception.

-Jon
 
The knife buying public, by and large, now demands that knives are sharp enough to shave, but it is actually a bad edge to put on a using knife. The geometry of most "usuable" blades (by this I mean not X-Actos or razors)means the only way to get the knife "hair popping" is to build up the wire edge AND LEAVING IT! When the knife is used at all the wire edge bends over & the knife is again dull. Darrel tells me that he tried for the longest time to put functional edges on his knives, and constantly got complaints from customers because "it doesn't shave".

In Darrel's words, "when you touch that edge to anything, it is done."

This problem has bled over (pun intended) to those of us that sharpen our own blades, thinking that shaving is the ultimate test. I made Darrel put his money where his mouth is and asked him to put a "real" edge on my Arc-Lite. He did, and while it wouldn't shave it is the best cutting, most durable edge I've EVER had on a knife!

I think we need to move away from "hair popping" to more real world edges. I hope this helps.
 
I'd second that.
I've put a shaving edge on my F4 by hand before, but the edge doesn't last all that long.
When I got my gatco and resharpen that blade, it doesn't shave well, but it cuts like a tiny monster (relatively speaking of course, i'm no sharpening master).
I'd say your problem is probably a wired edge that just got rolled over after used...
 
I do most of my finish sharpening with either a Washita grade Arkansas stone or medium Spyderco ceramic. They don't always shave real good but they cut for a long time.

Paul
 
I've had this happen also. What I find more frequently is that I'll put a scary sharp edge on my EDC (small CS voyager), and one cut through a poly rope (1/2 inch), and it doesn't even shave.

Hmmm. I was blaming the AUS-8, but it might be the wire edge....

Time to get the flashlight out, and do some investigation.
 
I have to take issue with Ghen and some others. I am by no means a professional bladesmith or sharpener, but I am taking the performance portion of the test for my ABS journeyman stamp this month. Part of that test is to make a blade that will shave, cut through a 1" free hanging manila rope, chop through two 2x4s and still shave at the end. I have been able to do this no problem. In fact, in my last practice test, my teacher had me go through three 2x4s just to be sure--still shaved.

Ghen is right; that this would not be possible with a wire edge. But we are very careful to establish a wire edge and then remove it completely. Following the recommendations of Wayne Goddard and Ed Fowler, and Ed Caffrey (I think Jerry Fisk uses one too), this is done on a Norton Fine India stone (320 grit). This stone is rough enough to produce an agressive or "toothy" edge, while smooth enough to shave no problem. All in all, this method is a good compromise.

John Frankl
 
That used to happen to me until I learned to finish with light pressure on the hone and strop -- I end each stage of sharpening with a few light strokes. When you use heavy pressure you're bending the edge as much as grinding it, and it'll bend back. Light pressure makes shallower scratches, too, for a smoother transition between stages of polishing.
 
This used to happen to me sometimes. I'd work on an edge and get it shaving sharp, then store it or carry it. When I'd try to show friends what a great edge I had, it wouldn't shave. What always puzzled me was that I'd not used the knife for much of anything. I used to theorize that the very fine edge was corroding (nuts, huh?). What I've now realized is that I was stopping with a wire edge. Since I've never been good at feeling it with my nail, I now use a 30x scope to make sure with bevels meet, that the texture is right and that there is no wire edge.
 
ghen :

The geometry of most "usuable" blades (by this I mean not X-Actos or razors)means the only way to get the knife "hair popping" is to build up the wire edge AND LEAVING IT!
Click to expand...

Quality knife blades can be taken to shaving sharp and used for a significant period of time before losing this sharpness. Shaving ablity is strongly dependent on alignment just as much as polish, you can shave with even really coarsely finished blades. If your knife can't shave then the edge is just poorly aligned because the sharpening was sloppy.

The reason that coarsely ground blades don't need to shave to cut well is that there is a stronger overlap in the cut path of the micro-teeth because they are larger. This just means that you can get sloppier the rougher you grind. You don't have to however, and if you don't you will get a better cutting blade, regardless of edge finish.

Sal Glesser also promogates this myth of a wire edge when he talks about sharpening straight razors. Properly sharpened straight razors (or anything else) do not need, or would in any way want to have, wire edges. You can see direct evidence for this in Lee's book on sharpening as he has pictures of the edges of highly polished tools under heavy magnification, and yes they would all shave very easily.

You can also do a net search for "Scary sharp" and read about various wood workers sharpening chisels to very high polishes, long past simple shaving sharpness. The edges are not weak, in fact they are the optimal condition for durablity and performance for push cutting. This is the way axes are sharpened, and they take much higher impacts than knives.

In regards to edges becoming dull if left alone, this will happen if you finish with an aligning step such as steeling or even using a smooth ceramic rod. I have verified this by checking the sharpness by cutting light thread which can detect very small changes in edge performance. You can readily see degredation as the edge steels back to a relaxed state. The same thing happens as well in regards to blunting, an edge will "self-sharpen" if you let it relax after use.

-Cliff
 
Yes I over-simplified some of my points for the sake of brevity. I realize that there can be a true edge and have it shave, hair pop, whatever.
 
I'm pretty sure you were simply shaving with the burr (really fine burrs are also called "wire edges"), which then bent. This used to happen to me regularly, and there are ways to stop it.

First, you have to be sure that it's happening. There are three decent ways to check for a wire edge:

1. Rub your thumb gently off the edge, as if you were rubbing dust from it. Do this on both sides. A burr will feel more aggressive on one side.

2. After you shave hairs using one side of the knife, turn it over and shave with the other side. A burr present will cause the knife to shave better on one side (the side with the burr).

3. Look at the edge under magnification, with a very bright light shining at the edge. You should be able to see the burr.

I have had wire edges so small that they defied all of these tests, however. What it meant was that I had developed the wire edge, then used *extremely* soft strokes on the hones to straighten the wire edge. It shaved equally well on both sides, and I could feel no burr. But a straight burr is just as weak.

To get rid of a burr there are several things you can do:

1. Strop the edge. This is the easiest method, and will leave you with a nice, smooth edge. I use the polishing tape that's available for the Edge Pro, and it works well too. 1000 grit sandpaper on wood is also a cheap option.

2. Keep raising your grits, and soften your strokes. This takes a really long time, by the way. Otherwise, you'll just be straightening the burr.

3. Make the angle you sharpen with more obtuse, and use soft strokes. So, if you just sharpened a 20 degree edge, raise the angle to 22 or 23, and with *very light* strokes sharpen for a while longer.

Steeling with not remove a wire edge, it will only straighten it. I've had the best results with polishing/stropping, as this not only removes the burr but also give me a nice edge that will last. Once the burr is really gone, you can go back and roughen the edge (micro-bevels work rather well) using a few light touch ups on a medium stone.
 
Shane45-1911, there is no Mrs dePaul. I am a lucky man...

Starfish, no the edge is not hitting the lock bar.

Lurker, I am not steeling my knives.

biogon, untortunately, this is not an april joke :(

ghen, Cliff and JohnW, thanks for the interesting tips. Most useful!
 
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