Flatten your Stones... or not?

If free hand introduces convex bevel due to hand wobble, probably the dished stone helps compensating that effect. I imagine anyone doing long back & forth scrubbing motions tend to tilt the spine higher near body and lower the farther the hand is. Try not locking the angle, our habd will naturally lift the spine when it’s near body, sharpening with edge out. The curvature of the stone will definitely help compensating the rocking motion. :cool:

On the other hand, if one can master no rocking free hand, the dished stone will yield convex apex that makes a ‘stonger’ apex, or so they say :p

Lastly, if one has Martin’s consistency and ability to feel the bevel being flat to the stone, such curvature will not matter. It’s going to be flatter bevel compared to my results. :thumbsup:
 
I had a washita stone gifted to me that wasn't finished. It had several waves running across it's surface. I tried to use it to sharpen kitchen
knives but without success. Then one day I took my coarse diamond to it and leveled it. Then tried it and had success. I suspect what Cliff
was saying has some truth.
In my meat markets I see stones just like the Japanese man's stone. I have tried to sharpen a knife on it and it was difficult. I had to utilize
the ends in order to get a decent edge on it. Still, for me maintaining a flat stone gives better, quicker more consistent results. DM
 
David Martin said:
It had several waves running across it's surface.
...maintaining a flat stone gives better, quicker more consistent results. DM
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A stone with waves on its surface would cause me some problems too. It might be good for sharpening darts or fishhooks, but pulling a kitchen knife across it would be something else.
If I have a choice, I do prefer a flat stone when working on knives that have straight or slightly smiling edges. I can work myself into a trance, don't have to pay quite as much attention to the area of stone I'm using and can listen to more complicated topics on the radio while sharpening. However, concave stone surfaces can, with skill, produce fine results and I would not toss one for that reason only.
 
Novaculite said:
...............SNIP........................... However, concave stone surfaces can, with skill, produce fine results and I would not toss one for that reason only.
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When I was a young boy, I worked after school in a delicatessen. The owner used the inside of a large stoneware crock to keep his knives tuned up. The natural curve of the crock would maintain a constant angle when the knife was pressed up against it. He was able to slice almost transparent slices of smoked salmon with ease!

Last week, I bought a 'razor blade hone' from E-bay. It's made of glass, and looks like half of a coffee mug laid on its side. I suppose Grandpa used an ordinary mug too... Just take a double edged razor blade and press it against the inside surface of the mug and rub it around and around. Again, the constant angle gets the job done.

Perhaps, there are times when that concave surface can be as effective as flat surfaces.


Stitchawl
 
stitchawl said:
The owner used the inside of a large stoneware crock to keep his knives tuned up. The natural curve of the crock would maintain a constant angle when the knife was pressed up against it....Perhaps, there are times when that concave surface can be as effective as flat surfaces.
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Did that shop owner, to keep a constant angle, have both the spine and the edge pressed to the inside of that crock? If not, and in order to keep that angle, he would have to constantly adjust his wrist to the inside curve. If the spine and the edge are pressed into a curving surface it will resemble the constant angle we have when honing a straight razor on a flat surface. Thanks for that story, never thought of that.
 
I appreciate threads like this. I like to keep my stones flat, but this helps to keep everything in perspective. Knife sharpening is a necessity for me for keeping the knives I use sharp, but also a hobby because I enjoy it and enjoy trying to get the best edges I can and experimenting with sharpening mediums and techniques. We could all get by with sharpening on dished stones if we had to.
 
ecallahan said:
I appreciate threads like this... We could all get by with sharpening on dished stones if we had to.
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So do I, and yes we could. My son lived in China for a while and sent me a photo of a man from a tiny village way out in the mountainous west. He had two knives, hand-made, extremely sharp, was mighty proud of them, and showed my son how he sharpened them: Maybe three feet off the bank of the stream that flowed by the village there was a large rock, probably some kind of sandstone, surrounded by more rocks that kept his feet out of the surrounding water. He'd jump across that yard of water to get to his rock, then sharpen his knives on it while down in a crouch. Judging by the looks of it, he was the latest in a series of countless generations that had used that rock as their only sharpening device.
 
I lack the skills to sharpen a knife to razor level on an uneven stone so I flatten my Shaptons and Naniwas each time immediately after use, still wet and with slurrie. With a diamond plate it takes fifteen to twenty seconds and the stones end up perfectly flat and smooth.
 
Novaculite said:
Did that shop owner, to keep a constant angle, have both the spine and the edge pressed to the inside of that crock? If not, and in order to keep that angle, he would have to constantly adjust his wrist to the inside curve. If the spine and the edge are pressed into a curving surface it will resemble the constant angle we have when honing a straight razor on a flat surface. Thanks for that story, never thought of that.
Click to expand...

Exactly like that! He held it by pressing his fingers on the blade, one up near the handle and the other mid-way down towards the point. He didn't swirl the knife completely around the crock, just back and forth covering about half of it. He never spent more than 10+/- seconds per side, and would do this 2-3 times during the course of the day. The spine and the edge were the only areas touching the ceramic crock. I've occasionally done the same with a pocket knife's Wharncliffe blade using a coffee mug. The technique doesn't work worth a damn on a recurve. :)
 
On the recurve portion I bet not. Sharpening on that Crock would leave a fine edge. Probably more fine than our sharpener doing house calls. The knife's edge he is checking looks to be flat grind gone convex. But this could all be just a line of 'crock sharpening'. DM :)
 
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Most of the knives that he worked with were typical Japanese single-bevel blades. I used to watch him work when he'd park in front of my building. He's spend no more than 5-8 minutes working on a blade, using two different stones. Usually a dozen or more of the housewives would give him one or two knives to sharpen, and he would just dump them all in a pile at his feet. I never knew how he was able to keep straight which knife belonged to which housewife, but he'd just bend down, pick through the pile, and the housewife would go away satisfied until the following month when he be back around.

When I first saw him, he was using a push bike, with his stones and water tub on the back. Over the years, he eventually made enough money to buy a used motor scooter and mounted his gear on that!
 
On a single bevel edge I can see spending that amount of time. But piling them out on the ground and picking thru them and handing them to the correct housewife. -- I could not do. And invariably I would nick the blade on one. Then she would not like it and I'd have to do it over. O- joy. DM
 
The vendor in Mexico I remember seeing used a 3 wheeled bicycle. With a 2' X 2.5' wide box on the back axle. That he kept all his stones and sharpening items in. He had a leather strop and I don't recall any slurry being on it. He would sing his chant, pull up in the Plaza, get off and
open the box and set up his stones on the lid. People strolling about the Plaza and shop keepers would come and hand him their knives and wait, talking among themselves. As he finished each knife he laid them in a row on the upper part of this box. When people saw their knife in the row, they stepped up, picked it up, felt of it and handed him the dinero. He had a worn leather pouch he put it in. He would stand there in the sun for hours, not talking just sharpening. This is not the cooler climate of Japan but the 30 parallel where it gets hot at midday.
One would find out quick whether they are cut out to make a living sharpening. DM
 
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Hi,
speaking on wasting money by flattening stones,
cliff said of bester 7000, even with agressive flattening experiment, it had at least half a million passes lifetime,
so bester $59/500,000 = 0.01 cents, that means it takes ~100 passes to spend 1 cent
but if the stone costs $700 like some naturals which may have more or less lifetime,
then its like 14 cents per 100 passes
some folks need flat some dont
 
Thanks for these figures. They put it in a clear perspective. I'll bet I get more than that out of my Norton India and I gave half that for it.
Different figures for my JUM-3. DM
 
Keeping a stone flat by working the high spots during sharpening > flattening a stone when it becomes noticeably dished > flattening a stone every time you use it > never flattening the stone.

Most pragmatic sharpeners will probably find themselves doing the first option until the stone develops a noticeable dishing in spite of their efforts, and then lap the stone flat again and go back to working as much of the full surface as possible. The obsession with extreme flatness is mostly wasted effort beyond a certain point, especially with soft stones, as the very first stroke on the stone will take it out of flatness to some degree, and that amount is often greater than the flatness those individuals are trying to ensure each and every time. If it's eyeball-flat that's typically more than good enough, though of course exceptions exist.
 
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