Thread: How flat is flat for a hone

Enigmatic!
Some time back I purchased a Chinese Hone rated as 15,000 grit. I had not used it, and happily so, when I discovered that one should check the flatness of their hones. Fortunately for me I possessed an engineers straight edge (used it to assure the flatness of an engine block and head for a proper fit). I laid the straight edge down on the Chinese hone--parallel to the long edge of the stone and noted that either end displayed light indicating that the central part of the stone was not flat, but rather convex. I contemplated the purchase of a flattening hone but opted for my table belt sander. With the straight edge, and patients, I finally achieve what I believe to be a perfectly flat "Chinese" 15,000 grit stone. The opposite side was the opposite. The edges were high creating a bowl like center. The process of eliminating the bowl center took as much caution and patients as the opposite side but with time and patients the bowl was eliminated and I created a hone "engineer level" flat.
The ease with which the stone was removed makes me wonder if the hone is truly a 15,000 grit. Since the stone was inexpensive the belt sander worked fine despite the finish using a 400 grit sand paper on a flat granite surface.
Anyone ever have the occasion to flatten a hone? How did you do it? How long did it take? What are your suggestions?

The newer you are to honing SR's the more Flat your hones need to be to eliminate as many variables as possible..

Learning to hone SR's is all about working through each challenge that is presented from the razor and the hone..

As you get better and better you tend to realize that the hands are better at working around minor issues in the Blades and the Hones so Pretty Flat and Very Smooth are good enough


ps: Numbers given by sellers about Natural Grit comparisons are basically WAG's at best and Marketing Hype at worse..

Every time somebody wants to doubt that I ask a simple question "How did you test the comparison"

Unless they used actual test blocks and a calibrated pressure stroke then it is simply a WAG

Here is why

Using a different media someone posted this years ago here on SRP


Same piece of stone, same piece of chalk, different pressure how you test makes a difference in the results





Make Sense now ??? :P

Obviously the upper chalk is the ebay Chinese 15k and the lower one is the ebay Chinese 3k. The fact that they are the same stone is just a bonus!

Originally Posted by Glock27

Enigmatic!
Some time back I purchased a Chinese Hone rated as 15,000 grit. I had not used it, and happily so, when I discovered that one should check the flatness of their hones. Fortunately for me I possessed an engineers straight edge (used it to assure the flatness of an engine block and head for a proper fit). I laid the straight edge down on the Chinese hone--parallel to the long edge of the stone and noted that either end displayed light indicating that the central part of the stone was not flat, but rather convex. I contemplated the purchase of a flattening hone but opted for my table belt sander. With the straight edge, and patients, I finally achieve what I believe to be a perfectly flat "Chinese" 15,000 grit stone. The opposite side was the opposite. The edges were high creating a bowl like center. The process of eliminating the bowl center took as much caution and patients as the opposite side but with time and patients the bowl was eliminated and I created a hone "engineer level" flat.
The ease with which the stone was removed makes me wonder if the hone is truly a 15,000 grit. Since the stone was inexpensive the belt sander worked fine despite the finish using a 400 grit sand paper on a flat granite surface.
Anyone ever have the occasion to flatten a hone? How did you do it? How long did it take? What are your suggestions?

I used in the beginning the Norton flattening stone. I then progressed to what I use now which is the DMT lapping plate. It is way more precise and works great. Every so often I simply use a pencil to make cross marks across the hone both vertical and horizontal. I then place under water and start to lap the hone. I stop every so often to see where the stone still has pencil marks and know that is a area that is lower than the area that is now missing the pencil marks. I continue until all marks are gone. I then do again and do a few strokes and if they all are removed simultaneously I know it is lapped to a degree that will yield great results.

There will be others to chime in on their method as well. Good luck.

AFAIC flat is where it's at ! ...........

Originally Posted by gssixgun

The newer you are to honing SR's the more Flat your hones need to be to eliminate as many variables as possible..

Learning to hone SR's is all about working through each challenge that is presented from the razor and the hone..

As you get better and better you tend to realize that the hands are better at working around minor issues in the Blades and the Hones so Pretty Flat and Very Smooth are good enough


ps: Numbers given by sellers about Natural Grit comparisons are basically WAG's at best and Marketing Hype at worse..

Every time somebody wants to doubt that I ask a simple question "How did you test the comparison"

Unless they used actual test blocks and a calibrated pressure stroke then it is simply a WAG

Actually I had to search for the estimated grit of the stone for it was not listed on the box. Sometimes we must simply have faith. My experience has shown to me that most business people are fundamentally honest. It is like how do I know .3 micron lapping film is really .3 microns? I don't I have to trust the company and the experience of others. When you go to a Doctor how do you know he can really perform a given medical procedure. Most do not graduate in the top 10%. Ergo I trust that the stone is a 15,000 grit on faith for I have no other why to measure that truth.

Originally Posted by Glock27

Actually I had to search for the estimated grit of the stone for it was not listed on the box. Sometimes we must simply have faith. My experience has shown to me that most business people are fundamentally honest. It is like how do I know .3 micron lapping film is really .3 microns? I don't I have to trust the company and the experience of others. When you go to a Doctor how do you know he can really perform a given medical procedure. Most do not graduate in the top 10%. Ergo I trust that the stone is a 15,000 grit on faith for I have no other why to measure that truth.

.3 micron film has 0.3 micron particles adhered to the substrate. The doctor you see has undergone education, examination, and continued certification qualifying him to do the procedure. Whether he graduated first or last in his class, he has to meet standards in order to be allowed to be licensed to practice. On the other hand, I can dig a rock out of my back yard, cut it to shape, and call it whatever grit I wish. NO natural stone has ANY justifiable grit rating and anyone selling one with a numerical grit rating is either ignorant or a fraud.

Your remark seems to be saying there are absolutely no stones which can be trusted regardless, natural or man made I am reading your logic to imply that one may as well just use anything to sharpen with and that producers and marketers are all liars about their product. Hm-m-m-m. This is a bit of jerky I can't seem to chew. I am sure it makes sense to you, no doubt, and maybe I am a fool, but I trust the producers to reflect there product to be accurate, or at least as accurate as they can determine. I certainly do not have the expertise to prove otherwise, and I have absolutely no idea what your expertise is. You may be an engineer for all I know. (How exactly do you know that 3M .3 micron film has .3 micron particles adhered to it? All I can do is have faith in the company and trust that they are truthful about their product. If not it would not be used by the optic industry to polish optics. Yep. I can make off handed remarks about a product, but my remarks are only going to be somewhat anecdotal; can't scientifically prove crap about it.
As for doctors. Which do you really want working on your heart or balls--top of the class or bottom of the class. As for me and my family I would really prefer the top of the class or at least as close to the top as possible (if I can afford him!"). Now, granted, just because someone has high marks in class does not qualify him or her for anything except maybe being smart. You can meet standards, but who set the standards and what exactly do we know about those standards, what are the quality of the standards? I know zero personally. I taught special education for 35 years and was certified, passed all my classes, received my diploma and certificate to teach then President Schrub decided that I was not qualified to teach despite my having a Masters in Education and 35 years in the classroom. I was going to be forced to go back to school to take some phony classes, or pay $250 to take a test to prove that I was qualified. What exactly are qualifications? I sure as hell believed I was qualified, 35 years teaching and a Masters. So who determines those qualifications. In my case it was the President who had no experience in special education. Wow!
As for stones out of the back yard. Yep. I have actually dug one out, kept it and flattened it (just for fun and experience) and actually used it to sharped knives with. It actually worked and I still keep it around though I don't use it anymore, except as a paper weight. Anyway, this is my personal testimony to the issue at hand.
Please note that I am merely making an observation here and not attempting to be argumentative. Certainly it must sound that way, but it is not what I intend.
With all due respect to you Utopian. Gday.

Sure makes sense to me