Thread: How flat is flat for a hone

I am noticing that my remark seems to be over looked, or missed.

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 am new to this...so take my comments with a grain of salt. I have been flattening my stones with 3M 400 grit wet/dry sandpaper. I have one of those flat glass top stoves...so I pour a bit of water on the stove top, "attach" the sandpaper through surface tension and off I go. It works great...and it is inexpensive.

Originally Posted by Glock27

I am noticing that my remark seems to be over looked, or missed.

It's just very hard to read because you wrote it as all one paragraph. Keeping the attention of a forum reader is not easy.

You say that you trust the manufacturer about their product..

Let's start with

1. It's from China without getting into too much when have they given a "s**t" about quality if it makes them a quick buck?

2. They aren't qualified to figure out grit ratings... I am highly skeptical they've got a team of engineers or scientists on this. The stone is cheap as anything.. and if they were qualified to determine grit ratings they especially would be foolish to give a grit rating to a natural stone because giving natural stones grit ratings is just not possible.

So while CNAT hones can give you a great shaving edge it's hit in miss in quality and it's not a 15k..

Utopian is not lying to you... I hope you realize he's got more experience then a lot of us here. He's tried all these stones and knows a thing or two. No natural stone can have a grit rating. The either sharpen or polish or do nothing at all. Just a crap shoot with naturals. You get what you get..

On to flatness. I would lap my hones flat.. I used to more so then I do now but most coticule guys think lapping is a once in a while thing. Flatness is important!

I'll try again. Synthetic hones are made with a grit that has a size designation. There are different scales used so there is not a direct correlation from one scale to another, but in the range of hones we use, they are in the same ballpark.

Natural stones are not man made. No particular size of grit was used in the stones' manufacture because those stones were not manufactured, they were mined, dug up, or picked up off the ground.

Coticules have been used since the time of the Romans. They have no grit designation.

The Escher company took thuringian hones and judged them for their utility but labeled them according to their color, but not their grit designation.

The Japanese hones are identified by what mountain they were mined from, what color and pattern they have, and some surface characteristics, but not their grit designation.

Any natural hone that has been around for more than 10 years has no grit designation.

There is a reason for that.

Natural stones, or hones, have no grit designation.

I'll dig up THIS THREAD again, just for fun.

Great Idea. Is this American ingenuity, or human ingenuity. I really like this.

Thanks Utopian. I would appreciate it. Added information is critical. And it keeps harmony. Love you Utopian.

Originally Posted by Utopian

I don't honestly believe that I will succeed in altering the designation of what I have been calling the Chinese hone.
-Utopian, 2009

At least you were honest with yourself, as it looks like the grit designation stuck around. I am fond of PHIG, as it describes to me exactly what the stone is... and there's some humour there. Thanks for the old thread, I enjoyed it!

Originally Posted by Glock27

Anyone ever have the occasion to flatten a hone? How did you do it? How long did it take? What are your suggestions?

Maybe just a matter of caution, but I lap/flatten every stone I come across. I've never used a belt sander... but I suppose if a stone was really out of whack it would work. I use a diamond plate or a flattening stone. The amount of time it takes depends on how hard/soft the stone is, and how out of flat it is. As you say "engineer level flat" is certainly flat enough. I am pretty new to honing razors, so fair warning- I speak from the experience of knife sharpening here.

Originally Posted by Whizbang

I am new to this...so take my comments with a grain of salt. I have been flattening my stones with 3M 400 grit wet/dry sandpaper. I have one of those flat glass top stoves...so I pour a bit of water on the stove top, "attach" the sandpaper through surface tension and off I go. It works great...and it is inexpensive.

My wife would literally shoot me in the head! Good for you and glass is a great way to go.

Adam

Originally Posted by Whizbang

I am new to this...so take my comments with a grain of salt. I have been flattening my stones with 3M 400 grit wet/dry sandpaper. I have one of those flat glass top stoves...so I pour a bit of water on the stove top, "attach" the sandpaper through surface tension and off I go. It works great...and it is inexpensive.

Grit from the hone and excess grit from the paper will, in time, make the stove top look like a old blackboard around where the paper was!
~Richard