When I took woodworking classes, we were taught that you could not achieve a flat surface with only two stones. My (sad) experience is that was true.
Mike
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When I took woodworking classes, we were taught that you could not achieve a flat surface with only two stones. My (sad) experience is that was true.
Mike
Go into the world and do well. But more importantly, go into the world and do good.
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With Japanese tools, a big deal is made over flatness on the stones, especially for plane blades.
Any out of flatness is registered on the blade as you work up through the grits- an even polish on one stone will often show as slightly convex on the next finer one. Getting the polish out to the edges on a 10k stone after the 8k one (the 10k only occasionally for show/vanity really) cannot be more than a few microns. In spite of trying to use the surface evenly, I don't recall ever seeing any be convex, but that's only over 40+ years.
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It should be obvious to anyone that if you rub two water stones together until the surfaces are completely in contact that you will have two conforming surfaces. It is not at all obvious that those two surfaces will always be flat. Anyone who believes that, please explain a process that will always lead to two flat surfaces from rubbing two initially non-flat surfaces together.
Mike
Go into the world and do well. But more importantly, go into the world and do good.
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You might need to try it yourself, to see if your theory holds up in practice.
I'm sure it's possible to get the result you're talking about to prove the point, but it would take some work.
In the mean time, lots of folks will have flat stones and sharp tools without issue.
Contributor
I have experience with the two stones not coming out flat. That's how I know - from experience - that it won't work.Originally Posted by Cameron Wood
If it were possible to guarantee two flat surfaces by rubbing two non-flat surfaces together, the technique would have been implemented in industry.
Mike
Go into the world and do well. But more importantly, go into the world and do good.
Contributor
If you place one stone on top of another and work it back and forth lengthwise, you will end up with two stones that mate and are not necessarily flat. If one is concave, the other will become convex.
If you pay attention to what is taking place it is possible to work the stones at different angles to each other and produce two flat stones. It isn't a matter of counting strokes or magic formula. It is a matter of paying attention, aligning the stones for optimum removal of high areas and checking results.
I've worked stones flat by having one 90º to the other and moving it back and forth and side to side to remove a concave center area of the stones.
jtk
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)
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Also not possible to guarantee a sharp tool by rubbing it on a stone, or a flat board by shaving it with a hand plane.
[OP]
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Gents, I appreciate all of your input. After considering your combined wisdom, I am going to replace my old diamond plates with new diamond plates. I prefer to use my remaining time I have for working wood, not flattening stones, Thanks again.
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My best friend and I ground telescope mirrors by hand when we were teenagers. Making an optical flat was much, much harder than making a much larger primary mirror with a parabolic surface. For flattening sharpening stones, these days I'm using Atoma diamond replacement sheets on a granite surface plate that are larger than the stones flattened. With an abrading surface larger than the stones on a known unyielding flat surface, it's not hard to make sharpening stones truly flat quickly, and I understand what truly flat is.
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I wanted to add one more idea for flattening. It’s a 4”x10” CBN flattening plate for $100. I have not tried this myself, but saw it in someone’s YouTube. LINK
"All that is necessary for the triumph of evil is that good men do nothing."
“If you want to know what a man's like, take a good look at how he treats his inferiors, not his equals.”
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Perhaps not applicable to ceramics, but early on in choosing a sharpening method, the whole ritual of flattening the waterstones seemed pretty inefficient to me. Keeping oilstones, like India or washitas, flat is not that difficult. One just needs to keep in mind wearing them evenly. Sharpening free hand makes it natural.
If the sharpening media stays fairly flat by just using them "properly", this whole notion of needing accessories to keep them flat becomes a non issue. Wondering about needing two or three stones to achieve flatness also becomes a non issue.
Member
Probably a good idea given that you are happy with your diamond plates.
If you do decide to try a water stone, I would probably go with a Naniwa Chosera or a Shapton Professional or Glass stone, and I wouldn't go below JIS4000. The idea would be to complement what you have already instead of replacing it. One of your old diamond plates would do fine for flattening.
So far, my own opinion on diamond plates is that they are great for more coarse work, but the stray large abrasive grains can leave scratches that are hard to polish out when you get to finer grits. Probably not such a problem with knives, as an edge with a bit of tooth can bring a lot of slicing aggression where a very keen but polished edge tends to skate on cuts instead of biting. Those stray scratches aren't as good on woodworking tools used for push cutting.
Quality stones, especially the higher grit polishers, tend to be harder and don't need as much flattening, where coarse water stones are often pretty soft. Ongoing stone maintenance is a 1-minute proposition on these, so long as wear is not allowed to get out of hand. You've already got old diamond plates, so no need to spend more $$$ there.
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