Thread: Japanese Nagura stone

let's set aside single macrocrystals. Jade and jasper are not single large crystals. they are composed of microscopic crystals as is novaculite.

Yes.... but a large rock of jasper is a large rock of jasper.... with a combined hardness harder than steel, so I don't see how the steel is going to keep refreshing the smaller crystals?

How can you honestly say that if I purposefully textured something that is harder than steel that somehow through use the steel would break it down into its smaller particles? That doesn't make any sense.

This is what I recommend you do to prove it to yourself. Get a hone that you don't mind scratching, the side of a norton for example, or the side of a natural. And take a blade you're okay with damaging, maybe a kitchen knife or a nail. Scratch the hone. Notice that the hone scratches (this means the steel is harder than the hone). Now take the knife and try and scratch glass, or if you have on hand, quartz jasper jade corundum etc. You won't be able to scratch it. You'll blunt the blade. This is called "Moh's test for mineral hardness" and is rocks 101. Even if you have a bonded stone with cutting particles harder than steel, if the stone is not harder than steel the bonds break and it scratches. the little particles are breaking off and you get grit based on these particle sizes. If the stone is harder than steel the particles will almost never break off.

Yes, water erodes canyons. Over how many hundreds of years? and many if not most canyons are in sandstone. Plus, that water is flowing continuously. And water can only eroded chemically. What does the eroding is all the SAND and ROCKS and PARTICULATES in the water. The water is constantly rubbing them, like sandpaper.

i dont need to test. i have novaculites. I understand how it works which is why such things make unreasonably pitiful hones.

perhaps you should sign up for experience 101

Originally Posted by khaos

Yes.... but a large rock of jasper is a large rock of jasper.... with a combined hardness harder than steel, so I don't see how the steel is going to keep refreshing the smaller crystals?

How can you honestly say that if I purposefully textured something that is harder than steel that somehow through use the steel would break it down into its smaller particles? That doesn't make any sense.

This is what I recommend you do to prove it to yourself. Get a hone that you don't mind scratching, the side of a norton for example, or the side of a natural. And take a blade you're okay with damaging, maybe a kitchen knife or a nail. Scratch the hone. Notice that the hone scratches (this means the steel is harder than the hone). Now take the knife and try and scratch glass, or if you have on hand, quartz jasper jade corundum etc. You won't be able to scratch it. You'll blunt the blade. This is called "Moh's test for mineral hardness" and is rocks 101. Even if you have a bonded stone with cutting particles harder than steel, if the stone is not harder than steel the bonds break and it scratches. the little particles are breaking off and you get grit based on these particle sizes. If the stone is harder than steel the particles will almost never break off.

Yes, water erodes canyons. Over how many hundreds of years? and many if not most canyons are in sandstone. Plus, that water is flowing continuously. And water can only eroded chemically. What does the eroding is all the SAND and ROCKS and PARTICULATES in the water. The water is constantly rubbing them, like sandpaper.

Now is this correct??? I thought water erodes by mechanical not chemical. If it was chemical wouldn't the water dissolve the sand??
Forgive me, I flunked chemistry. LOL

Sand is formed with covalentt bonds whihc don't dissolve. Things like lime is calcite which is ionic so it dissolves. If you were to have streams of deionized pure water it would be a pitiful eroding agent. You are correct in that water erodes mechnically, it picks up particles and grinds them together. The water itselsf does not cut anything. It can't.
KevinT I'm not gonna argue this any more. Yes, you can make a hone out of solid rocks with high mineral hardness. you just have to texture them.

A 10k stone will always be and cut as a 10k stone regardless of how it is lapped, however, it will not cut at the same rate nor have the same tactile feedback regardless of how it's lapped. A smooth polishing stone makes for much quicker work. This is evident when polishing large surface areas of steel.

As one final piece of evidence, how often do we have to lap bonded abrasive stones? How often do you lap a dmt (yes technically it is abrasive bonded to a surface, but for all practical purposes, it is a solid with a texture, and a hardness greater than steel)