Thread: experiments

Note that the picture with the ruler looks much different than the picture above it. Evidently the position of something varies from picture to picture.

Originally Posted by Quick

Note that the picture with the ruler looks much different than the picture above it. Evidently the position of something varies from picture to picture.

Ah. This is only my opinion/impression from looking at the pictures and reading the text. The photo with the ruler is not meant as part of the continuum, only provided for a better sense of scale. The relative comparison is the progression from 12k to nakayama.

I'm certainly not an expert but FWIW, having been around about a year and having read a lot of threads, I don't even worry about removing scratch patterns completely from one hone to another. Taking what I interpret to be Lynn's lead "less strokes are better".

Maybe I am misunderstanding it but how many hundreds of strokes would I have to do to get a totally smooth edge leaving only 30K scratches ? When the TPT tells me it is sharp enough and the hairs on my leg pop effortlessly I test shave and pay no mind to the state of the scratch pattern. Am I in error here ?

Originally Posted by JimmyHAD

I'm certainly not an expert but FWIW, having been around about a year and having read a lot of threads, I don't even worry about removing scratch patterns completely from one hone to another. Taking what I interpret to be Lynn's lead "less strokes are better".

Maybe I am misunderstanding it but how many hundreds of strokes would I have to do to get a totally smooth edge leaving only 30K scratches ? When the TPT tells me it is sharp enough and the hairs on my leg pop effortlessly I test shave and pay no mind to the state of the scratch pattern. Am I in error here ?

I think you are missing the point. It isn't an article on how to sharpen. It's only some pictures that demonstrate a method to determine the equivalent grit size of a given natural stone. So I thought for those who like to look, similar comparisons could be done at home. Coticule is 8000? you can test on any steel piece you'd like

Both Mr. Parker and JimmyHAD questioned the time / strokes required. enlarging the photos of the second link in the post, i can read... it calculates to 80 lineal inches of stone by my reckoning.

it's not a debate of pressure / no pressure

You're correct. It is a comparison of the grit size and the resulting depth of the scratch pattern. He is implying "how smooth of a surface/edge can you get with the compared stones". He uses pictures of the scratch patterns to come to a conclusion. What Bart is pointing out is that the pictures are not valid for comparison. The unhoned surface in the pictures appears completely different in the two pictures used to compare the honed surfaces.

Quick,
In what ways they look different to you?

Originally Posted by JimmyHAD

I'm certainly not an expert but FWIW, having been around about a year and having read a lot of threads, I don't even worry about removing scratch patterns completely from one hone to another. Taking what I interpret to be Lynn's lead "less strokes are better".

Maybe I am misunderstanding it but how many hundreds of strokes would I have to do to get a totally smooth edge leaving only 30K scratches ? When the TPT tells me it is sharp enough and the hairs on my leg pop effortlessly I test shave and pay no mind to the state of the scratch pattern. Am I in error here ?

Not if you're just interested in shaving.

But if you're interested in comparing scratch marks from various hones then it helps to make sure that you've got the light consistent across shots. And it helps to use a high resolution microscope. And it helps to make sure that the scale of the scratches you're seeing correspond to the expected scale of the abrasives you claim to be testing. None of which seem to have been done here. A human hair is roughly 120 microns across, which would mean that the scratches from a 30k Shapton would be at most 1/250th that width (in practice they'll probably be even smaller, because the abrasive grain doesn't seem likely to cut to full depth unless you're using some pressure). So unless the ruler in the original photo is micron scale, those scratches are more likely from a hone somewhere in the 1000 grit range.

Now I would expect that the Nakayama would change the appearance of the bevel, both with the naked eye and under the scope. For one thing the Nakayama creates a slurry of clay and abrasives, which means that the abrasives will create a different scratch pattern that will change the reflectivity characteristics of the blade. For example simply leaving a more matte finish will obscure the scratches because the matte finish scatters the light more, which reduces the contrast. And my Nakayama does leave a more matte finish than my 30k Shapton. Also, the slurry will slosh through those large scratches and abrade their inside surface enough to change the reflectivity there as well, not just the high points on the bevel, while the Shapton, which doesn't form a slurry that I've ever noticed, only touches the high points at the tops of the grooves.

Personally I think the Nakayama and 30k Shapton achieve fairly similar edges. But I don't think these photos even begin to show what the OP in the linked thread claims they do.

BTW it appears that the OP in the linked thread has changed his photos and gotten rid of the incriminating ruler shot, though the new photos still have the other problems.