Craftsmanship in Wood

Brian, could you clarify what you mean by "the clamshell"? A slight convex shape? I can usually tell when this is happening by a band on the edge getting a brighter polish than the rest of the bevel. Caused by my rocking the chisel on the push stroke, I assume.

It's a tapering convex shape, where it becomes increasing convex as it nears the edge. My mortise chisels, for instance, are purposely done like this, but my hope is that a sturdier cutting edge will allow me to use a flat bevel so that I can better ride the bevel into the cut.

Same thing here, I chop bevel down sometimes to maintain a higher degree of control, and a flat bevel is easier to use in that way.

Chopping down across the grain like cutting haunches and stuff like that it's probably better to have a clamshell edge as that operation is very hard on the chisel and does not require self jigging on the bevel.

Next time I post an update on this thread I should have a good update on my progress. I will have another stone on the way soon and improved way to develop slurry on my Shinden stone.

Working to reduce the lines seen on the final finish and improve how quickly I see results.

This is a bit of chasing the horizon but I want to get this nailed down and have wanted to for a long time.

Looking good. Believe me, that horizon gets increasingly further away the more you get into natural stones. My small quarry's worth will testify to that.

Presuming your Shinden is flat and free of any toxic inclusions, those lines are probably streaking resulting from the stone not yielding slurry. Generating slurry and progressively lightening your pressure should help. If you haven't already, you might also try lapping the stone's surface. Old stones often have a hard oxidized layer that can be a bit scratchy. Revealing fresh stone can make a world of difference.

Looking forward to seeing your next results.

That's possibly the case here in addition I'm using a nagura, and it's now my understanding that the downside of a traditional nagura is that the particles from the nagura will also break off and they will be in the slurry, typically the nagura is rougher and so the slurry is then also rougher, leaving random streaks.

So moving forward to an atoma plate in 400 and 1200 to change this and improve the level of flatness on the stone. The DMT plates have been quite disappointing in this regard. I have an old one with a plastic base that's latest me 15 years and a new one with a steel back that I really dislike, even though I'm sure it's more accurate than the plastic one.

Seeing as you're using it on a suita, the nagura is almost certainly a problem. Nagura are typically not used on suita, as the nagura particles tend to collect in the su (the holes that give suita their name). The collected particulate acts in aggregate and leaves those large scratches.

I suspect you will be much happier with your Atoma plates than you have been with the DMTs. They should be flatter, lighter, and much less sticky when flattening. This is controversial, but I would caution against raising a slurry with a diamond plate. Even fairly fine diamond plates will leave comparatively deep scratches in the stones, yielding a surface of peaks and valleys. The diamond-lapped stone will behave as more coarse than it is, due to those peaks cutting more deeply than their abrasive content alone. Generally speaking, natural finishing stones work best when their surface is as smooth as possible, introducing the most surface area to the blade. The peaks of those scratches can also break off in chunks, again leading to scratches on your blade. I know that So suggests using an Atoma 1200 for raising slurry, and that is as coarse a diamond-lapped surface as I would ever sharpen on. Even then, if you are looking for the best finish, I would follow up with a bare stone.

Also, this is an interesting read regarding the concept of slurry breakdown: https://scienceofsharp.wordpress.com/20 ... reak-down/. It's something I've often questioned.

If you don't lap with a diamond stone, what do you flatten with?

My nagura has been relegated to display only it does look cool.

I appreciate the insights, do you lap two stones flat then use them to burnish one another? Sorry a bit confused...

dmccurtis wrote:Also, this is an interesting read regarding the concept of slurry breakdown: https://scienceofsharp.wordpress.com/20 ... reak-down/. It's something I've often questioned.

Kunimoto-san, in Japan flat out does not agree with Science of Sharp's conclusion in this regard. I pointed the article out to him a couple of months ago. He wrote me that "Unfortunately he won't understand how to use the hardness of the whetstone and the true whetstone yet"....