This subject has been discussed in different forums, and it seems like the threads end like this every time. Putting out the same message over and over again, expecting a different outcome is probably not getting to where it should/can.
These are pictures from a different German razor forum, which i am probably not allowed to make reference to.
This is the workbench at Wacker, in Solingen. It seems like they like to finish on a flat Naniwa super stone, but the long once seems to be shaped differently. I do not think they are dished. The brown one is said to be the Naniwa Gouken Fuji 8k. I assume the yellow one is either a Naniwa Super Stone 8k.
Ralf Aust also finishes his razors on a flat Naniwa super stone (at least in the video i have seen). There is also a video from Wacker where he hones/finishes on a super stone that clearly is flat.
Here is some pictures from Ralf Aust work shop.
His spinning disk where he grinds in the bevel is definitely not flat. Even if it was flat to start out with, it will eventually be worn in to this shape if it is made of some sort of ceramics.
What makes sense from a fabrication standpoint might not always apply to the end user.
Dovo seems to do it a little different. We should not judge the method Dovo uses only by the end result. To be able to mass produce something they might have to find a balance between efficiency and the end result. Maybe it would be beneficial for them to deliver a better edge. I am not sure the customer would pay for that.
For new people coming into this, one lesson might be that you probably do not need more then a few stones to get good results.
By having a convex lower grit stone, or even just a mid range 3-5k stone (the bevel should be good from the factory) a wheel shaped stone can make the work that the higher grit stones have to do easier.
As the old grinder told Jarrod, the opposite of tape. So what is the opposite of tape? You are able to create a micro bevel without using tape.
If you have a edge that is prone to chip, this might be something to look into.
Here is an example:
The bevel of this razor was shaped using a wheel shaped 3k with a natural nagura/slurry stone stone. Technically the stone is not completely convex. It has close to the same radius in both axis, maybe a little less on the short axis.
This was not even a good edge, but this is just to make a point about the micro bevel, or about being able to focus your effort on a smaller part of the bevel. It was finished on a light slurry on a JNAT. From this picture you can see that the finisher worked on the lower part of the bevel, making that stone more efficient. It is the same thing that happens with the spinning disc. After the spinning disk they need to spend less time finishing the edge. I might add that after i test shaved this i did a few more laps on a little heavier slurry. That seemed to bring it back to a standard flat bevel.
If i had gone from the 3k i could probably have picked up a high grit fast finisher, and only needed two stones.
I have many different stones, so the time saving is really not something i prioritise. Someone else might though, for different reasons.
On the German forum the guys who has visited the factory lately said they only saw flat stones at the factory.
So, is the convex used more for the out off shape blades, or does every razor go through the same process?
It is also a little funny that some of the die hard perfectly flat stone fans say they like to end the lapping of their stone by using figure 8 motions and some circles to get the corners and sides, effectively creating a curved hone
The German forum also have some post where they show how they convex their stones.
The discussion is also really friendly
Here is part of the translated German discussion. He is talking about the thinning an backbevelling (which i have tried).
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The operator of TheSuperiorShave is the advocate of the convex stones.
And this is about convexity, especially in the longitudinal axis, so the razor must first go up a hill with each move and then down this hill again.
This convexity ensures concave provil of the facet and provides an extra thin facet angle.
However, its stones are also convex in the transverse axis, which increases the efficiency of sharpening, reduces the risk of catching the stone edge and allows sharpening of the warped blades.
His offered tool is also aimed at straightening stones in avoiding axes convex.
I have worked a lot with the convexity in the transverse axis so far and am very satisfied with the
effect.
As for thinning the cutting edge (i.e. creating a flatter facet angle), I have had a shady
experience:
- If the blade manages to hold such a thin cutting edge, the knife provides a very special shave@(@Isaentae once got a knife sharpened by me and can certainly report on the impressions)
- But the risk is very high that the cutting edge simply collapses during shaving, I have supplied enough vivid material in another strand
My method of thinning out the edge was not in the longest convexity of the stone. Meanwhile, on a flat-trained stone, I applied back-guiding trains with an increased pressure on the cutting blade. This also leads to a concave polished facet and thus to a flatter facet angle. However, this method carries a high risk of building a beard and therefore requires very close control of progress (you have to stop the back-leading flare-up just before you reach the absolute tip of the cutting edge - at the matoscopic level, of
course).
I don't use this method with every razor, it is more reserved for the phase "I want to experiment with this knife extra".
