This review consists of :
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This review consists of : |
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Ad copy from Tools From Japan :
These special waterstones are purpose designed for shaping and sharpening High Speed Steel and also to cut faster in harder, tougher steels than any other stone available. To accomplish this they are composed of abrasive and nothing more. There is no binder as is present in most all other waterstones, which means that these stones do break down a little more quickly than hard ceramic stones. In exchange for this apparent flaw, they cut significantly faster than any other commercially available waterstone on the market. Depending on the steel being sharpened, between 30-200% faster, which alleviates the dishing concern to such an extent that in most situations, it will not be noticeable. Simply put, they do their work before they have a chance to get out of flat. Made by compressing abrasive under high pressure and heat as a type of sintering, these unique stones might rightly be called a true 'ceramic' stone, and are unlike any other stone commonly known. While they are designed for very hard, tenacious and tough steels, they also cut more simple and softer steels at a rate that is difficult to describe. If you are used to waterstones that 'cut quickly', the Select II is on an entirely new plane of fast. These stones do require some soaking, especially the lower grit stones, but perform best 'just damp' and after some slurry is generated which occurs very quickly. They are also virtually immune to clogging due to the abrasive breaking free of the stone so easily. Any possible clogging is removed as soon as it occurs. Occasionally the term 'amazing' might be used for waterstones, but is only really appropriate with these. They truly are amazing.
The images at the right are of :
They show that even though this is a very fine stone it has a very open structure which would be expected given the way these stones are promoted/made. The open structure is intentional and is how the stone can cut very hard to grind steels due to high pressure (from the open holes) and the breaking away of the abrasive keeps fresh and sharp abrasive in contact with the steel.
This stone does not respond significantly to soaking which isn't surprising as it isn't a very open structure. A five minute soak shows no bubbling at all. While the stone obviously absorbs water it can be used as a splash and go easily, however there is also no reason not to leave it permasoaked (taking necessary stops against bacteria and mold).
If used very wet the stone will tend to form what is usually described as a "creamy" mud. This forms faster as the steels are softer and easier to grind as the abrasive digs deeper into the steel and is more easily torn out. In general as the mud forms so quickly there is no need to use a slurry stone, in fact the mud forms so quickly that it doesn't tend to break down unless the steel being sharpened is very hard and difficult to grind.
As a general rule :
This is done in an attempt to minimize the wastage of the abrasive which would be very high if the stone was used very wet and the steel was something easy to grind such as 420HC.
The 50X magnification of an edge to the right shows one of the main reasons for trying this stone. This edge was formed using a 700X Bester on a large Chef's knife from Jeremy McCullen :
Now to be clear this edge was just shaped, not effort made to minimize the edge bevel but it takes as much time to do that refinement as to actually do the shaping and note the steel wasted as those points all have to be ground back to produce the higher polish preferred on a Chef's knife.
The 50X magnification shot at the right is an edge on a :
The edge formed clean, no sign of a burr even at 50X magnification. This edge was also just shaped, no effort made to sharpen/minimize the burr. Now this is slower of course than a lower grit stone, in particular it took :
However there is no burr minimization steps required with the SPS-II 3K so the time is only twice as long, and there is also less steel removed from the bevel which increases the lifetime of the knife. It also provides the maximum edge retention/durability as the heavy burr formed by the Bester 700X will stress the steel behind the edge as well.
This stone of course is designed/optimized for high speed steels and other hard to grind/cut steels. This is due to the minimal bond and design of the abrasive. This allows it to cut well even steels which have a reputation of being difficult to sharpen.
The 50X magnification image at the right is of a edge on :
ZDP-189 has a reputation as being very easy to chip in sharpening (usually when used on rods or when excessive force is applied) however the SPS-II 3k easily brings the edge to an apex which forms clean with no visible burr or fractures.
As an attempt to evaluate the stone under less than ideal techniques :
Even with this sloppy shaping only a minimal burr is formed which is very trivial to remove with standard techniques.
Flattening a stone vs using it without flattening is one of the popular debates in the industry. The argument against flattening by people such as Murray Carter is simply that it is wasteful (as you are just throwing away abrasive) and that through careful use of where you hone you can keep a stone flat enough for use. However as noted in the video in the right and described in some detail in the description, there are issues with edge angle consistency and sharpening efficiency .
The best method to keep this stone flat is to take advantage of the fact that it is likely to wear far less than the more coarse stones used and thus to just use the coarse stones to flatten it. If however it is being used more frequently then the the personal solution used is to just grind it flat using cheaper coarse benchstones as they are in common supply as they are obtained as gifts. Even a simple and inexpensive $3 hardware store hone can be used to keep this stone flat for its lifetime. A few simple rules :
It is kept flat by lapping it with such a coarse stone after every 5000 passes and this only takes 50-100 scrubbing passes with the coarse benchstone.
The 50X images on the right show (from left to right) :
The hypothesis here was that the Henckels 3k which is a much harder stone would be more suitable for the softer and easier to grind steels as it would not have same high wear and waste of abrasive as the 3k SPS-II which again is intended for HSS and similar materials. The edge finish is comparable but there is much more to using a stone than the finish it produces.
In use not only does it produce a comparable finish but it does tend to show the exact characteristics requires :
however there is an issue revealed once the sharpening is stopped and the stone is rinsed off.
As is obvious from the image at the right, the stone loads very quickly in use. This is a splash and go stone and doesn't tend to absorb water nor does water penetrate easily into the surface.
The fact that it loads quickly has two consequences :
The latter is kind of ironic as it was used in an attempt to actually combat the high wear of the SPS-II 3K on soft steels but because it loads very quickly, even 100 pps is enough to load the stone and start burnishing, it has to be lapped to keep the abrasive on the surface clean and exposed.
Now to be clear if this stone is used with a slurry stone then the loading can be minimized however it is just as fast to lap the stone and keep it flat than to use a slurry stone to scrub the surface and remove the loading. The two processes are identical, the only difference is that slurry stones are typically much finer than lapping stones.
The 50X image at the rigth shows the edge on a :
The edge it produces is very fine, easily on par with the 3k SPS-II (the medium ceramic is approximately 12.5 microns).
The Spyderco medium ceramic will tend to produce a finer surface finish than the 3k SPS-II. The medium ceramic will leave the surface in a state which is clearly starting to become a mirror polish as shown in the image in the right. However the SPS-II 3K generates a much more hazy finish.
In general it is also easier to get a knife sharp off of the Spyderco stones (when clean) than waterstones due to the fact that waterstones wear as they are being used and they form a mud which can directly abrade the edge. This is why when the final sharpening is done with waterstones they should be :
so they are flat and generate very little mud in the final sharpening use.
However it isn't a direct and only clearly superior position for ease of sharpening for the Spyderco benchstones because as get loaded with metal they start burnishing the edge (deforming it) and thus they can generate problems as they will push the edge around and often generate complaints about producing edge bias where the edge shaves on one side and now the other.
The problem with the Spyderco stone is however the exact same as their strength. As they are solid sintered ceramic and do not release abrasive (very easily) they tend to very easily load. The image on the right shows a significantly loaded stone which is after just :
If this steel isn't removed then the stone stops abrading and starts burnishing. There are many ways to remove the steel, including cleaners and abrasive scrubbing pads, the simplest is using a variety of eraser which will trap the metal and remove it from the stone. However no method short of chemically dissolving the steel will render the stone fully clean.
The question then is one of is the lapping of the waterstones and the techniques requires to put on the final edge more desired vs the frequent cleaning required of the solid sintered benchstones from Spyderco. Note to be really clear the Spyderco stones will wear and eventually have to be lapped flat but it takes a long time, most people never have to do it.
Comments can be emailed to Please Use the Forum or by posting to the following thread :
and/or the YouTube Playlist for Abrasives/Sharpening.
Most of the pictures in the above are in the PhotoBucket
album.
| Last updated : | |
| Originally written: | 09/09/2013 |