Oh groan .. another bloody sharpening thread. Well, perhaps this has a more practical goal.
Fred asked a question (in another thread - I did not wish to sidetrack that) regarding the grit of the Shapton diamond dressing plate (which is 275 as I recall. I have one). What this reminded me of was a question I have been meaning to ask for some time regarding the grit of a dressing plate.
First off, we use stones (water-, iron- and diamond) of a range of grits to hone plane and chisel blades, usually starting around 1000 and ending north of 8000. Sometimes up to 50K. In waterstones I have Shapton 1000, Sigma 6000 and 13000. I am not sure what the Spyderco ceremanic stones are rated at. It does not matter.
The issue is 'what does it matter what grit we use to dress a stone?'. Does it make a difference to the results from (say) a polishing stone (8000 or 13000 grit) if the dressing stone is 275 grit or 600 grit? In other words, can the structure of a sharpening stone be altered by the grit of a dressing stone?
Is this the same as using a stone which has grooves - would it make any difference whether the stone is smooth or pockmarked? Logic says to me that grit is grit, and that surface conditions do not matter.
However, I am reminded that the Tormek has a wheel that is 220 grit. It can be "regraded" to 1000 by using a dressing stone. No doubt this works so by a crushing action on the surface of the wheel, which reduces the 220 to 1000 particle size. Yes, no? But is this the same thing as a diamond dressing stone being run across the surface. Surely it is not crushing the grit. It may create larger or smaller mini "furrows" but these should not alter the grit, per se.
A second, related question ...
I read of warnings that dressing a polishing stone (e.g. Spyderco Ultra Fine, or a natural oilstone, such as a Hard Black Arkansas) will release fresher grit, and the stone will not polish as well as beforehand. To me, that is like saying the constant pressure of sharpening a blade crushes the grip, creating finer grit. However, the stone cannot remain this way since the surface becomes glazed and will not cut. What is better, a dedicated stone for a specific task that is dressed frequently for ultimate cutting action, or one that works at a higher grit than intended by nature, but do so slowly? If the latter was supported (I shudder!), then we would all have a series of dressing plates ranging from 275 through 6000+ grit just to avoid hampering the potential of the polishing stone.
Regards from Perth
Derek