Stone Grader Discussion (SP-650)

[Swemek]

I'm a tormek newbie and would say that my SP-650 is very young. I have noticed that it takes longer to achieve low grit than it did when it was new. The fine side still seem to be as effective as it was when it was new. I can clearly see the coarse side of the SG is getting more shiny. Is there a easy way to get the rough side back?

I have a 8" 150 grit diamond plate that I got from a respectable knife shop in Stockholm. This shop sells fancy kitchen knives and Shapton stones and the 150 grit diamond stones is for stone flattening. The thing is that it is way more effective than the coarse side of SP-650. I apply very light pressure  when grading and the result is really good. It seem to hold up well for this particular use, way better than my DMT DiaSharp stone, that got big shiny spot when it touched the SG-250. Im very skeptical towards DMT after this.

I suspect that the light pressure used with my diamond stone doesn't get me all the way to 360 grit, but very swift to maybe 5-600 grit. This might sound strange, but even if the result from the diamond stone gives somewhat higher grit, it feel so much more aggressive, in a good way, compared to what i get with a new SP-650.

SP-650 might be the best allround grader in the long run, but when it comes to sharpen and re profiling knives with 58-60 HRC, the 150 grit diamond stone has been great.

 I'd love to hear your thoughts on this.

Thanks!

[cbwx34]

I'm a tormek newbie and would say that my SP-650 is very young. I have noticed that it takes longer to achieve low grit than it did when it was new. The fine side still seem to be as effective as it was when it was new. I can clearly see the coarse side of the SG is getting more shiny. Is there a easy way to get the rough side back?

I have a 8" 150 grit diamond plate that I got from a respectable knife shop in Stockholm. This shop sells fancy kitchen knives and Shapton stones and the 150 grit diamond stones is for stone flattening. The thing is that it is way more effective than the coarse side of SP-650. I apply very light pressure  when grading and the result is really good. It seem to hold up well for this particular use, way better than my DMT DiaSharp stone, that got big shiny spot when it touched the SG-250. Im very skeptical towards DMT after this.

I suspect that the light pressure used with my diamond stone doesn't get me all the way to 360 grit, but very swift to maybe 5-600 grit. This might sound strange, but even if the result from the diamond stone gives somewhat higher grit, it feel so much more aggressive, in a good way, compared to what i get with a new SP-650.

SP-650 might be the best allround grader in the long run, but when it comes to sharpen and re profiling knives with 58-60 HRC, the 150 grit diamond stone has been great.

 I'd love to hear your thoughts on this.

Thanks!

I think you are correct.

A couple of things you can try with your SP-650... I've roughed mine up using a nail or an old screwdriver, just scraping the surface to freshen it.  You can also use the edge of the stone for the last few seconds of grading... just rotate it a little until the edge is making contact with the wheel.

But several on here have used diamond stones to grade the stone with good results.

[3D Anvil]

I guess you would recondition the conditioner as you would any whet stone, so a diamond plate, as CB suggested, or you could use sic powder or playground sand on a glass or granite plate.

[Swemek]

I'm a tormek newbie and would say that my SP-650 is very young. I have noticed that it takes longer to achieve low grit than it did when it was new. The fine side still seem to be as effective as it was when it was new. I can clearly see the ..snip ...............snip..
SP-650 might be the best allround grader in the long run, but when it comes to sharpen and re profiling knives with 58-60 HRC, the 150 grit diamond stone has been great.

 I'd love to hear your thoughts on this.

Thanks!

I think you are correct.

A couple of things you can try with your SP-650... I've roughed mine up using a nail or an old screwdriver, just scraping the surface to freshen it.  You can also use the edge of the stone for the last few seconds of grading... just rotate it a little until the edge is making contact with the wheel.

But several on here have used diamond stones to grade the stone with good results.

Thanks for the reply! Yes that's exactly what I did, using the edge to make it a little more aggressive again!

I guess you would recondition the conditioner as you would any whet stone, so a diamond plate, as CB suggested, or you could use sic powder or playground sand on a glass or granite plate.

Great tip, I'll try that, thanks!

[cbwx34]

...

But several on here have used diamond stones to grade the stone wheel with good results.

I reread this... I meant using the diamond stone on the wheel not the stone grader.

[Ken S]

In my opinion, Tormek probably introduced the stone grader around the time they were switching from the natural sandstone grinding wheels to the faster cutting aluminum oxide SuperGrind man made wheels. These wheels are coarser and cut faster. However, I suspect some users missed the smoother finish of the finer grit old wheels. The stone grader provided a clever way to make SG wheels do double duty. It still does that function well.

Much later, the SB blackstone and 4000 grit SJ stone were introduced. The stone  grader has always has limited use with the SJ. Supposedly, the SB can be graded like the SG. I have never actually seen this done in any of the twenty four online classes.I suspect many of us, including me, quietly use the SB with the TT-50 truing tool to obtain a coarse surface and diamond plates to occasionally obtain a finer finish.

Ken