I think that Sharpco poses an excellent question. It can be taken as “Are CBN wheels better for the Tormek?” and as “If CBN wheels are better, why hasn’t Tormek offered two CBNs as an alternative to the SG-250?”
On the first question, I and most of the dry-grinders I know (mostly turners) have gone over to CBN on dry grinders for tool shaping and sharpening purposes. In dry grinding they have three important advantages (over stones): negligible heat, excellent balance and alignment, and constant diameter.
The first two of those are not an issue on the Tormek, so the main advantage on a Tormek would be the constant diameter. This is not a big deal if you don’t mind adjusting as the stones shrink.
With that said, I recently got two CBN wheels for my T8 (from Woodturners Wonders; they have several Tormek-compatible 10” CBN wheels with 12mm arbors in various grits). That is because, for one of my recent uses of the Tormek (repeatable grinds on scandi carving knives), the constant diameter is very important to me. Also, though they can be used wet with an anti-rust agent, they are designed to be used dry, which is easier on my lovingly made custom knife handles.
While, as Herman notes, Tormek would not see having a constant grit as an advantage (relative to the variable grit SG-250 and SB-250), I don’t find swapping wheels to take any longer than re-grading the stones, so that factor is a wash for me.
And an advantage on the Tormek (that isn’t much different from stones in dry grinding) is speed: I have found that a coarse CBN is a lot faster than the SB-250 graded coarse. Probably similar to the Tormek diamond stones.
Now on the second question, why Tormek doesn’t introduce CBN wheels, I agree that Tormek should (and probably will) come out with CBN wheels, but given the fairly narrow application, I can see that it would not be a priority for them. They have just introduced the diamond wheels, and CBN might complicate their marketing.
Which is to say, I sense that the main reason we don’t have CBN wheels from Tormek is Tormek’s general prioritization, for marketing reasons, of simplicity over optionality. This might be good marketing. They might be concerned that if they give people choices, people will perceive the Tormek system as too complicated. I think that they are slowly getting over that, as shown by the new wheels and other innovations in the past few years, but it does seem to be like a big slow-moving ship. In the meantime, the option is there in the aftermarket.
