The Right Grooves

Here's an interesting observation that I thought I'd share and see if anyone has seen the same and/or has any feedback. I've done a lot of work in the last couple of months on measuring and controlling my particle size. At about the same time I bought another Spectra 11 and fired it up. I noticed immediately that the new melanguer was MUCH slower in reducing the particle size (I just confirmed that the original set will take 1.5 kg down to less than 20 microns in 12 hours, while the other two sets take over 40 hours at the same approximate spring pressure). After ruling out the springs (by swapping them) I noticed that the wheels from my first Spectra 11 were radically different than those from the new one. I also have an extra set of wheels that I bought a couple of years ago as spares -- and guess what -- they're different than either of the other sets!

The original set has one wheel with two large grooves and the other three large grooves. The 'spare' set also has this arrangement. The new set has one wheel with one large groove and the other with two large grooves. At first glance the original set and the spare appear the same, but on closer inspection there is an important difference. The original set has many tiny grooves cut in the granite between the large grooves giving the wheels very small ridges across its full width. Neither the spares nor the set I just got with the new melangeur have these smaller grooves - they are flat and smooth between the larger grooves.

It makes sense -- ridges = higher pressure, shear, etc. Now I want to either get another set of wheels with the smaller grooves (why did Santha change them???) or have the wheels I have cut -- know any good stone cutters?

Has anyone else dealt with this?

Thanks,
David