CoyoteOldMan What is the difference in weight of the Ditting 55mm steel burrs, vs the 55mm ceramic burrs in the Vario/Forte grinders? 😀
Nevertheless, given similar base materials (I don’t think many grinder burrs are made from aluminium & none from lead, or uranium), I agree that burr weight may not be the most significant difference.
Why do they need to produce grinds of the same size? All brew methods have a range in useable grind size. Grinders are usually adjustable, you can vary the burr gap with different burrs to reach an equivalent ‘size’ (here, by “size” I mean a normalised extraction at the same brew parameters, rather than an identical average size and/or distribution). Grinders make very varied grind distributions, but these very large measured differences are not intuitively, nor linearly related to quality. They are absolutely not constant, nor close to. They are repeatable (e.g. the same grinder grinds to a repeatable distribution, but this may not match other grinders).
‘Grind size’, as a concept, is not intuitive either, two grinds of the same average size (d50) can have very different distributions and another indicator (d10, or d16) may be a better predictor of extraction for a given method. In the old CBI research, they did specify average size, but they had also established a known/expected distribution characteristic.
I have seen blade grinders with a smaller std.dev in grind distribution than some burr grinders.
Fellow originally warned people off changing burrs, especially to SSP, then changed their stock burr and then offered SSP as an OEM option. In short, they obviously screwed up the original design.