Burr alignment — how parallel the two burrs are — matters more on flat burrs than on conicals, and it can make a good grinder perform badly.
The marker test
- Remove the top burr.
- Draw over the cutting edges with a permanent marker.
- Refit, and grind a small amount of coffee at a fine setting.
- Remove and look at what came off.
Even wear all the way round means aligned.
Marker gone on one side and intact on the other means misaligned — one side is cutting and the other is not, so half the coffee is being ground by a wider gap.
Why it matters
Misalignment widens the particle distribution: you get some coffee ground to the setting and some ground coarser. That is exactly the inconsistency you bought a burr grinder to avoid.
Fixing it
Shims — thin washers under the burr carrier — are the standard fix on flat-burr grinders, and there are active communities documenting which grinders need what.
It is fiddly and it is genuinely effective. An aligned mid-range grinder can out-perform a misaligned expensive one.
Conical burrs
Far more tolerant, because the cone self-centres in the ring. Alignment is rarely the problem on a conical grinder.
Last reviewed 8 August 2026