Without a known zero reference, grinder numbers become hard to compare. Calibration makes your notes reusable.
Find your true touch point safely
With grinder empty and running, slowly tighten until burr contact is just audible, then back off slightly.
Use manufacturer guidance first. Some grinders define zero differently.
Record espresso working range
After zeroing, note where your grinder typically lands for espresso with common roast levels.
These ranges speed up first-shot setup for new bags.
Re-check after burr changes
Burr swaps, deep cleaning, and alignment changes can shift reference points.
Update your calibration notes whenever hardware configuration changes.