FILAMENT / FIELD NOTES

Choose a reserve without inventing certainty

Keep the margin separate from your estimate.

Sources of uncertainty

Scale readings, empty-spool tare, slicer assumptions and printing behavior affect estimates. Material condition and hardware behavior introduce issues a mass-only planner cannot diagnose.

Make the choice explicit

A reserve is material you choose not to allocate from a spool. The tool starts at zero; this does not imply zero risk. Use your own observations rather than a universal percentage. Reserve above remaining mass gives zero usable capacity.

Avoid counting twice

Include modeled supports and purge in complete-job grams. Do not automatically add them again as reserve. Additional unmodeled uncertainty is a separate choice. The planner predicts neither failure rates nor successful completion.

Learn from runs

Record input assumptions, sliced estimates and observed results for future planning. Prusa’s calculator documentation describes inputs, not a universal reserve. Return to planner.