How to plan a batch with partial filament spools

Start with net mass, not the label

A spool that originally held 1 kg does not tell you how much remains today. Weigh the complete assembly and subtract the empty assembly measured with the same adapters and spool sides. If you do not know the tare, use an identical empty spool or record the uncertainty. Do not quietly treat a guessed tare as a measured value.

Turn the sliced job into a repeatable unit

Slice one complete job with its actual supports, brim and material changes. Identify which waste the slicer total already includes. Add only missing consumption to the planner. Choose a reserve to account for measurement uncertainty and the amount that cannot reliably feed into the printer.

Allocate whole jobs to each spool

For example, three remainders of 250 g, 130 g and 60 g support six 60 g jobs when each spool keeps a 10 g reserve. The third spool cannot finish a job by itself. Grouping all three remainders would hide that constraint. The calculator makes the per-spool allocation visible and exports a small CSV worksheet.

Reconcile the plan after a print

Weigh the spool again after the first successful job. Compare the real consumption with the estimate before running a long batch. If the difference is material, update the job weight. Keep failed starts and test purges in the record. A plan is most useful when it changes with the measurements.

Before you use the result

Check the measurement units, use the actual materials or equipment in your project, and test a small example. The linked calculator shows its assumptions and provides a worksheet you can keep with your project notes.

These examples were prepared for this site. They are not a report of a laboratory test or a product certification.