TRUST & TRANSPARENCY
Method & limitations
Operated by Lorenzo Luna in Argentina. Contact: lorenzo.m.luna.g@gmail.com.
Spool Margin Beta is a free experimental planning utility for adults. It does not operate printers and is not affiliated with printer or filament manufacturers. Development was assisted by AI. The working name has not received professional trademark clearance.
What is calculated
Available lower = max(0, loaded lower − tare upper); available upper = loaded upper − tare lower. Required lower/upper = job lower/upper + extra reserve. Worst-case margin = available lower − required upper; best-case margin = available upper − required lower.
Fits the entered ranges: worst-case margin is zero or positive. Short across the entered ranges: best-case margin is negative. Otherwise: uncertain. Equality only at the optimistic edge is uncertain. Zero worst-case margin leaves no extra material beyond the allowance you entered.
Bounds and physical limits
All inputs are grams. Bounds must cover uncertainty you can justify, including scale accuracy, matching-spool differences, and job accounting. Scale resolution alone is not accuracy. Ranges are not probabilities or statistical confidence intervals. Correlation between measurements may make independent extremes conservative; unknown systematic errors can still invalidate the result.
Physically feasible combinations require loaded mass to be at least tare. If every loaded mass is below every tare mass, input is rejected. If the ranges overlap, available lower is limited to zero and a warning appears. This does not validate the tare.
Each input is nonnegative, at most 100,000 g, with no more than two decimal places. Integer hundredths of a gram preserve decimal boundary comparisons; displayed precision is not measurement accuracy. A positive upper job bound is required. One spool must be compared with its own job consumption, not a combined multi-material total.
What remains unknown
Unusable filament, feed faults, tangles, moisture, slicer omissions, and material quality are not predicted. Include defensible allowances yourself; do not count supports or purge twice. No result guarantees that a print will finish. Follow manufacturer and slicer instructions independently.
Evidence and review
Teaching examples are original and synthetic. Automated tests establish arithmetic and software behavior, not physical print success.
Independent maker review of measurement instructions and three measured cases is pending. This free experimental beta is made available before that review. No independent physical scale, filament or printing validation is claimed.
Editorial and commercial policy
No advertising, affiliate links, testimonials, customer figures or revenue claims are present. Future monetization requires separate owner approval and clear disclosures, and must not change arithmetic or hide uncertainty. Corrections are checked against the stated method and recorded in a dated local change log.
Policy version: beta-1.1. Policy review date: 2026-10-12.