What this tool calculates
Turn caliper or sensor readings into a reproducible QC summary instead of judging a spool from one point.
Formula and method
When to use it
Measure along a spool at consistent intervals. For manual checks, rotate the filament roughly 90° at each position and enter the paired cross-axis readings.
Worked example
The default eight paired samples average about 1.751 mm equivalent diameter, all remain within 1.70–1.80 mm, and maximum ovality is about 1.14%.
Assumptions and limitations
Readings are finite positive millimetre values from a calibrated instrument, and paired lists refer to the same positions. A small sample cannot certify an entire spool. Measurement force, temperature, sensor calibration, sampling interval, and local defects remain important.
Common mistake
Do not average two axes first and discard ovality; an acceptable mean can hide a strand that is too wide in one direction.