
Spools are used for the safe transportation of endless material. The material is wound onto the spool layer by layer so that it is difficult for individual windings to slip. Spools have a minimal (inner) and a maximal (outer) diameter. This has two important consequences: a difference in speed and a difference in curvatures.
See Also
Adapted from “"We do it straight" — Wire Straightening”, p. 147 (ISBN 3-00-005897-4).