Coil Binders — Punching for Plastic Coil

This, obviously, helped with insertion of spiral wire and hand-held plastic coil books. However, oval dies are much more expensive than round hole dies since they have to be EDM'd (laser burned). They can cost up to $2,500 more than a round hole die.

These holes proved too tight when automatic plastic coil machines came into the fore. While the holes are tall enough, automatic machines, which drive the coil horizontally, need more "wiggle" room from side to side. Hence, a new standard was born: The 11⁄64˝ (4.365mm) round hole. This is now the standard round hole for plastic coil within the industry.