25mm Spiral Binding Coils

No. Published capacity figures are generally based on standard 20 lb paper, so covers, cardstock dividers, laminated inserts, and coated sheets use more space than ordinary paper. Measure the assembled stack rather than adding the sheet count and assuming it will fit. The thickness should be taken at the punched edge because that is where the coil must support the entire document. A coil that is too tight can pull against the holes and make turning difficult, while an unnecessarily large coil may let the contents shift. When the document sits close to the practical limit, moving to the next suitable diameter usually gives a cleaner result. Use the thickest version of the document as the production sample if different editions contain varying numbers of inserts.

The punch pattern must match the coil pitch exactly. These 25mm coils use a 4:1 pattern, meaning four holes are punched per inch along the binding edge. A 4:1 coil will not thread correctly through holes made for 3:1, 3.2:1, or 5:1 supplies, even when the diameter looks suitable. The related 4:1 spiral coil binding supplies use the same pitch for compatible workflows. Confirm the pitch from the machine label, manual, or a test punch before ordering. Diameter determines document thickness, but pitch determines whether the coil can enter the holes at all. Never stretch or force a mismatched coil, since doing so can damage the punched edge and produce an unreliable binding.

No. Diameter and length solve different requirements. The 25mm diameter is chosen from the document thickness, while coil length follows the length of the punched binding edge. A 12 inch coil is commonly used for an 11 inch edge because the small excess can be trimmed before crimping. A shorter binding edge may require the coil to be cut down, while legal or oversized work needs a longer supply that reaches every hole. Place the coil beside a punched sample and allow a modest amount beyond both end holes for secure finishing. Too little length can leave holes unsupported, and excessive overhang creates waste and untidy ends. Confirm orientation before punching because binding along a different edge changes the required coil length.

After insertion, trim and crimp both ends of the coil. A proper crimp flattens the final loop and bends it toward the document, creating a stop that prevents the coil from rotating back through the holes. The available coil crimpers support hand finishing as well as higher volume production. Leave roughly half to one and a half loops beyond the final hole before cutting so there is enough material to form a secure end. A very short crimp may slip through the hole, while a long unfinished end can snag during handling. Gently rotate the coil in both directions after finishing. Both ends should resist backing out without interfering with smooth sheet movement.