Spiral Binding: Getting the Coil Diameter Right

Coil diameter is chosen from the thickness of the finished block, and both errors are annoying.

Too small

The document will not close, pages bunch at the spine and the coil is under constant tension. It will eventually distort.

Too large

Pages slide along the coil, the document feels loose and it will not sit squarely on a desk.

Measure the block

Measure the actual stack including covers and pick the size that leaves a little movement without slop. Covers matter more than people expect — a heavy board cover changes the size needed.

Crimping

Trim and crimp both ends properly. An uncrimped coil unwinds itself gradually in a bag, and by then the pages are already in the wrong order.