Punching for spiral binding of any kind is a tricky matter and for plastic coil it is even trickier. Punching for double loop wire has always been a snap: Merely open your die. Place your sheet against the pins and pull the pins nearest the edges of the sheet. This way there is no chance of punching a partial hole. You have the luxury of centering your sheet and producing a generous, attractive margin (the distance between the first or last hole and the head or foot of the book). Punching for spiral is not always so easy.

If you have a plastic coil machine that can manipulate the spiral prior to insertion, consider yourself lucky-Most cannot! Therefore whatever pitch the spiral may be, that is what you are stuck with. Let's use the industry standard of the 4:1 pitch.

In days gone by metal spiral binding used a 4:1 (or in Europe a 6mm center to center) pitch. But back in those halcyon days, the holes were small, 9/64" (3.5mm). They only needed to accommodate a very thin gauge of wire. Plastic coil gauges are much thicker, some as thick as 1/8" (3mm) and 9/64" holes just won't do. Standard plastic coil gauges range from .063" to .085" (1.5-2mm).

Some had turned to oval holes. Oval holes were, for many years, the accepted way to battle thicker books with wire spiral and, even for a time, plastic coil. The old standard was a double "D" die. Why is it called double "D"? Imagine two D's mirrored against each other and turned counter clockwise 90 degrees. It is actually a round hole with its sides sliced off. A double "D" die used to be 9/64" (3.5mm) wide and 11/64" (4.365mm) tall. 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.

When automatic plastic coil machines came into the fore these holes proved too tight. While the holes are tall enough, automatic machines which drive the coil horizontally, need more "wiggle" room from side to side and 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. This wider hole led to a problem:

Forty-four round 11/64 inch holes will not fit attractively on an 11 inch (or A4) sheet. It will leave you with a razor thin margin wholly unacceptable to the customer. What many manufacturers did was devise an entirely new die pattern: The .2475" pitch die. This means one hole for each .2475 inches. But the problem was that the hole was still too small to accommodate many automated coil binders. If the hole was made any bigger it would punch a partial hole off the edge of the sheet. The solution was to make the die an oval die, but not your grandfather's oval die, a new, oversized oval die: 11/64" (4.365mm) wide and 7/32" (5.5mm) high. This allowed for a bigger hole without causing punching too close to the edge of the sheet. It also forced customers to purchase brand new dies for their punching machines with this pitch. If you ask your coil equipment dealer why you would need an oval die and he says it is because the coil spins in more easily, you should question as to why coil would spin in more easily than a round hole of equal overall size. The answer is that it wouldn't. The reason for oval holes is because you shouldn't punch too close to the edge of your sheet.

Some coil binders can only use this new .2475" pitch with all coils. Some can use a 3:1 pitch but that will look unattractive on thin books. Some coil binders can use any pitch. It is recommended that in binding books thicker than 22mm in diameter you move to a bigger pitch. Popular sizes are: 3:1, .312", and 2.5:1. What are the reasons?

Thick books bind more easily with less coil running through them and also need a thicker gauge coil to handle the weight of a heavier book. A 30mm book looks better with a 3:1 pitch than a 4:1 pitch. If you are binding thick books you would want to use a bigger round or oval hole. If you use a bigger hole, they will be too close together on a 4:1 pitch. However, bigger holes will allow bigger pitch diameter and heavier gauge coil to spin through more freely. Coil costs for 3:1 coil is 25% less than on 4:1 coil. Need I say more?

To save money, time, and aggravation find out the following before purchasing a coil binder:

*Will I need to purchase new dies to use this coil binder?

* What size hole will I need to punch?

* Will the machine bind books with round or oval dies?

* What pitch can I use when punching for this binder?

* Can I change pitch sizes for thicker books?

* Can I pull pins prior to punching and center the sheet like I do for double loop wire?

Ask these questions. You will be glad that you did.

SPIEL ASSOCIATES invites you to visit their web site, www.spielassociates.com for more information on this subject or their NYC showroom. Call them at 718-392-7900 for a brochure or video on their machines.