Hardcover book cases Are you sure they fit? - II

01 Oct 2012

we discussed in an past article, how to calculate the board sizes and width of inlay strip and cover dimensions for square back books. Now let us look at, how we can calculate the cover dimensions for hardcover books that are rounded or rounded and backed.

Rounded and Backed book blocks are more difficult to calculate. The bindings always required making sample books—a labour intensive and expensive task. There is a mathematical solution to figure out the exact cover dimensions, even if the paper is not yet available. All we need from the publisher’s production managers are the trim-size, the type of paper used, the number of pages (and the PPI), and the style of hardcover binding. We are almost ready to calculate. But now you ask, how in the world can you determine the distance over the rounded and backed spine? After all, the width of the flexible inlay is a most important item to achieve a quality hardcover binding. Well, there is a trick to it. You must establish a chart. In my case, during a slow period, I bound 20+ Smyth-sewn book blocks. They all had the same trim size. The only variations were the bulk. I started with a ¼ inch thick book, the next having a 3/8 inch bulk – all the way up to 3 inches. Then I rounded and backed the book blocks the way they should look like in production. That required some craftsmanship. When I had all book blocks ready, with a paper strip over the spine, I took careful measurements. That established the exact distance from the heights of the backed ridges on each side and the rounded spine. That data was translated into increments of one thousandths of an inch. For example, a book block with a bulk of 13/16 inch measured when rounded only .95 inches, after rounding and backing it showed 1.18.

That 1.18 equals roughly 1 3/16 inches for the width of the inlay. With this chart, it was possible to establish any cover dimension in a minute or two. Bear in mind, this was all done long before we had computers available. These days, once programmed, a cover size function is a matter of seconds. Best of all, if a Q.C. manager evaluates the finished bindings, some minor adjustments can always easily be made.

Now let us go back to our examples and calculate the requirement for a hardcover binding with a trim size of 6" x 9" and a bulk of 13/16 inch.

Board size

5 7/8"

X

9 1/4"

Joint area
Inlay
Joint area

1/4"
plus 1 3/16"

plus 1/4"

 

 

+ Board size

5 7/8"

 

 

= Cover size

13 7/16"

X

 9 1/4"

+ Turn-ins
(all four sides)

  5/8"

plus 5/8"

 

5/8"

plus 5/8"

Cover stock dimensions

14 11/16"

x

10 ½"

For heavy covering materials, allow a little more for the turn-ins.

The measurements used above are for Smyth-sewn book blocks. Adhesive bound books do not and should not be backed as much. Therefore deduct 1/16" of the width of the inlay, shorten the boards and increase the joints to 5/16". Again, all such data is most valuable to get a useful cover size program started. With minor adjustments made in time, it is perhaps one of a most useful tool for anyone who must produce quality hardcover bindings.

No matter what binding style you may produce, such a program is now even more important than ever. These days, most of the covering materials used are printed. The placements of the images are most often very critical. That is just one more reason why book covers must be calculated with an utmost precision, no matter if you are an edition, on-demand or photo book binding facility.



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