Why Don’t the Spines On My Print On Demand (POD) Books Line Up? — juliekaren.com

So why do the spines not match up in the print, if they match up in the file? Basically, the trimming and binding at Amazon KDP (and any print on demand printer) is not as accurate and not as high quality as it would be with a traditional book printer. As each book is printed “on demand” (one by one when each book is ordered), the variance comes in somewhere in the printing, trimming and gluing process. A tiny shift anywhere in this process can mean that a spine is not quite centered vertically or horizontally. I assume that the operator (if there is one—the whole POD process might be done digitally) doesn’t have the time to pay attention to finer production details like this.

Unfortunately, this varying quality happens a lot with print on demand printing. If your book really needs to match perfectly, you probably need to print it traditionally and not print on demand! But print on demand has so many other pros, that this small con might not discourage you from using it anyway! Just make sure you know the strengths and weaknesses of print on demand before your commit to one or the other route for book printing and production!