Whenever I watch the countless moving parts on saddle stitching and perfect binding lines, I’m amazed that all those folded sheets of text and cover make it to the end without marks, scratches and scuffs. Well, most of the time they do.
Upon closer inspection there is nearly always a bindery operator’s ingenuity contributing to the desired outcome. These big, sophisticated binding lines have hundreds of moving parts, any of which can decide to give an operator grief at any given time. The fix is typically not in any machine instruction manual so this is where the calm cleverness of a 
good bindery equipment operator is invaluable.
Todd Summers of Nittany Valley Offset submitted this technique which he uses on the feed pockets of his saddle stitcher’s inserter. The problem arises when feeding folded cover stock signatures. As the suction bar rotates to pull down another signature, the movement of the bar scuffs the back side of the signature. [photo at right] (I’ve also seen this happen on matte and dull coated text signatures.)
The fix is simple and fast. Cut a piece of corrugated 
cardboard (not chipboard) to cover the suction bar but not the rubber suckers. Tape it to the feed pocket as shown using regular packing tape. [photo left] If the suckers fail to pull the cover down into the drum, re-position the card board as needed until the pocket feeds consistently.
According to Summers this technique allows him to fill the pocket as high as he likes without any scuffing.
As always, feel free to share your experiences, comments and suggestions below.
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