Three-knife trimmer problems: causes and fixes
8 Three-knife trimmer problems in offset printing and finishing: symptoms, probable causes, step-by-step fixes and prevention.
Three-knife trimmer · TPG-247
Variable sizes between books in one run
Inconsistent final format; some books shorter or narrower
Three-knife trimmer · TPG-248
Off-square cut (rhomboid book)
Head and foot not perpendicular to the spine; visibly crooked margins
Three-knife trimmer · TPG-249
Draw: cover or first pages pulled
Cover or top sheets shorter or with an inward-curved edge
Three-knife trimmer · TPG-250
Rough, torn or flaky trim edges
Edges not smooth; torn paper; flaking on laminated covers
Three-knife trimmer · TPG-251
Clamp marks on the cover
Sunken or shiny rectangular imprint on book covers
Three-knife trimmer · TPG-252
Concave or convex front trim (block draw)
Front cut not straight: bowing in or out at the book's middle
Three-knife trimmer · TPG-254
Front and side cuts out of sync
Double mark at the corners; bitten or stepped corners
Three-knife trimmer · TPG-253
Trimmings jamming or lingering in the cut area
Trim strips piling up, soiling the next cut or jamming the machine