Troubleshooting on a saddle stitching machine can be a frustrating task, especially with a multi-pocket signature feeder, a stitching unit, a caliper system, cover feeders, and a 3 or 4-knife trimmer component all running inline. Spice it up with various signature sizes, small cards, signatures with no lip, poorly folded signatures, 2-up work plus throw in a machine with some wear and tear, and you have the recipe for a bindery equipment operator’s nightmare should a problem arise.
A recurring theme in the feedback is that troubleshooting complex bindery machines such as stitchers is, as one reader put it, like ‘peeling the layers of an onion.’ A question asked by an operator about a problem is usually met with several questions in return. Experienced, successful operators are very systematic in their approach, and will go through a mental checklist of such questions to find the problem. Watch a good operator quickly solve a problem then ask him how he figured it out, and it could take a long time to get the full answer! In all likelihood you’ll get a short answer that leaves out the details.
Keep in mind that there are many machine and model-specific procedures that address most problems. Of course some problems are obvious. For instance, signatures dropping on the floor alert you that the pocket isn’t set correctly. An experienced operator always includes a quick scan of basic make-ready items—pocket timing, chain position, air, etc.
One simple but powerful technique to help ferret out both the obvious and the more subtle, hidden problems is to make use of the reject tray.
During make-ready, run a few dozen stitched books into the reject tray before trimming. Check to be sure registration of signatures and stitching is perfect before you start running (and before you set the trimmer.)
If a problem pops up while running, check the reject tray books if the problem isn't obvious. If you're stumped, repeat the above make-ready procedure.
You can find many clues about a problem here. Patterns emerge. For example, if one signature repeatedly mis-registers or misses, it might indicate a problem with the way that pocket was set. If every X number of books is out of register, there could be a problem with the chain. If mis-registered books appear in random fashion, it might be a problem with the chain rail or with the caliper. You may not get the answer to your problem right away, but looking at a sampling of books will save you time by pointing you in the right direction.
This is one general tactic that can be used on almost any saddle stitcher to peel back the layers and narrow down the source of the problem.