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Hair Today Gone Tomorrow: Four Men Go to Fix a Wafer Prober
- h2odragon 5y agoSome may recall a time when magazines came in the mail with an address label that was glued on. Usually printed with a dot matrix printer. they usually had semicircles notches of feed hole in the middle, top and bottom. The machines that applied these ate big stacks of tractor feed stock, with a hot melt glue already on one side, cut them into individual labels, heated and applied them to whatever you were running. It did this operation with a spinning heated drum and vacuum routed through holes in it. I can't find links to the thing unfortunately, it was an impressive hack. Anyway, we had a clapped out one of those we nursed along for a decade in our publishing operation. At the time we were running about 10k small newspaper size things every 2 weeks or so, which would be a full day for several people running the papers through the label machine and getting them to the post office. One day the "pre-run" shows a problem: it's dropping every 6th label. The diagnosis was hard cuz it shows up as "one in 6 is something between off center to under the next one". We looked at the timing chains (always a fun source of errors). We looked at the label stock. We checked the paper we were applying to. We made sure none of the rollers had flat spots and re-tensioned all the springs in the paper path. Still the same symptom. Much more digging ensues and finally we discover a (now thoroughly cooked) spider in one of the vacuum channels in the spinning head thing. Thanks to the healing power of aerosol brake cleaner, we got the problem solved, at about 6am before mail day.