Last month, I posted a query about our SP-15 at UA Fort Smith, in which the trip eccentric release mechanism in the cylinder was crashing into the trip release button on the operator’s upon return to home. (see the original post https://vandercookpress.info/vanderblog/2011/02/sp-15-carriage-problem/#comments). This has begun happening again, despite oiling the press every time we print with it. This only seems to happen when we are in print, and it is still intermittent. As noted before, this press was neglected for years and has a LOT of grime built up. Paul cleaned the mechanism somewhat when he tuned up the press and we have kept it well oiled, too.
Have any other SP-15 users experienced this? Is it something that these presses all suffer from due to the design? I’m thinking of purchasing another SP-15 for our shop, and don’t want to have similar problems. I have used other SP-15’s and don’t recall this issue, so perhaps it is not a flaw that they all share.
Maybe it’s a combination of not so hot design made worse by grime. If it’s due to the grime, does that mean we will have to disassemble to clean? I seem to recall that is a nightmare job…
More diagnostics run today. Eric mentioned making a mark on the side of the carriage and on the cover plate of the trip mechanism, and I found those marks already on the press. He was right: when the trip “drifted” on the return trip to home, the marks did not line up and I could anticipate the crash. I found that there seems to be an excessive amount of play when the cylinder is in trip, so that one can actually cause the trip mechanism to move just by wiggling the handle at a certain spot, which sometimes happens when we roll out in trip to ink the form. Someone had mentioned that short rolling might be the issue, and while this is not always caused by short rolling, the short roll can lead to the bogus handle position. I hope that makes sense. I may try to make a video. Anyway, I’m going to train the students from now on to roll all the way to the end of the bed; that seems to prevent the arm movement that pushes the trip out of alignment on the return trip.
I’ve seen Mylar shims, too. I doubt that the cover plates were ever messed with after it left Chicago.
Another thing that interferes with the movement of the eccentric is over-tightening of the cover plates. I have seen them with copper shims to control the spacing, or just using setscrews for clearance. But if you tighten the cover plates until they touch the side plates of the carriage, the eccentrics will not budge. There must be clearance.
When examining the press, it can be helpful to put a mark on the cover plate, then marks on the side of the carriage denoting trip and print positions. Then you might notice if things are wrong before you run into an obstruction.
I can only imagine your frustration. I did as much as I could in the time we had and thought it was running fine when I left.
I think that the side plates will need to be removed to do a deep clean and lubrication of the cylinder eccentrics. This amounts to a complete tear down of the carriage. Everything that connects the two sides together has to be removed: the oscillator and rider, tie rods, etc. The lower carriage bearings can stay connected, but the top bearings have to be removed. I can talk you through it or I can come back if you wish.