Ive had my Universal III for almost a year now and have been running some large editions on it. 99.9% of the time she runs perfectly, but occasionally upon returning to the feed table the carriage will slam home with a startling amount of force. Im talking once out of a few hundred cycles and it seems to be more frequent towards the end of the edition run.
I’ve already replaced all the microswitches. Adjusting the braking knob does stop the carriage shorter but when it slips it will still slam home, even with the knob turned up all the way. I have not adjusted the clutch at all. Any thoughts on the cause? Thanks in advance.
Paul – I adjusted the limit switch cam to engage the feed table end microswitches a bit earlier in the cycle. Seems to have helped but still getting the occasional slam.
Dan – Ill definitely take a look at both the switch levers and the contacts and report back.
One other thing- have a good look at the position of the lever projecting off the microswitch. The angle can be set and I have found that I tend to accidentally set them so that they don’t engage as hard as they should. This means that they sometimes don’t tell the carriage to slow or stop. If your press is slamming the feed board end, check the two at that end. Set them so that they engage a little more aggressively when the carriage returns. Also make sure that the screws holding the complete microswitch units in place are good and tight so that the whole units aren’t moving. s
I would suggest replacing some points in the contactor relays. They are quite difficult to find these days, but if you take them out and determine which ones are most pitted, you can swap them around. I have had some luck searching for used units on eBay and using just the points. Here’s one that could yield some decent spares- http://www.ebay.com/itm/231028582000?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Another thing that might help (but not a permanent fix)- when you take out the contacts, you will likely find that they are pitted from arcing and the more they are pitted, the more they arc and degrade. If you swap some of the outer ones to different inners, the pitting will match up differently. I have found this occasionally to provide better contact and a cleaner circuit.
According to the manual, clutch adjustment (described in the manual and on the carriage cover plate)is done after adjusting the limit switch cams (the rail that contacts the limit switches (aka microswitches). Note the current position and compare it to the photo in the manual.