Hello, we have a Universal 1 press, serial # 28671 (1969) that was converted from being a power drive to manual press by Don K. Black.
Recently, we have noticed that the grippers are not releasing the paper fully at the end of the bed.
The grippers all raise up and open easily at the start of the run when we step on the gripper pedal, but do not release the paper ‘easily’ at the end of the run.
(Images of the gripper pedal in action)
I have taken apart the gripper assembly and lubricated it with graphite. I have also cleaned the cams and greased them.
I also tried adding some lead space to the opener cam and even used tape on the gripper bar to keep the grippers open more, both helped but were not a solution.
(images of the trip lever before and on the opener cam)
I have read the Vanderblog article, ‘Uni 3 – gripper problem at the end of bed’ from September 2, 2022 and it seems like a similar problem.
I was hesitant to make changes to the fulcrum length but it seemed like it might be the cause.
I have looked at the different parts of the press and nothing seems to be bent or worn out and I just wanted to see if anyone had thoughts on what might be the problem, and a possible solution.
I removed the gripper arm and it seemed to be in a good shape and straight.
After adjusting the fulcrum in and out, I decided to take Paul’s advice and took a look at the gripper tips.
The worn gripper tips…
I had 4 replacement grippers from NA Graphics, so I decided to change out the 4 most worn grippers. I lubricated them with graphite and put it all back together. It seems a bit better, but it still seems to be holding onto the paper at the end.
Did you look to see if the cams under the gripper pins are worn and if the cam shaft could benefit from a rotation?
Also, I ran into a different, but similar problem on an SP series press that might be helpful. In my case the grippers weren’t raising very high when I stepped on the pedal. So, I adjusted the fulcrum, but also had to adjust/shorten the linkage that connected the lever to the gripper pedal. The linkage is a rod that is threaded on both ends so that it can be lengthened or shortened.
So in my case, you couldn’t just adjust the fulcrum without also adjust the linkage. I wonder if one of your fulcrum changes would have improved the results at the end of the bed if you had also adjusted the link in the underside so it worked with the gripper pedal.
When the press is ‘relaxed’ and at the feed board, there is 1 3/8″ of stud protruding, and when it is at the end of the bed there is 1 1/4″ protruding.
Before I read your reply concerning worn gripper pins, I decided to try adjusting the fulcrum, which is not that quick of an adjustment to make.
I removed the gripper arm and gave the fulcrum one full turn out, and then reassembled the gripper arm. This resulted in the grippers opening less high at the start and then even more difficulty in removing the paper at the end.
So, I turned the fulcrum back in a full turn to the original position, and then one more full turn in.
This resulted in the paper not being held by the grippers which did not go fully come down.
So, I gave the fulcrum a full turn out back to its original position, and put it all back together.
Afterwards, I realized that it could also be the small limiting screw (allen key screw with a nut) that regulates the travel of trip lever, and that it could be why the paper was not gripped when I had turned the fulcrum out a turn.
Can I make half turn adjustments to the fulcrum and then adjust the limiting (allen) screw just below the fulcrum?
The fulcrum seems to be symmetrical, it would just put the screw on the other side.
Thanks for confirming that, Gunars.
I just pulled the rear side cover off a healthy Uni I here at The Arm and I count the same number of exposed threads on my press as on the fulcrum in your photo.
When the assembly is relaxed at the feed board end, there is 1 1/2 inches of stud protruding from the cylinder. When it is fully compressed at the end of the print stroke with grippers open, it measures 1 3/16 exposed. How does this compare to your press?
Yes, I have tried the wedge in both the short and the long positions, but I still have the same resistance in removing the paper at the end of the bed.
It appears to me that in the photo you are placing the wedge in the “short trip” position. This will also make the grippers open and close earlier, not at the bed end. Try moving it further to the next set of holes nearer the bed end.
Your examination is quite thorough. The fulcrum screw appears to be in the original position compared to the manual (Sheet 190-A). But before making that adjustment, take another look at the bottom of the gripper pins. Any dents or flat spots on both the pins and cams can hinder the grippers from lifting adequately. (This can be accompanied by a thunking sound as the cam pushes against a flat spot.) Although the wear may not be severe enough to weaken the lift at the feed board, it may hinder the lift at the opener cam at the end of the bed. If you do find wear on the pins or cams, rotate either to create fresh contact between them. The gripper pins will likely be more worn than the cams, and replacements are available from NA Graphics.