Grippers snap closed when cylinder is at feed board…

I am trying to work out the quirks in one of my 320G presses and the thing that is bothering me the most is that the grippers are closing when the cylinder reaches the feed board. The gripper pedal won’t open them at this point. The gripper bar stops at the proper vertical orientation, but I think it may be closer to the edge of the feed board than it is meant to be. Should I assume that the cylinder is meshed one tooth off and needs to be rolled off the end, reset, and the bumper springs readjusted to make it stop vertical further to the right? The other press isn’t much help because the cylinder is even further out of its proper meshed position. It should be a bit of a chore to roll these off the end of the bed.

Daniel Morris
The Arm Letterpress
Brooklyn, NY

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Eric Holub
17 years ago

If the 320G is similar to the 325G, the feedboard is at a 5-degree angle at the lip, and the top of the gripper bar is parallel to that, which is one tooth forward of vertical.
There is some adjustment with the bumper springs, but the rest position is determined more by the gripper trip assembly (far side, visible when cylinder is moved forward). On a G model, the roller rides over the auto wedge portion and comes to rest behind it. From there the footpedal activates another rod that raises the grippers from the rest position.
I’d check that all parts of the gripper trip mechanism are present and functional and lubricated. I have a particular problem with the spring that holds the wedge back. The original was too weak, and my replacement keeps breaking. Click, boing, snap. Bend a new hook from the stub, and back to work.
–Eric Holub, SF

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