The grippers work fine on our SP-15 when we use the foot pedal to insert the paper, but they do not properly release the paper at the end of the print. Other than adding some shims behind the bracket that activates the gripper lever at the end of the print action, is there another method of adjusting the grippers?
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Working from memory without an SP nearby. I stand corrected: the flange (what John and Nancy call the bracket), should still raise the grippers whether or not the cyinder trips at the end of the print stroke.
I do recall working on one SP-15 where I adjusted the position of the flange to make the grippers raise at the end of the print stroke. It had slotted holes for the screws that fastened it to the side of the bed that allowed it to be moved forward or back.
When I had an SP-20, one of the trip springs did break, and it was obvious because one side of the cylinder was stuck on impression while the other side moved up and down normally. I didn’t need to break the spring like the manual shows, I just pulled the stub of the spring off with a Linotype mat hook (a long, thin piece of spring steel with a small hook at the end).
I don’t see that there would be any effect on the gripper mechanism from that problem though. But my SP-20 also came with a custom-made piece that made the grippers open wider at the end. On many Vandercooks the roller-bearing on the gripper lever is moved by a wedge on the side of the press, but on the SP-20 there is a flange. In this case, the previous owners made a piece that slid over the existing flange; it started a couple inches closer in, and I think was just slightly wider. That made the grippers open slightly sooner and a bit wider. Sorry, I don’t have any pictures or measurements.
First check that the nylon trip rollers are present on both sides at the end of the bed. This is what contacts the trip arm inside the carriage. Replacements available from “NA Graphics”:http://nagraph.com.
Next, using a flashlight, examine the space between the cylinder gear and the outer carriage housing. It may simply be that the trip arm assembly is gummed-up. If so, shoot some canned air into this space to blow out the lint and cobwebs, then spray some WD40 to relubricate. See Sheet 287-A of your manual.
If this doesn’t help, then you may have a broken trip spring. The springs can be replaced, but first you have to break the loop end of the spring as descibed on Sheet 302. Please let us know how this turns out.