C & P inking problem
I recently acquired a C & P 8 x 12 New Series press. After a fair amount of restoration and practice, I’ve almost finished a chapbook and have enjoyed every bit of it. Except for one recurrent problem: after running twenty or thirty copies perfectly, there will suddenly be small areas(four or five words in a a single line) that are printing faintly. Rollers are still adjusted to correct height, impression is unchanged, everything next to the inkless zone is fine. I watched the rollers and am sure they’re not sliding. At one point I thought it was simply that the spot on the roller surfaces was repeatedly touching the exact same area every time and running out of ink. Doesn’t make sense, but in fact when I manually turned the rollers each a half turn before the next imprint, it often cured the problem. I also tried cleaning the type in that area in case some oil had gotten on them. Helped a little. Once that line starts printing again, the problem doesn’t recur…but may happen somewhere else twenty sheets later.
I didn’t replace the rollers…they are rubber and looked pretty decent…with Morgan trucks that are in good condition, capable of fine tuning. The rails are the weakest point…somewhat pitted from corrosion. But I can’t see how that would cause this particular problem.
Any suggestions?
Thanks…..
Either there are low spots on the rollers, or high spots on the expansion trucks (more likely). The problem areas coincide periodically with this result, worst with transparent PMS inks. This may be due to trucks that are over-expanded to compensate for low tracks. For me, solid trucks and careful taping of tracks and trucks solved the problem; or you could just tape the rails and get new rubbers for the trucks.
A test: set the rollers on a flat surface. If the trucks are oversize, you will see a gap under the roller (if not, set them on enough leads to make a gap); see if the gap changes when rolled. Then take off the tricks and support the roller shaft on furniture that leaves a similar gap under the roller. Turn and look for changing gap. If none, then it is the trucks that are eccentric.
parallel i…
That’s an elegant way to distinguish between the two causes…I’ll try it first thing in the morning.
I think your other point is very probable…that it’s when the problems coincide. That would explain the sudden appearance and also disappearance when I rotated the rollers manually.
Thanks ….
offset rollers need to be deglazed every once in a while, why wouldn’t letterpress rollers, i use a deglazer wash on my rollers made by van son, worth a try. good luck dick g.
Post-testing report: It’s the expansion trucks…the rollers themselves are nicely cylindrical. The rubber is probably too old to resist flattening a little against the rails,and then ka-bump, & slightly lift.. I’m moving on toward new metal trucks. Unless I can find a way to replace the rubber. I sort of like those little guys.
Thanks again.
i think na graphics sells new rubbers for morgan trucks. good luck dick g.