Inking issues on SP15

We’re completing the rebuild of an SP15 that was begun by someone else (who is now deceased, so we can’t ask them questions) and we are running into some challenges with the inking system.

We were trying to set the rollers to the lightest stripe possible for photopolymer printing, which we did with the press in print mode. But when we tried to ink up the plate in trip mode, parts of the plate were not inking up at all. So we re-checked the stripes, and we discovered that the stripes were different on trip and print, not a good sign. And especially confounding, after shifting from print to trip, the front (press bed side) roller kept basically the same stripe, but the rear (geared) roller’s stripe disappeared, first on the non-op side, and by the end of the press bed, all the way across. Also at the end of the bed, the stripe on the non-geared roller had disappeared as well, but only on the non-op side.

So then we tested the stripes all over the press bed. We noticed the stripe fluctuated at different points on the press bed on both rollers, on both operator and non-operator sides of each roller, and changing in an unpredictable way between both rollers. Enough to drive you crazy.

The form rollers we started with were slightly worn, but we tested for flat spots by lightly rolling the rollers on the press bed while shining a light behind, and saw no gaps. We also tried manually rotating the rollers while mounted on the press, with a light aimed at the top edge to see if we could detect any fluctuation in the projected shadow. We didn’t see any variation there, so it seems like the rollers are adequately concentric. And to add to the confusion, we had a second, fresh out of the box set of rollers (old, but unused), which we installed, and those displayed similar issues, overly heavy stripes on both sides of the geared form near the gripper, becoming much more acceptable over the rest of the bed. And similar to the first set of rollers, heavier stripes in print than in trip.

So, we tried adjusting the top carriage bearings per Fritz Klinke’s instructions in Moxon’s Vandercook book (putting a 0.003 mylar strip between bearings and rails, tightening, then rolling carriage off the mylar). We did nothing to the lower (underrail) bearings. This adjustment resulted in a slightly more even impression (nonop side was ever so slightly lighter to begin with) and the carriage seems tighter to the rails in general, but most importantly, the form roller stripes are as erratic as they were before.

Any insight you might offer will be MUCH appreciated!
Grendl.

Inking issues on SP15

3 thoughts on “Inking issues on SP15

  • September 27, 2018 at 9:34 pm
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    Yes, this method does recommend less clearance on the top front bearing than what Fritz suggested. He was actually referring the under rails .

    The terms “breaking” and “holding” refers to the shim or feeler gauge being either free or held by the bearing and rail.

    Checking with a light does mean shining a light between the cylinder bearers and the rails.

    Sorry, I don’t have any photos.

  • September 27, 2018 at 1:34 pm
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    Thanks for the reply, Paul, very helpful, especially the part about keeping the carriage side plate parallel to the bed bearer. Could you clarify what you mean about the cylinder “breaking” and “holding” (what is it holding to?), and could you also elaborate on checking with a light? Do you mean shining a light between the cylinder bearers and the rails, or something else? Finally, are you recommending even less clearance on the top front bearing than Fritz suggests?

    If you have photos of any of these steps, maybe that would help.
    Thank you!
    Grendl.

  • September 27, 2018 at 10:00 am
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    Uneven wear on the under rails can greatly complicate bearing addjutment. Here’s a method that I’ve used, adapted from notes written by a Vandercook technician (possibly former Vndersons General Manager Gene Wenderski):

    Loosen and back off top front bearing so it will not interfere with the bed bearer when adjusting impression. Shift print/trip lever to print mode and move carriage to the center of the bed. Impression is set by tightening the lower impression bearings, while maintaining 0.007″ clearance between the rear (non eccentric) top bearings and the bed bearers. The carriage side plate must be kept parallel to the bed bearer (check with a magnetic spirit level on bottom surface). Impression is correct when checking with a light between bearers if the cylinder holds at 0.006″ and breaks at 0.008″. Adjust top front bearing for 0.001″ to 0.002″ clearance.

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