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 Paul 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!

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Grendl, with SPs, the upper carriage bearings support the carriage when it is in trip mode, and the lower bearings hold the carriage down while in print mode. When both are adjusted correctly, the rollers will be at the same level in both trip and print modes. I would consider the lower bearings the starting point.
Balancing them—and also keeping the carriage level—is a finicky process. Wear on the bed bearers can also be a factor. Is this press at CCSF, or…?

Hi Eric, thanks so much for your reply. This is super helpful - I was confused about the role each set of bearings played. Would you recommend setting the lower bearings the same way and to the same specs as the top carriage bearings (tightened with an 0.003” strip between bearings and rails as per Fritz K. in Paul Moxon’s book)? Or do you recommend a different approach?

Thanks again,

PS no, this press is not at CCSF, it’s in Oakland.

I’d recommend getting a set of metal feeler gauges, preferably the longer 6” length. eBay or the flea market should produce some inexpensive used ones, just be sure the .003” feeler is in good shape.

Hello Eric et al, we had to take a break from this project and are now back on the case.

When attempting to adjust the bearings, we have run into some seemingly contradictory information and are looking for clarification. In Moxon’s book, Vandercook Presses, on page 10 he quotes Fritz K. who reports: “We have typically set the impression bearings with the cylinder on print positioned in the middle of the bed.”

Moxon goes on to recommend Gerald Lange’s article “Adjusting Cylinder Carriage Bearings” hosted on the Vanderblog website. In his article, Lange states: ” The top bearings work in conjunction with the roller height adjustments. Turning the eccentric to raise the bearings upward will cause the rollers on that side of the carriage to drop (downward movement). These bearings are adjusted on “print” mode. The bottom bearings control the amount of impression. Turning the eccentric to raise the bearings upward reduces the play in the cylinder, thus increasing impression. These bearings are adjusted in “trip” mode (off impression).”

So, my questions:
Is the adjustment to the underrail/bottom/impression bearings made on trip or print?
Is the adjustment to the top bearings made on trip or print?

Please advise! This adjustment is so fussy, it’s been driving us nuts, and then to find that we may have done it all wrong… ARGH!!!

Thank you!

The bearings under the rails are the ones that hold the carriage down under impression, so they are adjusted in “print”.
The upper bearings support the carriage when it is in “trip”, so I’d adjust it there so that it is at exactly the same height as when in print. That is the level of the return stroke, unless short-rolled (not a good habit). And be careful to maintain carriage as level and parallel to the bed.
This is for SP series. Not all Vandercooks have this design.

Thanks for clarifying this, Eric. Very helpful!

Now, we just wondering what function the bearings perform, exactly (maybe this would help us understand why we are making the adjustments we are making). Are they just there to stabilize the carriage and keep it from wobbling, when in print (and the main load is carried by the bearers)?

And when in trip, are the four top bearings the only thing supporting the carriage (in which case, it seems like it would be impossible to get any gap when checking in trip, which is why we’re not sure we understand how they work…)

Thanks Eric!

The lower bearings are set to prevent cylinder bear-off during impression.
The upper bearings are supports for the carriage when off impression. Their adjustment is not to a gap, but is judged by the level of the form rollers. When they are at exactly the same height—by roller gauge stripe—as when on impression, you have them correct.