Imbalance of Ink of Drum and Rollers of SP-15

I noticed that the ink on the drum and rollers on my SP-15 bunch to one side, so I get uneven ink coverage when printing. I’m attaching a couple of photos. You’ll see that on the right side is where it’s light and almost translucent, and the ink tends to bunch on the left side where it is much more opaque.
I tested printing blind to make sure that it’s not a problem with impression so I’m not sure if it’s an imbalance in the bearings or if the drum is uneven.
Would I be checking for the same things? What is a spirit level?
Another issue that is recurring is that the roller heights keep changing, even though I adjust them to the right height. I spend so much time getting it right but after a while, it’s off again. Is that normal? I tighten the screws but am wondering if I should replace these screws? They don’t seem to be loose as I loosen them to adjust and tighten them again.
Would really appreciate your thoughts.
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Paul Moxon, Moderator
28 days ago

A spirit level is a tool designed to indicate whether a surface is horizontal or vertical. Use it to compare the drum with the bed. If the drum needs to be leveled, place thin shims (paper or Mylar) on one of the brackets before reinstalling the drum. Punch a hole in the shims to allow the screw to pass through the drum shaft and bracket.

If this adjustment doesn’t help, the problem may be:

  • a twisted oscillator frame.
  • debris in the holes for the adjusting post in the side plate.
  • carriage bearings out of adjustment.

Ernst Shaefer developed his own carriage bearing adjustment method(it will be featured in the next edition of my maintenance book): Adjustments must be made on each side at the same time (best with two people) and pressed away from the wall:

With the carriage at the feed board, loosen the large nuts and small lock bolts on the top front and bottom eccentric bearings.

Shift the print/lever to “print” and roll the carriage to the middle of bed. 

Push down on the top rear fixed bearing tie rod while adjusting the top front eccentric bearings. All bearings and the cylinder bearers should touch the bed bearers. 

Check that the side plates are parallel to the bed.

Return the carriage to the feed board, shift to “trip,” and roll it to the middle of the bed. The top bearings should contact the bed bearers, while the impression cylinder does not. 

Return the carriage to the feed board and shift to “print.”

Roll the carriage to the middle of the bed and mark the position of the two adjustable top bearings and the cylinder at the bed bearer.

Place 0.003″ feeler gauges at the marked areas and roll the carriage over them. 

Turn the adjusting levers so the bottom rear and front eccentric bearings snugly contact the underrails.

Roll the cylinder off the feeler gauges to produce a 0.003″ tolerance for the bottom bearings against the underrails.

Use a roller setting gauge to check that inking is constant in print and trip.  

Test that impression is even over the whole bed.

The bottom bearings should be “loose” in “trip” and tight in “print.”

Last edited 28 days ago by Paul Moxon, Moderator
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