SP-15 new rollers/image problems

roller image

I just replaced the rollers on my SP-15 and am having trouble printing the first time out. The rollers were purchased from another press owner, but were new and unused, still in original NA Graphics packing and boxes. This was the first time I’d changed the rollers but didn’t encounter any difficulties with changing over the bearing blocks, gear, etc. I’m using a boxcar base and photopolymer plate which I’ve printed from successfully before. The problems I’m having are–

a. The image has a fine darker line of ink around most of the outer edges. I’ve tried 3 different paper stocks and all show the same problem.
b.The front roller has a consistent pattern of blotchy, darker areas of ink, looks sort of like skid marks. The back roller looks normal.
c. After I adjust the rollers to proper height and run just one or two impressions, then recheck roller height, both rollers have shifted. Usually back roller moving up and front roller moving down, both consistent from side to side. I’ve made sure the screws on the blocks are made tight with allen wrench each time.

I never encountered this particular problem with the old rollers. All the oscillation and roller movements look normal to me, but apparently something is off. Any ideas would be most appreciated, thank you!

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Paul Moxon, Moderator
13 years ago

Remember also that only the second half of the hole that the lock screw passes through is threaded. This is what allows the split sections to squeeze together without stripping the threads.

Eric Holub
Editor
13 years ago

Loose roller adjustments are pretty common on the SP-15.
Can you still turn the adjusting knobs when the locking screws are tightened? Cleaning the threads of both the knob and block may help (especially if oil has gotten in there), and you might try some teflon plumbers tape around the threads. At SFCB they put marks on the knobs to indicate whenever there is movement.
It has also been suggested that widening the slot mightd allow a tighter grip on the adjusting mechanism.

Fritz Klinke
Admin
13 years ago

You indicated a previous problem with your old set of rollers on an October 29, 2008 posting–and these are replacement rollers? If you could email me (nagraph@ekiva.net) with the name of who you bought the press from, I could see how recent these rollers are. We normally ship rollers direct from the roller maker, so I’m curious about the NA Graphics packaging. Those splotches are not normal on new rollers, but I think they are unrelated to your inking problem. If you can switch the gear from one roller to the other, you could try reversing the rollers to see if that does anything. For some time now, on new SP-15 cores, we have supplied all rollers machined for use with the gear and originally Vandercook saved a few pennies by providing 2 different cores, one plain and one for the gear.

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