I am frustrated with my print quality on my SP15.
I am using photopolymer plates to print personalized note cards with small type. The type is very uncrisp. It looks like the ink is pooling on the edges and bleeding outward, while the inner part of the text has less ink.
I just switched to using Van Son Soy ink and am printing on Lettra 110# Cover. Could this be the soy ink?
My roller height is perfect. The rollers are clean. My packing is fine. My impression is good. I am not overinking the press….
What the heck is going on?
Sara’s idea is a good one. Loose gears are probably the most common but unnoticed problem I have seen. That gear drives the whole inking pyramid, when it isn’t in contact with the drum (or is this a manual SP-15? That would really suffer from a loose gear).
Some of the most experienced—and accomplished—Vandercook operators working today have already commented. They’ve approached it from nearly every angle, the combination of materials you presented are some varied the each one are worth close examination. I would still like to see a close up photo of the ink on paper.
But to elaborate on Sara’s suggestion: the SP15 form roller gear has two set screws on its collar that should tightened against the core. Check this regularly and make sure that the gear is aligned with the rack. The gear could be slightly reamed which would allow the rollers have a little play to slide in places over the form. An indication of this is that the gear will wobble as it travels the rack. In this case the gear should be replaced. And It’s been noted elsewhere that the rubber should be 2.5″ in diameter.
Thank you all for the input.
Sara, I think you’ve identified what’s happening on my press.
I’ve searched the archives, but I don’t see any specific info on the gear wheel issue.
Paul, can you point me in the right direction or otherwise give me a tutorial?
Thanks a million!!!
Something simple to eliminate before you go to heroic measures is to check the gear wheel. When the gear wheel turns it should engage the form roller. It’s not unusual for the set screw holding the gear wheel to the roller to come loose. When this happens the gear wheel spins around the form roller core, rather than turning the roller. If this is going on with your press, the form rollers are staying in a fixed position as you print. The ink is being spread/scraped across the surface of your plate.
This is a regular issue on our classroom SP-15. I think it’s been covered before on the V-blog, you might find more detailed tips in the archives.
Good luck! Sara L.
Not sure I can add much more here except to ask what is your experience with this particular press? It sounds like you might need a bearing adjustment or you should use roller supports in your form, that will eliminate the unevenness.
Note the roller height measurements are somewhat meaningless. They will differ from point to point on the press bed. They are also commonly thought to be for determining the amount of pressure that the rollers exert on the form. This is true but only in an ideal situation. As these presses age and as the rollers age things change. Particularly of concern is the pressure relationship of the rubber rollers to the steel rollers. This can only be determined by getting to know your press. Your roller height needs might vary and have to be adjusted per what is working well for you. There is no rote way to do this.
Is there any chance your bed plate is missing (a steel sheet that lays on the bed, under your polymer base and/or type)?
If you’re setting your roller height without a bed plate, then the rollers are too low, your cylinder would be over-packed to compensate, and the press would be out of sync with itself. I once tried to print on a press not knowing the bed plate was missing, and had only terrible results from it.
The roller setting gauges are accurate to .918, but rarely are the plate base combinations to the same accuracy. The gauge is the beginning and not the end of setting roller height, and that applies to any press including platens. In my experience, they serve to get both ends of the rollers to the same height from the bed, then the rollers have to be set to the plate or type. And that will be different for a plate with a very small image area to a plate with a large image area, where the rollers may have to be set tighter, or closer to the image area. As rollers age, especially on proof presses, the ends of the rollers tend to swell changing the diameter from the ends to the diameter in the middle and that affects inking to the point that a decently inked image, on larger plates, is not possible.
Then there are the other items already mentioned, and all of this is lumped under the term “makeready,” something that tends to be a mystery mainly to beginning printers, and even some experienced ones.
First, you need to know that your plate is actually type-high (every printer should use a micrometer). Then you need to set your rollers accurately (every Vandercook owner should use a roller-setting gauge), Then you need to ink up the press lightly (soy inks might be loose enough, but stiffer inks–especially rubber base–should be worked wth an ink knfe on the slab before adding to the rollers), and seeing how that prints, and slowly add ink, testing as you go. That’s the only way to see how much ink is too much. You may be starting with too much.
The packing on the press must be checked too. Beaten packing affects print quality, and heavy impression beats the packing, even if it is Kimlon or mylar.
I know you say you aren’t overinking, but that it the first thing I would check. I think overinking is about 70% of the problem most every time. Honestly, sometimes I’ll put as much ink on the press to start with as I think it should have. Then I end up running a complete sheet through the rollers to reduce the amount of ink on the press. That will make it better. I then do it again. And again it is better. Then I’ll do it again and it is right.
Fair to assume you have a roller height gauge?
How was the polymerplate made? How do you know your Form Rollers are set up right?