Re: [PPLetterpress] Building up roller tracks
- In a message dated 10/10/2003 carolealdrich@... writes:
<< to build up the roller tracks. ... the tape compresses over time....
I also had a problem with uneven inking... >>
Regarding using tape to build up the tracks on your Pilot, NA Graphics sells
a tape that doesn't have the same compression problem as masking tape -- or
you can just live with the continuing compromise of adjustment, which is a major
part of letterpress printing anyhow!
(The use of tape to build up the tracks is the easiest solution to the
problem of rollers hitting the type too hard, which can force the ink off the center
of the type (leaving a light spot in the center of each letter and sometimes
a halo of ink around the edges of the letter). When the roller hits too hard,
it may look like there is not enough ink though the opposite may be true!)
The "inking problem" you describe could be any of several things. You may
just have a roller that has a low spot, so it works its way around erratically
under-inking or over-inking depending on how you try to adjust. The answer to
that is to get new rollers!
Or it may be actually a problem in the packing. The Pilot press is hinged
closely at the bottom, and if you use a large form and thus need to have rather
heavy packing, the bottom of the form hits harder than the top. Trying to
adjust for this difference just by adding packing can create odd pressure
differences across the form. And sometimes these seem to shift around as you print or
try to adjust further. It can look like an inking problem.
I'd start by taking out the packing and then working up slowly to a light
impression. Then you can see more easily if there is a heavier hit at the bottom
of the form, and then adjust the pressure bolts on the back of the platen as
you bring the packing up to where you want it.
A smaller form may not show these kinds of problem, even with the same
adjustments -- always a tendancy to work beyond the natural limits of the machinery.
Any how, I hope these thoughts might help.
Best wishes, Tom
Now It's Up To You Publications
157 S. Logan, Denver CO 80209
> hmmm...Stop! the vinegar will eat the polymer right up. That's what one is to use
> may be i'll dunk a piece of polymer into vinegar to see if it does anything...
> report back).
when cleaning platemaking equipment. It just melts the stuff.