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Re: [PPLetterpress] Packing questions

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  • typetom@aol.com
    In a message dated 8/12/2007, g_mtch@yahoo.ca writes: ...I ve read that if I overpack the Pilot you ll get more impression at the bottom of the form than the
    Message 1 of 3 , Aug 12, 2007
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      In a message dated 8/12/2007, g_mtch@... writes:

      ...I've read that if I overpack the Pilot you'll get more impression at the
      bottom of the form than the top, so instead of overpacking, I should put some
      sheets behind the chase...



      Hello g_mtch,
      The larger the press, the easier it would be to get what you want. The Pilot
      will be working at its limits to get a deep impression. The reason the Pilot
      will have more impression at the bottom than the top is because the platen
      is hinged rather close to the bed (on the 8x12 or 10x15, the hinge is all the
      way down at the floor). This means that as you add packing it will hit the
      bottom edge before the top edge can come together.

      Thus you will need to loosen the platen bolts at the bottom edge or tighten
      them at the top, to make allowance for the additional packing and the way the
      hinge moves the platen. This adjustment is rarely needed on the larger
      platen presses, but is frequently necessary on small presses as the packing is
      increased.

      (The situation will be the same, whether you add packing to the tympan or
      whether you add packing between the type-form and the bed. Both kinds of
      packing increase the print impression by positioning the type and the paper closer
      together, though packing behind the type also moves the type forward to hit
      the rollers harder, thus perhaps causing too much roller pressure over the
      form.)

      Your best bet will be to give it a try! I'd start with little or no
      packing, with just a ghost of an impression, and then add sheets (of whatever
      material) and watch the results. As the impression is made stronger, at some point
      you will notice the upper part of the image will become weaker as the bottom
      edge has more impression. That's the limit of adding packing without making
      adjustment by changing the angle of the platen. The answer is to experiment
      and keep your eyes open to what is happening!
      Best wishes,
      Tom

      Tom Parson
      Now It's Up To You Publications
      157 S. Logan, Denver CO 80209
      (303) 777-8951 home
      (720) 480-5358 cell phone
      http://members.aol.com/typetom



      ************************************** Get a sneak peek of the all-new AOL at
      http://discover.aol.com/memed/aolcom30tour


      [Non-text portions of this message have been removed]
    • Scott Rubel
      But then, putting sheets behind the form, you have to raise the rollers, too, plus it doesn t solve the problem of the altered relationship of the form with
      Message 2 of 3 , Aug 12, 2007
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        But then, putting sheets behind the form, you have to raise the
        rollers, too, plus it doesn't solve the problem of the altered
        relationship of the form with the platen. These are meant to be
        parallel when they come into contact at an exact point in each cycle.
        If you raise the form or put too much packing in, or both, the point
        of contact changes from the intention of the design of the press, and
        therefore will apply more pressure at the bottom than at the top. You
        can change this with careful makeready, or, if you intend to operate
        this way all the time, readjust the platen. This is just another way
        of saying what's already been said here, but the main point is that
        raising the form will cause the same problem, plus another set of
        problems.

        --Scott

        On Aug 12, 2007, at 11:56 AM, typetom@... wrote:

        >
        > In a message dated 8/12/2007, g_mtch@... writes:
        >
        > ...I've read that if I overpack the Pilot you'll get more
        > impression at the
        > bottom of the form than the top, so instead of overpacking, I
        > should put some
        > sheets behind the chase...
        >
        >
        >
        > Hello g_mtch,
        > The larger the press, the easier it would be to get what you want.
        > The Pilot
        > will be working at its limits to get a deep impression. The reason
        > the Pilot
        > will have more impression at the bottom than the top is because
        > the platen
        > is hinged rather close to the bed (on the 8x12 or 10x15, the hinge
        > is all the
        > way down at the floor). This means that as you add packing it will
        > hit the
        > bottom edge before the top edge can come together.
        >
        > Thus you will need to loosen the platen bolts at the bottom edge
        > or tighten
        > them at the top, to make allowance for the additional packing and
        > the way the
        > hinge moves the platen. This adjustment is rarely needed on the
        > larger
        > platen presses, but is frequently necessary on small presses as
        > the packing is
        > increased.
        >
        > (The situation will be the same, whether you add packing to the
        > tympan or
        > whether you add packing between the type-form and the bed. Both
        > kinds of
        > packing increase the print impression by positioning the type and
        > the paper closer
        > together, though packing behind the type also moves the type
        > forward to hit
        > the rollers harder, thus perhaps causing too much roller pressure
        > over the
        > form.)
        >
        > Your best bet will be to give it a try! I'd start with little or no
        > packing, with just a ghost of an impression, and then add sheets
        > (of whatever
        > material) and watch the results. As the impression is made
        > stronger, at some point
        > you will notice the upper part of the image will become weaker as
        > the bottom
        > edge has more impression. That's the limit of adding packing
        > without making
        > adjustment by changing the angle of the platen. The answer is to
        > experiment
        > and keep your eyes open to what is happening!
        > Best wishes,
        > Tom
        >
        > Tom Parson
        > Now It's Up To You Publications
        > 157 S. Logan, Denver CO 80209
        > (303) 777-8951 home
        > (720) 480-5358 cell phone
        > http://members.aol.com/typetom
        >
        >
        >
        > ************************************** Get a sneak peek of the all-
        > new AOL at
        > http://discover.aol.com/memed/aolcom30tour
        >
        >
        > [Non-text portions of this message have been removed]
        >
        >
        >
        >
        > Yahoo! Groups Links
        >
        >
        >
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