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12870Re: Laser Engraved Photopolymer Plates

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  • Gerald Lange
    Oct 22, 2011
      Scott

      I suspect that if cut just short of the floor of the plate rather than down to the backing there would be no problem with the steel reflecting. A more significant concern would be cutting through the pre-exposed floor as plate stability would be sacrificed. Actually, with this technique, the thinner the plate the better. All that

      I assume the identity of the plates themselves and the correct timing for the exposure is a minor problem. 1200 dpi is still not good enough, basically high-end laser printer quality. Imagesetter quality at a minimum of 2400 dpi would be needed to match current film based exposure.

      A major concern would be maintaining relative reverse relief depth, which is fairly uniform when exposing photopolymer plates specified for letterpress applications, no matter what the thickness of plate. For instance, the relief depth of the counter of a small point size lowercase e or o is not going to be open to the depth of the floor of the plate. It is halted with maximum exposure at a specific range, about .30 mm; relief depth is not uniform [which is actually the best technical argument refuting the practice of extreme impression]. I don't see how this could be controlled with a laser cutter.

      Gerald
      http://BielerPress.blogspot.com


      --- In PPLetterpress@yahoogroups.com, Scott Rubel <scott@...> wrote:
      >
      > The website days it goes to 1200 dpi. If the coordinate tracking is
      > accurate as it cuts, that should render pretty good six point type.
      >
      > It is hard to tell the quality of the laser, but I think I will ask
      > them for a sample of steel backed polymer. I wonder how that works
      > without the steel acting like a mirror.
      >
      > These laser beams can be unbelievable thin, if they are high quality.
      > I work at a place where we make giant cameras for giant telescopes,
      > and we order custom "slit masks" which are large sheets of aluminum
      > with thousands of precision placed cuts in them. The cuts aren't much
      > thicker than a hair, and you would think the laser is just moving
      > along a path and cutting the slit, but in reality it cuts out the
      > shape of the slit and almost microscopic blanks fall out of the metal
      > every time a slit is cut. So if this Epilog Legend 36EXT machine is
      > high quality, I would think six point type should work fine.
      >
      > --Scott
      >
      > On Oct 22, 2011, at 2:31 PM, Peter Fraterdeus wrote:
      >
      > >
      > >
      > > I'm interested in how well these desktop lasers can render type
      > > below 6 points.
      > > We run a LOT of business cards, many of which were designed for
      > > mice, apparently ;-)
      > >
      > > Not ready to get rid of my Interflex platemaker yet!
      > >
      > > P
      > >
      > > Peter Fraterdeus
      > > Exquisite letterpress takes time™
      > > http://slowprint.com/
      > > tweet: @slowprint
      > >
      > > IdeasWords : Idea Swords
      > > Communication Strategy
      > > Semiotx.com @ideaswords
      > >
      > > On 22 Oct 2011, at 2:40 PM, Silber MaiKätzchen wrote:
      > >
      > >>
      > >>
      > >> What number, thickness and brand plate are you
      > >> using?
      > >>
      > >> I use a Epilog Legend 36EXT with a 120W laser, I
      > >> am using a plate now that I like that comes with
      > >> a steel or poly backing. It takes me eight minutes
      > >> to do a 6X9" plate from Cobalt, their AccuLaze in
      > >> 11 pt.
      > >>
      > >> MaiKätzchen
      > >>
      > >> Dum loquimur, fugerit invida Aetas:
      > >> Carpe diem!
      > >> quam minimum credula postero!
      > >>
      > >> Horace
      > >> Odes Book I
      > >>
      > >>
      > >> From: Gerald Lange <Bieler@...>
      > >> To: PPLetterpress@yahoogroups.com
      > >> Sent: Fri, October 21, 2011 11:50:01 PM
      > >> Subject: [PPLetterpress] RE: Laser Engraved Photopolymer Plates
      > >>
      > >> Of potential interest is this thread from Briar Press Discussions:
      > >>
      > >> http://www.briarpress.org/27881
      > >>
      > >> Gerald
      > >>
      > >>
      > >>
      > >> ------------------------------------
      > >>
      > >> Yahoo! Groups Links
      > >>
      > >>
      > >>
      > >>
      > >>
      > >
      > >
      > >
      > >
      >
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