Merge PDF Files

This page provides a detailed explanation of the way I merge and edit PDF files to be "printed" by a laser engraver.

Export PDF files

At this point, we should have a finished SketchUp model in sample_m.skp. Now, we get to export various combinations of its layers as PDF. How this is done will depend on the version of SketchUp you have. See the Export PDF page for details.

Prepare a USB drive

  • plug in a USB drive (on Mac)
  • copy the PDF files onto it
  • unmount the drive, then unplug it

Edit PDF for printing

Initial setup

  • plug in the USB drive (on PC)
  • open Adobe Illustrator
  • use Edit > Preferences > Units to set General to inches
  • use Window > Color to set the palette to RGB

Workaround workaround

If you used the OSX "Save as PDF" workaround, you'll need to work around some oddities in the files it creates:

  • open the file; select all (ctrl-A)
  • right click; choose "Release Clipping Mask"
  • select and delete the enclosing rectangle

Tweak input files

The scaling on PDF files can change on import to Illustrator. After fixing this (using the 11" width of the edge rectangle), we kill off superfluous edges, play games with the fill and stroke, etc.

These notes are based on the use of Adobe Illustrator CC (2015.2.0 Release) for editing and Adobe Illustrator 5 for use with the TechShop's laser engraver. So, PDF files should be saved in Acrobat 5 (PDF 1.4) format.

Cells

  • open sample_ec.pdf (Edges, Cells)
  • if need be, do workaround workaround
  • select all and lock the W--H transform
  • set W to 11" (H should now be 8.5")
  • fit artboard to just outside Edges
  • do View > Fit All in Window
  • kill off edges; select all
  • set fill color (black) and stroke (nil)
  • save as sample_c.pdf (Cells)

Edges, Holes

  • open sample_eh.pdf (Edges, Holes) in Layer 1
  • if need be, do workaround workaround
  • select all and lock the W--H transform
  • set W to 11" (H should now be 8.5")
  • fit artboard to just outside Edges
  • do View > Fit All in Window
  • select all; set stroke (0.001)
  • save as sample_eh_e.pdf

Cells, Lines

  • open sample_elr.pdf (Edges, Lines, Rects)
  • if need be, do workaround workaround
  • select all and lock the W--H transform
  • set W to 11" (H should now be 8.5")
  • fit artboard to just outside Edges
  • do View > Fit All in Window
  • select all; set stroke (2 pt)
  • kill off edges
  • save as sample_lr.pdf (Lines, Rects)
  • save as sample_cl.pdf (Cells, Lines)

  • switch to sample_c.pdf (Cells)
  • select all; copy
  • switch to sample_cl.pdf (Cells, Lines)
  • paste and align braille cells; save

Handle relief engraving

We want to engrave everything that is white in the original PDF file, leaving the black parts alone. Epilog's "rubber stamp" mode looks perfect for this, but it isn't supported on the Fusion 120 model (sigh). So, we need to "invert" the colors:

  • set the fill color to white
  • for each input rectangle:
    • create a covering rectangle
    • do Object > Arrange > Send to Back
  • select all
  • do Edit > Edit Colors > Invert Colors
  • save; select all; copy

Create a "combo" document

  • switch to sample_eh_e.pdf (Edges, Holes)
  • create Layer 2
  • paste and align Cells and Lines
  • save as sample_lc.pdf (Laser Combo)

Tweak the Artboard

  • select the Artboard tool
  • set H & W to match the engraver
    (e.g., 24" W x 18" H, 32" W x 20" H)
  • move content to the upper left corner
  • save as sample_lc.pdf (Laser Combo)


This wiki page is maintained by Rich Morin, an independent consultant specializing in software design, development, and documentation. Please feel free to email comments, inquiries, suggestions, etc!

Topic revision: r19 - 18 Jan 2016, RichMorin
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