The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

The New Hotness

  • CD/DVD Data Destruction: Mariner’s Compass Coasters

    Snap all the Mariner’s Compass inset layers together into a single LightBurn layout:

    Mariners Compass - stacked insets - LB layout
    Mariners Compass – stacked insets – LB layout

    Scale it to 120 mm OD, delete the innermost circles under 15 mm diameter, then go wreck yourself some CDs and DVDs:

    Mariners Compass Coaster - CD DVD tests
    Mariners Compass Coaster – CD DVD tests

    Those were test pieces to figure out speeds and powers starting from the polycarbonate settings used for the Guilloché DVD now serving as a coaster atop the laser.

    When you’re looking to destroy the surface, then pretty doesn’t matter, but they come out surprisingly nice in a techie sort of way:

    Mariners Compass Coaster - CD clear side test
    Mariners Compass Coaster – CD clear side test

    That’s burned into the clear side of the CD before I figured out how to control the power at the starting points.

    This CD-R came out a nice silver, with the tracks burned into the data / label side:

    Mariners Compass Coaster - CD-R test
    Mariners Compass Coaster – CD-R test

    The polycarb tends to scorch & discolor at the starting point of each polygon, where the laser dwells momentarily after lighting up. Avoiding that requires setting the minimum layer power 1% below the Ruida controller’s minimum firing power. In this case, running the layer at 7% minimum with the controller set to fire at 8% completely eliminates the scorches.

    The maximum power is about 10% for the clear side. The data side requires only 10% for lightly coated CD-R / CD-RW and maybe 25% for the heavily inked labels of pressed CDs (like the Dell reinstallation CD in the first picture). It helps to start with a vast supply of unwanted discs.

    Suiting action to words:

    Mariners Compass Coaster - CD data side finished
    Mariners Compass Coaster – CD data side finished

    That’s a CD-R wrecked on the data side, stuck to an MDF disk with a cheap craft adhesive sheet and a cork disk wood-glued to the bottom. Carefully hidden here, the central hole sports a 15 mm chipboard disk contrasting horribly with the CD; it cannot be more than 1 mm thick to avoid having it stick up beyond the plastic surface and chipboard is what I have in that thickness.

    The advantages of wrecking the data side:

    • Leaving the clear side smooth, so crud won’t accumulate / grow in the grooves
    • Absolutely, positively, utterly destroying the data track

    The advantages of wrecking the clear side:

    • Maybe breaking the seal formed by condensation under the mug / glass / cup
    • Leaving the data side intact, so the coating won’t disintegrate and peel off the adhesive

    In either case, however, I’m sure the data is gone.