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

  • HP 7475A Plotter: Ceramic Tip Pen Autopsy

    It turns out that the ceramic-tip plotter pens don’t come apart at the top of the flange as I expected. Instead, there’s a snug-fitting plug with a tapered top and an invisible joint at the end of the body tube:

    HP7475A Plotter - ceramic pen - disassembled
    HP7475A Plotter – ceramic pen – disassembled

    Refilling a pair of defunct black ceramic pens didn’t bring them back to life: an ample supply of fresh black ink never made it from the fluff to the nib. Soaking the nibs + fiber shafts in 10% ethanol for a day created an unappetizing black vodka shot that did nothing to get the ink where it needed to be.

    The right time to refill those pens would have been, oh, probably a decade or two ago…

    Some stuff, you just gotta throw out!