HP 7475A Plotter: Ceramic-Tip Pen EOL

Ceramic-tip plotter pens draw wonderfully crisp lines:

Spirograph pattern - black ceramic pen - detail
Spirograph pattern – black ceramic pen – detail

Eventually, though, the fiber tip wears flush with the ceramic shell, becomes slightly indented, and ceases to make its mark in the world:

HP 7475A Plotter - Ceramic pen - worn tip
HP 7475A Plotter – Ceramic pen – worn tip

As the lady says, “Starting from zero, got nothing to lose”, so I applied a fine diamond file around the tip:

HP 7475A Plotter - Ceramic pen - filed tip
HP 7475A Plotter – Ceramic pen – filed tip

Well, all I can say is it seemed like a good idea at the time.

Alas, even the newly exposed fiber didn’t make much of a mark on the paper and, as you’d expect, the ragged ceramic tip dragged painfully across the paper. I assume the fiber had filled with fossilized dry ink.

A New Old Stock bag of fiber-tip pens emerged from the Big Box o’ Pens while I was flailing around:

HP 7475A Plotter - NOS Green pen package
HP 7475A Plotter – NOS Green pen package

I think the “812” in the lower right corner is a date code, most likely early in 1988, so the pens started their lifetime countdown at least three decades ago. They still work, though:

HP 7475A Plotter - NOS Green pens
HP 7475A Plotter – NOS Green pens

The plotter appeared at HV Open’s Mad Science Fair, because everybody loves a plotter!

4 thoughts on “HP 7475A Plotter: Ceramic-Tip Pen EOL

    1. Yeah, and I specifically picked the fine diamond file to get a nice finish. Looks more like a dull chainsaw …

  1. Proud to have contributed to this legacy (or lunacy if you prefer). I didn’t realize how many million miles were left in that machine. Thank you for keeping it going!

    1. It’s a mild obsession (as things go around here), generated several interesting side projects along the way, and definitely smartened me up on algorithmic art. Thanks kindly!

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