New Pens For Old Plotters

Finding consumables is an ever-present problem facing anyone working with old computer hardware. Many of these devices ceased manufacture decades ago and what old stock remains is invariably degraded by time. [Retrohax] has encountered it with the pens for an Atari plotter, a machine that uses an ALPS mechanism that appears in more than one 1980s machine. The original pens had dried out beyond the ability to refill, so he takes us through the process of finding replacements.

Sadly there are no equivalent modern pens ripe for modification, so whatever replacement he used would have to involve a little lateral thinking. He thought salvation was at hand in the form of multicolor ballpoint refills of the type where the ink is in an easily cuttable plastic tube. [Retrohax] and was able to make a 3D-printed holder for a cut-down ballpoint refill. Sadly the pressure required for a good line from a ballpoint was much higher than the original pens, so he was back to square one. Then he happened upon gel pens and tried the same trick with a gel pen refill. This gave instant success and should provide a valid technique for more than just this ALPS mechanism.

If you haven’t got a classic plotter to hand, never fear. You can have a go at making your own.

16 thoughts on “New Pens For Old Plotters

  1. That ALPS plotter mechanism was used in a bunch of different plotters in the 8-bit era, most famously the Tandy CGP-115: There’s also an 80-column version which was used in some electronic typewriters — yes, they’d draw the text as you typed, in four colours and a variety of sizes. I’d love to get my hands on one.

    There’s tonnes of resources available, including a source for brass replacements for the horrible little nylon gears which shrink with age and crack, but most importantly it turns out you _can_ get replacement pens. They’re still made because they’re used in some medical equipment, and they’re refillable. See for all the information.

    1. There’s tonnes of resources available, including a source for brass replacements for the horrible little nylon gears which shrink with age and crack…

      Planned obsolescence. Things are designed to last for just as long as they need to bring new models to market.

  2. Not knowing where ALPS stands for, I started to google, only to find out that it is a printer mechanism type of some sort and not just a common abbreviation. Stupid me, I should have known, anyway, I then realized that these mechanisms were also used in Commodore printers and I recall some people having problems with some of the gears splitting. Another website mentions this issue, see the link below as it might be of use to somebody some day.

  3. I’ve been thinking of trying Gel pens in my old Tandy CGP-115 that’s still sitting in my dad’s basement. I had a lot of success with 3D printing Gel pen holders for my HP DraftMaster RS. So much so it has become my daily driver for doing technical drawings again. If anyone wants/needs to make pens for these larger printers, check out my Thingiverse page for them:

    On the topic of these ALPS plotters, I did find a source for new pens a few years ago. I found it listed on a Tandy wiki. They come from a German medical supplier:

    1. That’s cool! Thank you! 😎

      Btw, I still remember how my dad and me once bought such plotter pens and electric calculator pens in a stationery store.
      These stores had about anything related to paper and printing. Including ink ribbons for matrix printers and typewriters.
      If we think of it, it’s rather ironic for a computer person to visit a store focused on pens and typewriters.

    1. Didn’t the Sharp MZ-731 use a similar plotter, too?
      Some pics found here:

      That site has a list of compatible pens:

      Astron MCP-40, MCP-80
      Brother BP-30
      Commodore 1520 bzw. VC-1520
      Canon X-710
      Casio FA-10
      General LBC-1100 Panox, CL-1000
      Gould DS 1604, OS 450
      Loewe PBT 03
      Mattel Aquarius 4 Color Printer/Plotter – Model 4615R
      Mitutoyo Digimatic Miniprozessor, DP-3DX, DP-2,NEC, PC-6022
      National Matsushita AK-P200, AK-P400C, RK-P400C, NDC PC 6022
      Oric MCP-40
      Sharp CE-150, CE-160, CE-161P, CE-516P, CE-515P, MZ-1P01, MZ-1P16, MZ-700, MZ-731, PC-2500, EA-850B, EA-850C, BP 1, BP 2
      Shiruba EB-50, JB-10
      Siemens Oscilla D 1040
      Silver Reed EB50 Color Boy
      Sony PRN-C41
      Tandy Color Printer CGP-115, PC-2
      Texas Instruments HX-1000
      VTech Laser PP 40

  4. Oh! It’s the same mechanism and pens that are used in my old Oric printer! What a memory to hear that sound again! I still have it somewhere, i will have to try that hack… Thanks!

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