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IBM Selectric III Restoration Project

I got myself a Selectric typewriter in a pretty bad shape... This is gonna be a rough ride!

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The IBM Selectric III was one of the finest, most clever inventions in the world of typewriters... It's purely mechanical, driven with an electric motor but no electronic parts, and uses a very characteristic "golf ball" typing element, which is pretty much an equivalent of metal type. The typewriter allows for pressure adjustment to make anything from what would be called "kiss impression" in the world of letterpress printing, to a text with clearly visible impression, though it certainly would take its toll on the typing element's durability.

How I got it:

I found this typewriter for 80PLN on an online classified site, with additional 30PLN for postage (which in fact turned out to be over 60PLN - almost the price of the machine!). After waiting for more than a week, it finally got here; I unpacked it. Here's the video:

There were obvious signs of something going wrong here, the bent correction key being an obvious example. I figured out how to remove the enclosure and take the innards out of it, revealing the beautiful mechanism, as well as lots of nasty deteriorated sponge that will all have to go, and - to my horror - some broken plastic parts, hopefully not essential. I also corrected some dislodged springs and straightened the bent key stem. Yay.

  • It's Gluebricant!

    Keri Szafir12/18/2022 at 09:39 0 comments

    The simple and obvious problems I mentioned before are nothing compared to the fact that this typewriter has been standing for years with no proper maintenance and oiling... Same problem as I once had repairing a vintage record player - the grease became sticky and viscous, turning into glue. So, Gluebricant. Even taking the typing element and cassette off was a problem; it just needed so much force I was afraid to damage the machine's parts. Same with getting the print rod to turn. What is more, the keyboard is not working (keylevers not engaging the interposers), and I've got my suspicions about the cause... There's a clever interlock mechanism named compensator tube, which has slots the interposers go into after they're pressed; this tube is filled with ball bearings with only one interposer's thickness of space left. Whenever an interposer is in the tube, it pushes the ball bearings aside and goes between them, leaving no space for any other interposer, thus locking all else out besides the one for the key currently pressed. Clever, clever. There's an additional interposer for keyboard lock when the typewriter is in the off state (it's operated by the power switch mechanism), and my suspicion is that if these bearings were lubricated, and the grease or oil became sticky, the balls won't move and no interposer can go fully in.

    Also, the typewriter has its carriage return mechanism stuck in the engaged position, pulling the carriage all the way to the left not disengaging after it's done. One of the levers is in the upper position and after I put some force on it to make it go down, the carriage is left in peace.

    Anyway, it's mostly just taking deep dives into the service documentation, analyzing the mechanism schematics and operational principles, hypothesizing about causes of problems and testing these hypotheses. Makes me wonder if anyone in the hacker community had as complex a restoration as I'm having now.

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durk van der Ploeg wrote 01/02/2023 at 20:47 point

nice project.

I just completed restoration of a lorenz lo15 telex machine, and controlled it via an arduino to print ASCII art.

necxt project is a IBM selectric I.

First problem to tackle was to get a UNC 6-32 left threaded bolt as tool to turn the function shaft manual for adjustments. Really hard to get in Europe....

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Isaac Wingfield wrote 12/20/2022 at 04:50 point

Rebuilt one of those back in the late 70's to use as a printer with my CP/M box. Probably the most elegant mechanical device ever built. Built an ASCII-to-tilt level-rotate translator to drive it. Had full feedback so it wouldn't stop between successive characters (different characters took different amounts of time, unlike a teletype). Used it to pretty-print resumes for several years.

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Keri Szafir wrote 12/20/2022 at 10:28 point

Nice! I wonder how you did that one. Did you actuate the selector interposers with a bunch of solenoids, with some additional ones for space, carriage return/line feed etc.?

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Isaac Wingfield wrote 12/22/2022 at 05:23 point

Exactly. Solenoids for 1, 2, 5(??) IIRC. Set 'em up and release the clutch (didn't have to add those because this was already a computer printer). The thing had been an airline reservation printer, and was so worn that there was no plating on the ball's letters, and the platen was just rows of craters. Bought replacements from the IBM repair center in LA for an amazingly low price. The translator was a simple state machine and a ROM where an address was the ASCII code and the output was the tilt-rotate.

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Dan Maloney wrote 12/19/2022 at 23:00 point

Oh yeah, the typewriter geek's ultimate tool! The pinnacle of typing technology -- how could you not love anything that has something called a "whiffletree" in it?

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Keri Szafir wrote 12/20/2022 at 10:26 point

Whiffletree, not whoofletree :D
It's interesting that this mechanism has been around for ages and comes from the world of agriculture, with carts and machines pulled by animals. Real deal horse power!

While the selection mechanism itself works like a charm, it's the keyboard that didn't work. It turned out that a bunch of latches and interposers were out of tune, this machine definitely needs some love but it's getting there.

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Ken Yap wrote 12/16/2022 at 23:11 point

Wow that's a piece of history there. That Selectric III is lucky to have you. Looking forward to the tale and the result; hope that's not too much pressure. 😀

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Keri Szafir wrote 12/17/2022 at 00:48 point

Will do. That's a thing of beauty for sure, I definitely want to fix it.

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