[GreenKeys] Cleaners, lubricants, pipe-dream "The way things work" animation

[John Lawson]

On Sun, 20 Jul 2003, Tim McNerney wrote:

[snip]

>
> On the topic of figuring out how Model 28s and 35s work mechanically by
> staring at them and studying the manuals...
>
> ...sure I wish I could get David Macaulay, author of "Underground",
> "Cathedral", and "The New Way Things Work" to team up again with the PBS
> animators who produced "Mill Times" to build us a working "virtual" model of
> a teletype.  Once you had such a beast, you could, for example, "get inside"
> the selector mechanism while it's running to see how the solenoid and cams
> conspire to set of the code bars.

  I got my first Model 14 (a 1/4" gummed paper tape machine, complete with
the WU Telegram attachment) when I was as old as it's model number.  I
paid $40 for it - a whopping lot of money for a 9th grader in '66! I built
a TU out of QST using 6SN7s and two precious toroid 'heat coils' given to
me by an Elmer.  The machine was old and gummy, so one fine day I just
took it all apart.  It took a week of near-constant effort to get it back
together - working with no manuals and simple tools and just a good
mechanical 'intuition' - but, after some dead-ends and fiddling around, it
finally worked. I *never* had the cover back on itafter that - I loved to
watch all that Stuff cranking away, and of course the noise, and the smell
of warm motor and light oil...


   [pause while the writer goes out and fires up the Mod 19 for a bit...]


   Where was I - oh yeah.  Later that summer I found a ratty old General
Radio Strobotach at a hamfest. My electronics teacher had shown us one of
these - and the first thing I did with it was to darken the room, set the
machine printing AP, and use the strobe to 'freeze' the mechanism.  I was
so fascinated that I kinda forgot it was just an optical illusion, and
tried to lift one of the code levers, and of course got my pinkie mashed
good for being stupid...  ;}

  So if you can score a decent Strobotach used (they are in the $50 to
$100 range at most hamfests and flea markets) you can use it to observe
the workings of the machine...  by adjusting the frequency of the flashes
you can see it in slo-mo, and also 'freeze' the various portions that run
at different speeds.

  I like to set a continuous RY loop in the reader and then set the Strobe
at just a bit over speed...  your ears are telling you that it is typing
normally, but your eyes see the type-bars lifting s-l-o-w-l-y up and just
touching the paper, while the mainshaft drifts lazily around...  quite a
show.


>
> My motivation, BTW, is to make computers more accessible to children by
> using "digital machines" as examples.  For many students, digital
> electronics are too abstract.  There's nothing geometric, no physical
> cause-and-effect to "wrap your head around" inside a modern computer.  Now
> old Teletypes, on the other hand...


  I would reccomend that you consider subscribing to the Classic Computers
mailing list (www.classiccmp.org). There is quite a bit of membership
overlap between here and there [I also collect DEC PDP-11 minicomputers]
and you will find several folks who have the old mechanical 'toy brains' -
like the old Geniac, and the plastic Digicomp, that does all the functions
of a Von Neumann machine using levers and rods.  One person I know has
taken molds from his example and is planng on re-issuing it as a kit. But
many folks there collect the 'instructional' type devices, so you would
surely find things to help you in your endeavors.

  I had a complete IMSAI 8080 system for quite some time, and when I was
teaching Ham Radio classes, I'd take the covers off everything, boot up
CP/M, and the do a bulk file copy from one 8" disk to the other - and let
the kids crowd around and watch the lights on the front panel dancing, and
the heads moving over the spinning disks - it certainly gave them a bit of
perspective on computing as a hobby.

  Of course they *really* liked the big Tesla coil, but thats a bit
off-topic...



>
> Incidentally, it has been documented that kids who learn how to maintain
> motor-scooters have an easier time learning about computers (see
> "Technological Fluency and the Art of Motorcycle Maintenance" by David
> Cavallo: http://web.media.mit.edu/~cavallo/Thesis-index.pdf).
>

  A lot of kids have no opportunity in what's left of our 'schools' to
have shop classes (or music, or art for that matter) so they grow up with
"Don't touch that!" drummed into thier heads.  Another thing I'd do at the
Ham classes was to bring junk from the swapmeets - old dead gear and radio
stuff, and I'd let the kids take it apart. You put a screwdriver and a
pair of dikes in a boy's hand and let him work on things, (read: rip old
stuff up) and he'll soon get the idea that he *can* do this...  coupled
with the general electronic knowledge that working toward a Ham License
confers -

  You plant the seeds - no telling where the trees will grow.  I've had
more than one person in my classes tell me that they went on to get
engineering degrees because of their exposure to Ham radio and general
electronics in my (and others') classes.

  And we need more hardware geeks to keep collecting and maintaining
Teletypers - no?  You betcha!

  Cheers

John KB6SCO