Keyboard actuator

From: Dwight Elvey <elvey_at_hal.com>
Date: Thu May 11 19:50:38 2000

ard_at_p850ug1.demon.co.uk (Tony Duell) wrote:
> >
> >
> > I have to jump in since someone brought up the Selectric.
> >
> > Has any-one here ever dismantled a Selectric? Did once
>
> Never done a Selectric. Worked on teleprinters, though, and some of those
> have some _strange_ mechanisms. Olivetti had a binary->position decoder
> that consists of a series of metal cylinders each with an eccentric hole
> such that each one fitted over the next smaller. These were rotated into
> one of 2 positions according to the state of a particular bit (one bit
> for each cylinder, all cylinders could move separately), so the
> overall displacement of a follower on the largest cylinder was determined
> by the total binary value of all the bits.
>
> Creed made a paper tape reader where the holes in the tape for a
> particular characeter were sampled one at a time by a series of metal
> 'peckers' and the state transmitted serially by a single contact assembly
> operated by a link from the peckers.
>
> Creed also had an amazing carriage feed mechanism consisting of a pair of
> pawls opeated by a camshaft (half a turn per character IIRC) that 'walk'
> along a rack fixed to the carriage. That one is almost amusing to watch.
>
> > and though I thought knew mechanisms at the time it turns
> > out I sure didn't. The central mechanism seemed like a cross
> > between Dr. Nim (On Topic) and DigiComp-1.
> > The key presses were relayed by an almost binary series of
> > pushrods to a cascaded teeter-totter matrix.
>
> FWIW, I believe the service manuals for Selectrics were available from
> IBM, and maybe they still are.
>
> > The damndest mechanism I've ever seen. Anybody else have
> > this reaction?
> > Seems like a pretty good topic so I'm chiming in with this...
> >
> > John A.
> > P.S. Don't go breaking up working ones to find out though.
>
> Dismantling a machine is not equivalent to breaking it up :-). It can't
> be that hard to get them back together again...
>
> -tony
>
> >
>
>
>
Received on Thu May 11 2000 - 19:50:38 BST