I knew from the start that I wanted my wife to be able to hit
Enter by slapping the carriage return, so as to reproduce as closely as
possible the feeling of actually typing on a typewriter (which you can
still do on this thing, by the way- it is still fully functional as a
typewriter). Took me forever to figure out how to do it, and even then
I kind of cheated.
What I finally settled on is a mechanism on the carriage itself
that is responsible for dinging a bell when the typist reaches the end
of a line. There is a small "hammer" that is pulled right (in this
illustration) across the "anvil" when the end of a line is reached (I
don't know what the hell these things are really called, so I'm just
making these terms up). The anvil strikes the bell, shown through the
hole in the lower left. After this is done and the end of the line is
reached, the carriage comes to rest as shown in the illustration. When
the carriage return is slapped, the hammer moves gently across the
anvil, going in the other direction (the hammer is on a spring, so it can pivot counterclockwise around the screw shown).
I wrapped the anvil in gaffer's tape and lamè and soldered a wire
to it. The trouble was the hammer. I finally gave up on attaching a
wire to it, as it would be almost impossible to keep it from getting
jammed in the carriage, which would be moving back and forth all the
time. So I cheated- the circuit for Enter is dependant not on two
pieces of lamè touching, but on one bit of lamè touching
the metal frame itself, in ths case the bare hammer. I figured it would
be OK: since every other wire had to be insulated from the frame anyway, it
would be no more likely to cause an error than any two regular key
circuits accidentally touching the frame.
After wraping the backside of the hammer in gaffer's tape so it
wouldn't close the circuit when it rang the bell (which still works),
all I had to do was solder a bit of wire to the frame and I was set. In
case there was ever any trouble with this perhaps precarious mechanism,
I also wired the ¢ key on the typewriter to act as a backup
Enter.
Space
The spacebar was pretty simple, as there was a spot underneath where it
struck a rubber pad. All I had to do was make the usual gaffer's
tape-lamè-wire contacts and it was ready.
Shift
Shift was a bit tricky. That is, it was easy to plan but because of the
tight space and awkward angles it took a bit of doing to execute.
Basically it was the same sort of contact, but this time wrapped around
the bar that the "Shift Lock" mechanism locks on to. Unfortunately, I
had to wrap the locking mechanism in gaffer's tape to prevent a circuit
from forming with the frame, and this made it unable to actually lock
the shift mechanism around the bar (wrapped in gaf tape and
lamé).
My only real regret on this project is that I never found a way to make
the Backspace key work, since the mechanism that controls it is deep
inside the typewriter, far to deep to get to without risking disaster.
Next: putting it all together.
erik@SPAM-ME-NOT.multipledigression.com (minus the spam filter)