26 Aug
2007
26 Aug
'07
11:25 p.m.
From: "Chuck Guzis":
On 26 Aug 2007 at 21:10, Vincent Slyngstad wrote:
Sort of, but a couple of the magic bits would be lost that way.
Fashioning the pivots, at the rotational center of the things, would
require additional work. In addition, the parts you hit with your
fingers aren't square -- they are tapered, so there is actually
space between the tips, but not between the bases:
\ /
=
(but not so pronounced). That turns out to be an important part
of the user interface, making it easier to hit just the switch
you want.
Here's a nice side view of one of the ones
for some of the PDP-8's.
There is also a long rocker style, and a sort of triangular style
that was used on some of the PDP-11's.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290149624244
Ah, many thanks--now I understand. Would it be possible to mill out
the profile in a big hunk of polycarbonate and then slice the paddles
off like slices of bread? The result could then be painted. I wonder if you could cast some out of zinc-aluminum
alloy using a
lost-wax process? Metal ones would be more durable.
I think that would work, but it sounds like more work that the
silicone molds and plastic resins. Durability isn't much of a
problem, except with the pivot pins. (The pivots can easily be
drilled out and replaced with a length from a large paper clip,
when they break off.)
The URLs I gave earlier for the replacement Straight-8 paddles
had some nice pictures, which would illustrate the taper and
show one with the pivot pins replaced with a metal axle.
Vince
(Do not attempt to cut a paper clip with your favorite diagonal
cutters, as the metal is often tougher than the cutters, and will
deform the cutting surfaces.)