[GreenKeys] Mod 33 keyboard repair and disassembly

[Jones, Douglas W]

With reference to:
-- http://homepage.cs.uiowa.edu/~jones/pdp8/UI-8/log.shtml#2015-01-22

The Teletype Model 33 ASR I am restoring has a keyboard cover
(part number 180027, I think) with 6 broken-off mounting lugs
on the ends -- 3 on each end.

It is easy to conclude that the lugs were 3/16" diameter, and
that the middle lug on each end had provisions for a C-clips
(part number 119652).  We have one such c-clip salvaged from
the debris found in the sub-base, but I think it will be ignored.

My question:  How long were the lugs that broke off?

Note that the Teletype obviously worked for a long time with
these lugs broken off -- the keyboard cover has shallow grooves
worn into its base where it rested on metalwork below while being
pounded on by typists.  Nonetheless, repair or replacement seem
to be in order; I've opted to repair (and I have new keycaps on
order, so I'll be disassembling the keyboard quite a bit more --
hints about this are welcome, since it looks a bit daunting).

I have opted to replace them with 10-32 screws, drilling and
tapping the plastic where each lug broke off.  2 screws will be
screwed into each end from the inside sticking out, and one
screw will be screwed into the center hole at each end going
inward -- so the screw can be turned to have the same effect as
the missing C-clip.  I've verified the clearances, but I need
to know how long to cut the outward facing screws.

A steel 10-32 screw threaded into the plastic from which the
lug broke off ought to be as strong as the plastic lug, but
the center screws that someone could overtighten will be backed
up by steel nuts on the inside of the keyboard.

		Doug Jones
		jones at cs.uiowa.edu