Todays Topic from Panelman

rod rodsmallwood52 at
Tue Nov 17 02:34:52 CST 2015

Hi Guys
             I think we are all only too well aware of the difficulty of 
getting parts for our old systems.
This the more so for items that can been seen.
Having got at least a half reasonable replacement front panel process my 
thoughts turned to toggle switches.
In the case of PDP-11 this is already being addressed by another list 

So to PDP-8's. There's two parts to a PDP-8 toggle. The slide switch and 
the lever.
The leaver is injection molded in a two part mold. The join line can 
clearly be seen.

Clearly a mold is required to produce one or more at a time.
These used to be very expensive but with modern CNC machines it might be 
worth finding out.
In addition we now have 3D printing available
To aid this have I have produced a drawing of the switch lever with 
views from three angles.

 From here it should be possible to:

                 1. Convert to 3D for 3D printing tests

                 2.  Produce a drawing of the two part mold tool.
                      Extruded PVC I'm familiar with having worked in 
the cable industry as a student.
                      ABS which is what I think the leaver may be made 
of may be different (hot to cold shrinkage for example)

Comments from list members with experience in the above areas would be 
of interest to us all.

Now to the slide switches themselves.

They are mounted by the screw hole lugs having been slid into  a groove  
in two aluminum bars which in turn are attached to the PCB by pillars 
and screws.
There are six connection pins on the bottom of each switch that go into 
holes in the PCB. (not all used) Switch replacement would be easy and a 
complete switch and lever sub module not too difficult. I hear a voice 
from the distant past saying 'Micro switches'

Thats all for to-day


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