15 Jul
2009
15 Jul
'09
11:11 a.m.
From: "Ethan Dicks" <ethan.dicks at gmail.com>
Sent: Tuesday, July 14, 2009 2:56 PM
I have tried that, and did notice some fatigue of the sockets. Since the
sockets looked even harder to repair that the bulbs, I quit using that
technique.
Vince
On Tue, Jul 14, 2009 at 5:19 PM, Steve
Maddison<steve at cosam.org> wrote:
> I think we're talking about these little <insert expletive here>s:
>
> http://www.cosam.org/images/pdp11-35/filler_bracket.jpg
I have cast those with pretty good success. The way that seemed to work
best was to cast the RTV mold with the thing laying as pictured. Then when
the RTV sets up, flip it over, and remove the original, exposing the whole
whole back. Then fill with the 2-part plastic resin, being careful not to
leave air bubbles in the recesses that will form the bulbs. I also like to
fill it slightly over-full, so that the back is bulgy, then sand the face
that
bolts to the rack nice and flat. I run the part over a block of MDF with
half-sheet of sandpaper, as the MDF has the nice flat surface I want to
end up with on the back of the new part. (Sanding may expose bubbles
inside the part, they shouldn't be large enough to compromise the part
so you can ignore them.)
The bulbs will fatigue the mold as parts are removed, so each mold is
probably only good for 6 or 8 good castings.
It can take a
bit of leg work, but if you're lucky you can find
self-tapping screws with nice rounded heads which fit in the holes on
the panels. Just trim/file the stump flush with the bracket, drill out
a pilot hole and screw in said self-tappers a few turns. These
replacement ball joints are much sturdier than the originals!
Hmm... I haven't ever tried that, but I can see how it could work. I
might be concerned about metal-to-plastic wear on the cover panels
from repeated reconfiguration, though.