In article , Ian Malcolm
wrote:
whit3rd wrote in news:9509c6e6-b466-489d-8982-
:
On Tuesday, December 8, 2015 at 6:28:11 AM UTC-8, Joe Gwinn wrote:
Yesterday, I noticed that the lamp hanging over the kitchen sink was
no
longer hanging by the woven polyester cable sheath (which is intended
to carry the weight of the lamp fixture) and was now hanging by the
electrical wires. Which were coming undone -
So, I replaced the metal ferrule with a double constrictor knot made
of
nylon cord, all well daubed with Pliobond rubber cement.
Sounds good, and it's likely the rubber cement won't attack the
materials. I'd have used hotmelt glue, and instead of a knot, just
a wrap or two of a nylon tie-wrap. Anything you can get tight, that
stays tight, should work at least as well as the original did.
Its a kitchen, so unless you never eat fried or baked food, the chances
are the insulation and cable jacket was contaminated with condensed food
oils and greases.
A constrictor knot only works if its done in cord of an appropriate
thickness on a clean rounded surface, and it *MUST* be pulled up tight.
If the knot isn't pulled tight or the cord is too thin (or surface too
flat) so there isn't enough pressure on the crossover or the surface is
too curved so the ends are free to shift it will fail. Also Nylon is
particularily slippery. To have stood a good chance of it working, you
would have had to degrease the cable jacket, and use cotton or hemp
cordage, or unwaxed polyester then locked it with a drop of superglue.
All those things were done, except for the crazy glue. The reason for
pliobond is that it is solvent-based, and quite tolerant of oils.
What I think happened is that the heat softened the insulation on the
wires, causing loss of clamping pressure, and increasing creep.
As-is: clean the jacket with hot water and detergent. Dry and wipe with
alcohol. Reinforce with a short length of adhesive lined heatshrink,
taking care NOT to overheat the jacket while shrinking it then use a
nylon cable tie looped round twice and pulled tight with pliers.
The heat shrink could work, but I think I'm going with a metal clamp.
I did some google research, and the best cord camp is a thick-walled
metal tube with a perpendicular round-face set screw. This is a
standard design.
Joe Gwinn