In uk.d-i-y, Can2002 can2002@nospammaildotnet wrote:
We've just moved into a house that was converted from a bungalow a few years
back; all the interior walls upstairs are plasterboard. I want to install a
DAB aerial on the roof and ideally run the cable through the loft and down
through the gap between the wall by our study. My draft action plan is:

Install aerial and run cable up to just above my study (need to find some
method of measuring distances to ensure I'm in the right place)
Drill a hole through to the cavity
Drop cable down into cavity
Drill hole through wall in study and attempt to locate cable
Install wall mounted coax point

Achievable - certainly; fiddly - also certainly. The long "wot I did in
the last few days before getting back to work" screed I posted earlier
today - "Adventures in Loft Land" or some such title - describes recent
cable-fishing experience in gory detail. Those were all *internal* stud
walls, i.e. plasterboard both sides; I'm assuming you have the same (since
if it was an external wall you'd just come right through from outside,
right?).

In which case: when you go up in the loft you'll probably be able to
work out quite quickly from stable reference points - e.g. overflow
pipes, end walls, etc. - roughly where the internal wall is. I find it
a Good Idea to confirm the guess with a small hole drilled up through
the edge of the ceiling - your smallest masonry bit at 4mm is plenty,
or poke up with a bradawl - then feed a stiff bit of wire or similar
(hell, bamboo BBQ skewer will do, you won't be using them in this weather
;-) up through it and see just where it pokes up. You can fill this hole
with a dabette of Polyfilla or similar Later.

Now you know more certainly where the internal wall lies from the top.
This is a good moment to cut the hole for the back box of your coax point
where you want it; at "standard" wallbox size, about 7cm square, it's big
enough to poke in fingers, and a tape measure to get a good idea of the depth
of the cavity (tells you how far along from your trial hole to drill your
down-hole). Plasterboard is easy enough to saw with a full-size hacksaw blade
held in the gloved hand, or a sawblade you can get for Stanley knives, or
similar: you certainly don't "need" a Rotozip cutter (though if your heart
is set on one, far be it from me to stand between you and your tool-lust ;-)
If you have a mirror narrow enough, you can now look up the cavity, shining
a torch into it from a position close to your eye to carry the reflected
light where you're looking. If the gods of d-i-y want to trip you up on a
different part of the job, you'll find no noggins in the way. (If there
are, you'll have to cut out little bits of pboard above each one, drill
through at an angle, and then fill the hole, e.g. by gluing scrap bits of
pboard or similar to the back of the neat piece you cut out, using glue/filler
on the front side of those wings, and pulling it up against the inside
surface of the pboard with a screw you put in the main bit of pboard, or
a bit of string/wire looped through it; then fill the screwhole and edges
when the glue/filler has set).

Now hie thee back into the loft; drill that hole in the pboard above the
cavity, within a couple of inches horizontally-speaking of the exit hole
you cut below, to increase your chances of fishing out the dropped cable.
Drop in either the DAB downlead itself, or a handy-dandy bit of spare cable;
something relatively heavy and neither very stiff nor utterly floppy is
best. Attach a weight to the end if you like; I don't bother. It's useful
to mark the vertical distance down to the exit hole on this dropped cable:
then you know you've dropped enough (in practice drop at least a foot more,
to allow for some gentle bending on the way down).

Now comes the fun bit: finding it in the cavity near to the exit hole.
Working with an Assistant can help - one to drop, the other to watch and
listen as it bumps and rattles its way down. But if you're working on your
own, it's not too bad. You may be able to see the dropped cable near the
exit hole (a white jacket shows up better in the gloom!); or you may be
able to feel it if you're very lucky; or you may find an improvised hook
at the end of a bit of wire coat-hanger brings you the dropped cable -
worked for me on the very first attempt on one of this weekend's drops. Or
you can try the uk.d-i-y Tape Measure Trick, which has worked for me in
the past: feed a big loop of steel measuring tape, or the package-strapping
which comes round your Screwfix parcels (favoured access tool of the
car-nicking scrote), horizontally into the cavity, *before* you drop the
Expeditionary cable. The aim is to get it to form a loop around the edges
of the cavity. Now drop the cable, and pull the loop back out: with luck
it'll bring the dropped cable with it.

At this point, with the dropped cable pulled through, relax with a beer,
tea, or similar. Sod & Murphy will get you later anyway - e.g. making
sure you cut the DAB downlead 50cm too short anyway, or by having your
draw-wire part company from the DAB downlead even though you taped them
together good&proper, or by arranging a lightning strike to take out
aerial, downlead, and that nice new DAB tuner a week after you've put
it in. So take your pleasures when you may...

Hope this helps - Stefek