[TR] Horn with a mind of its own

[Randall]

> Randall, what size gun did you use?  I've always had a hard 
> time heating a big surface with a gun enough to solder a wire to it.  

I believe it was rated at 140 or 150 watts.  Unfortunately, it seems I've
managed to lose it after all these years, so I bought a new one the other
day (only gun they had, rated 200 watts).

But the copper face of the stock gasket is pretty thin, and you only need to
get a small area hot enough to melt solder.  It didn't seem to be a problem
at all.

Clean the surface thoroughly first, of course.  I used Tarn-X this time,
which seems to work fine.  Last time, I scrubbed with a Scotch-Brite pad and
then smeared the area with soldering flux; which also worked fine.

Here's a photo:
http://goo.gl/WRV2C

I'll mention these items just because someone else said they didn't know:

1) The tip of the gun should be in good condition, with large flat area to
contact the head gasket and a clean bright layer of solder (aka tinning).
If it is pitted or blackened, dress it back to shape with a file and then
re-tin with solder.  Mine tend to erode into a U-shape over time that
doesn't transfer heat well.  If there isn't enough metal left to dress to
shape, buy a new tip (they're only a few dollars).

2) Avoid lead-free solder if you can.  It's much harder to work with, IMO.
Rosin-core "eutectic" (aka 63/37) is the hot setup (though it's more
expensive than solid core plumbing solder).  Kester is my favorite brand,
but Alpha is good, too.

3) Weller guns (only kind I know) have a pair of nuts or setscrews that hold
the tip to the gun.  It's worthwhile to occasionally loosen and retighten
those, as the copper tip tends to develop a layer of corrosion that will
impede current flow (and hence reduce heat).

-- Randall