Re: Is soldering a absolute must?

"Daniel A. Mitchell" wrote:
> 
> No. It is not even a good idea to solder ALL your rail joints. Some
> 'give' for expansion and contraction is usually needed somewhere.
> Likewise don't lay the rail solidly butted together at the joints ...
> leave a small gap. It's not so much the rail that changes dimension, as
> it is the benchwork. Layouts swell in humid times, and shrink when it's
> dry. This usually follows the heating/air conditioning seasons, and
> depends on your climate.
> 
> In general NEVER rely on an unsoldered trail joint for electrical
> contact. They may work well for a while, even a few years, but dirt and
> corrosion will eventually cause the metal-to-metal contact to fail.
> Also, minimize the number of rail joints by using 3' sections of rail or
> flex-track. DON'T build a large permanent layout with short sectional
> track. Every rail joint is both a potential electrical problem and a
> potential point of derailment.
> 
> There are two systems that seem to work best, from my experience.
> 
> 1) Solder the rail into lengths about ten feet long, and provide a
> feeder wire to each rail section.
> 
> 2) Solder a feeder wire to EVERY rail section, and don't solder any of
> the primary rail joints. ... this is a bit more work, but is probably
> the best solution overall.
> 
> Of course, some combination of the two can also be used. Some
> modification is almost always necessary to suit particular situations.
> Normal electrical 'block' lengths may provide a satisfactory length for
> continuous soldered rail. You'll find situations where you may want to
> solder SOME rail joints, especially where several short sections are
> connected together, as can occur around switchwork. This assists with
> mechanical stability as well as electrical contact.
> 
> Dan Mitchell
> ==========

I agree with this.  Expansion and shrinkage of the wooden benchwork from
dry heating season to moist summer can make the roadbed grow or shrink
by large factions of an inch over a room length table.  I lay the track
with a bit of clearance perhaps 1/16th inch, between each rail.  Good
tight new rail joiners will hold the track in mechanical alignment and
permit a bit of "give" down the length of the track.
  To get juice to all sections of track after a rail joiner gets some
corrosion under it and stops conducting, I run a power bus wire under
the table all around the layout.  Use good thick wire.  Number 14 solid
house wire is readily available at Home Depot.  Then solder thin feeders
up from the under table bus to the track.  Ideally each piece of track
gets it's own feeder.  In practice things work OK with fewer feeders. 
Solder the feeder wires to the track.  Use Radio shack alligator clips
as heat sinks to avoid melting ties.

David Starr