piano wire. The wire is
then bent back under-
neath the shim and
held in place with small
screws. The screws add
additional weight to
the shim.
With the wire attached
to the shim, it’s then
positioned underneath
the layout. I found that
it’s important to make
sure the wire slides
freely through the brass
sleeve. If it binds, the
wire won’t drop down
when released. Make
sure that the wire and
shim combo are per-
pendicular to the sleeve
and roadbed when
installing them.
Fighting Gravity
The wire was now
free to drop into the
unlocked position, but I
needed a way to prevent it from dropping down to the floor. I
only needed the wire to drop enough to clear the throwbar, a
distance of less than an inch.
First, I needed a way to attach the shim and wire combo to the
underside of the layout, but still allow it to move freely. Luckily,
I use extruded foam as my sub-roadbed. Some short but thick
roofing nails give me the leverage I need to act as a hinge on
Locking up your layout - 6
the same diameter as the wire to allow it to fit snugly when
locked, then trimmed the wire flush with the top of the throw-
bar. To stiffen the wire and make sure it wouldn’t wiggle loose
in my extruded foam sub-roadbed, I use a brass tube as a
sleeve around the wire. The tube also reduces friction as the
wire moves through the roadbed.
With the wire in
place, I needed
a way to lift and
remove the wire to
lock and unlock the
turnout. I decided
I wanted the wire
to default to the
down, or unlocked,
position. That
way if there was
a mechanical fail-
ure, I could easily
unlock the turnout
without affecting
its operation. By
itself, the wire is
not heavy enough
to drop down on
its own. I devised
a way to use a sim-
ple wooden shim
to add additional
weight to the wire.
A hole is drilled
through the thicker
end of the shim to
feed through the
10
10: Stiff but thin piano wire
is then threaded through the
throwbar hole and into the sub-
roadbed. James uses extruded
foam so he doesn’t have to drill
through a plywood base to pass
the wire through.
11
11: The wire is threaded
through a brass tube to stiffen
it in the sub-roadbed and
prevent it from moving around
in the foam.
MRH-Dec 2013
