Questions, Answers & Tips -
Electrically, the size of the gap isn’t important as long as current
can’t cross the gap. In terms of looks and operation, a large air
gap is unsightly and can cause tracking problems.
Once you are skilled with the cut-off disk, you can cut the
gap with a series of light passes which will not melt the plastic
ties of commercial turnouts. Melting lets the tiny molded spike
heads lose their grip, which will eventually lead to problems.
An alternative is to make the frog and closure rails as separate
items, then fix them down with as close a gap as you wish, but
this requires care and precision in alignment.
While it seems like a gap would stay in place after it is cut,
that is not always the case. Flex track can expand and contract
inside its plastic base. Copper cladding or solder joints on PC
ties can let go. Humidity and temperature changes can cause
benchwork to move.
Filling the gap avoids exposed rail ends which may provoke
wheels to “pick the edge” and climb up and over the railhead.
Filling the gap immediately and completely eliminates the pos-
sibility of the joint creeping or closing up, which can cause pos-
sibly the most infuriating impossible-to-diagnose “but the layout
worked perfectly yesterday” short circuit.
Gaps can be filled with bits of cardboard (think recipe file cards),
styrene, or any of several liquids. Once the gap-filler is slid into
place, glue it with CA and trim the filler to fit.
Liquid gap fillers
:
Bruce Petrarca likes Faller Expert cement, available from
Walthers, which is methyl chloride with styrene in the mix.
Squirt a bit of it into the crack with the included needle nose,
reapply if needed, and lightly sand to shape with 600-grit sand-
paper or a fine emery board.
MRH-May 2014
