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Planning and laying track
General hints
By the time it comes to laying track, you should have a good idea of the route
it will follow, either as a detailed drawing or just as a vision in
your mind. In either case, it's time to fasten the track to the baseboard.
If you are using pre-cut pieces, you can't really go wrong here, provided
that some simple rules are followed. If you are using flexible track
you need to be more careful. Suggestions follow.
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Whether you are using pre-cut or flexible track, adjacent sections
must meet perfectly with no kinks or sudden changes of direction.
The second-best way to ensure this is to
sight along the track. It should be fairly clear if there are any problems.
The best way is to run your longest, most troublesome train over the
joint at the highest speed you will ever use. Then do it backwards.
If it can do this ten times in each direction, and not even wobble,
it's probably OK.
It's easy to underestimate the significance of this
problem. I have, for instance, a Hornby steam locomotive
with a six-wheel tender, that
ran perfectly well most of the time, but occasionally would just stop
at a random place with its wheels spinning. Eventually
it turned out that the middle pair of wheels -- which have
no flanges and can move slightly side-to-side -- were being deflected
to the side and jamming against the inside of the track.
The problem was traced to
a small kink in a curve where two tracks joined; on passing this
kink it pushed the middle axle of the tender into its fully-sideways
position, where it stayed for a while until one of the wheels dropped
down and jammed on the track. The defect was hardly visible to the
naked eye, and the problem did not even manifest itself at the
point of the defect.
You will find as construction progresses that you need to repeat this
test on sections of track that get moved by pulling on them. You really
don't want to be pulling up track once a load of scenery and buildings
are in place, so it's worth being really thorough here.
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When using flexible track, it is easy to find gaps developing
between adjacent track sections as you work.
My approach to this problem is to
pull the track through its sleepers with pliers, so that every
track end is butted firmly up against its neighbour. Otherwise
these gaps will create problems, both electrical and mechanical.
A gap of a half-millimetre or so is not a problem, and may be advantageous
to allow for expansion. With pre-cut track there should never
be a gap of more than half a millimetre if you have assembled it
properly (and it is manufactured properly).
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When joining track with fishplates, it is easy for the fishplates to
fail to engage properly, so that one track end is elevated a millimetre
or so above the other. Be careful: this is enough to derail a coach.
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Ideally you will have drawn all your curves out on the baseboard before
laying any track. A piece of string, a ruler, a pen, and a pin are enough to
draw a perfect curve of any radius. At the `experimental' stage you can
get a rough idea of the radius of curve that will fit into a particular area by
comparing it to the size of circle that would be made by joining flexible
track sections. If your flexible track is in 3-foot lengths (it usually
is), then a circle made of four sections of this track would have a radius of
23". Another way of looking at this is if you bend a 3-foot length around a
right angle, that gives a bend radius of 23" (provided it's smooth).
A 23'' radius will accomodate must locomotives and trains. It's a bigger
radius than most proprietary pre-cut track systems provide. A
circle made of 3 pieces of 3-foot track will have a radius of 17".
This is probably as small as you want to go, if you run full-sized
tains. This corresponds to making a third of a full turn with a
3-foot section.
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Track cannot be layed robustly by relying on the fishplate joints
between the sections. It needs to be pinned to the baseboard.
You can get short pins from model shops; ordinary half-inch
tin tacks may not be useful here, as they are too thick. Pre-cut
track sections usually have holes drilled in strategic places for
pins. Flexible track usually doesn't: you will need to push the
pins through the sleepers and into the baseboard. I find it helpful
to hold the pin shank in the jaws of a side cutter, and then push the
body of the cutter down and the pin with it.
Working with flexible track
I have already discussed the advantages of working with flexible track:
it is cheaper, can follow any curve, and can be cut to any length.
However, it does take some practice to work with this stuff, and it's
easy to get into a mess.
The first problem you are likely to encounter is cutting the track. Various
possibilities suggest themselves: pliers, hacksaw, bolt cropper,
etc. A hacksaw produces
a smooth cut surface, but it's tiresome when you have hundreds of cuts to
make. Moreover, it's fiddly to keep both rails still while cutting
(someone makes a jig for this, which might help). I use a stout pair
of side cutters, which cut cleanly but leave a slight burr. Although
slight, this burr is large enough to stop the fishplates fitting
properly, which is bad. You can file the burr off or, as I do, simply trim
the burred area with a smaller cutter. Be warned that even a slight
distortion of the cut end will result in the track segments not
butting correctly, which will cause problems when running trains
later. Another popular method of cutting, which I have not tried, is
to use a miniature high speed disc cutter (Dremel make one). This, I
am told, cuts quickly and without burring.
The next problem to overcome is to ensure that the joined track
segments make perfect, smooth joins (as described above).
I find the best way is to pin the sleepers on each side of the join
as soon as possible, then add pins working away from the join. I suggest
testing each section with a train as soon as it is connected.
Don't forget that with flexible track, there's no guarantee that the
lengths provided will allow points, etc., to lie in the correct
places with respect to one another. Where you have points that
work together (e.g., `slips' between parallel tracks) you'll need
to mount the points first, then join them with track.
Ballasting
Real track is secured by a heavy layer of gravel ballast. This
lies between the sleepers and reduces the tendecy of the
track to move when trains pass over it. You can get this effect
in a model railway using fine crushed gravel, avaliable from
model shops. To simulate sandy areas you can use... er... sand.
There are various well-established techniques for sticking the
ballast to the trackbed. One method, which I confess I
have not found very
effective, is to drip glue onto the area to be ballasted, and
then sprinkle the ballast. The problem with this technique is
that if you don't get perfectly even coverage first time,
it's difficult to adjust, because the glue prevents the
ballast being smoothed out. The approach I favour is too
poor the ballast all over the required area, smooth it
with a small brush, and then poor thinned glue over
the top. Hint: about three parts water to one part glue,
with a few drops of detergent. The detergent reduces the
water surface tension, so the mixture can flow into all
the gaps. The photos below show a section of track
before and after ballasting. In the `after' photo
the glue is still partly wet.
Wiring
If you aren't planning to use DCC for controlling your
trains, you will need to take the wiring requirements into
account when planning and laying track. Remember that
traditional DC control systems work by controlling the track,
not the trains. If you have points controlling access to
separate sections of track, the normal rule is to apply
power to the `feed' end of the points (that's the end that
both tracks run to) only. This allows the position of the points
to control which track section is live. Beyond this I haven't
much to say on the topic: wiring track for DC control is
a specialist skill that I haven't had to learn. With
DCC control, we simply wire all the track together. The only
caveat is to ensure that all the `right hand' rails in the
layout are connected to all the other `right hand' rails,
and all the `left hands' to the other `left hands'. Otherwise
there will be a short circuit across the power unit.
There is one place where this strategy won't work, and that's
in a `reversing loop' arrangement. This is one that looks
like this:
/-----\
---/ \
\ /
\-----/
and allows a train to enter it and come out facing the other
way. If you think about the wiring, the left track on the
entry to the loop joins up with the right track on exit,
and vice versa. It's an inevitable short circuit.
There is an (ugly) way to deal with this in traditional wiring,
involve two-way reversing switches. With DCC it goes against
the spirit of digital control to use manual switches; happily
you can get a gadget that takes care of it automatically.
The procedure is to isolate both limbs of the loop from the
main track, so that it is electrically separate from it.
Then the reversing gadget sits between the main track power
and the reversing loop. The gadget switches the polarity of
the loop by detecting the brief short-circuit that occurs
and the train wheels bridge the isolating links. The gadget
is quite expensive (£50-100), so you don't want to have too
many loops on your layout.
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