On Tue, 16 Sep 2008 00:19:09 +0100, "Mike Smith"
That's been part of my technique for making the curves and
transitions smooth. Another has been the patent 6' way gauge and
curve smoothing system, a block of wood with parallel shallow
saw-cuts spaced as for a pair of lines at 6' way, which you can run
up and down over the track as you lay it - it settles the curves
What technique do you use for laying them out? Do you cut out semi-circular
pieces of ply or do you draw the curves direct onto the baseboards and lay
the track to that (just going trough the same at the moment)
"Just zis Guy, you know?"
I made templates out of boxboard, easement at one end and true curve at
the other. Total length about 2-3ft, depending on curve radius. One for
each radius is enough - just flip it for right/left hand. You don't need
to be overly fussy about smooth edges - the flex track smooths out any
irregularities in the template.
I like Mike's curve smoother, and intend to copy it.
On Tue, 16 Sep 2008 08:30:49 -0400, Wolf Kirchmeir
Mine, you mean? I'll stick a pic on my website when I get a minute.
It's about 4" long, made of a bit of 4 x 1 PAR. Very simple, a
hardpoint saw blade is almost exactly the same width as the rails.
Why not do it properly? The railway civil engineers do not have 'curves' of
any radius. All curved track on main lines has 'transition' curves which
start at a big radius and decrease progressively to the apex of the curve
and then increase again. My layout is laid out like this so my curves (it's
a big roundy roundy BTW) start around 80-100 " radius and decrease to about
40". You will be amazed at how much better this looks, and how much better
your rolling stock behaves. No train should leave a dead straight and go
into a curve of even 60" radius . It will look wrong.
Actually, the civil engineers use a "cubic spiral" as a transition
between tangent (straight) track/roadway and the curve. Which is a tad
tricky to do in the smaller scales, what with precision on the order of
0.01" required. ;-)
Luckily, there's an easy solution: Flex track cannot begin a curve at a
point, and will naturally produce a transition curve (or easement or
spiral) when curved. So offset the curve about 1/4" to 1/2" _inside_ the
curve at the nominal beginning of the curve. Then lay the flex track to
within 12" to 18" of the nominal beginning of curve, and bend it round
to match the curve about 12" to 18" beyond that point. It will form a
very nice transition curve.
You can use the same method with a thin strip of wood to draw a centre
line for a template for laying down the ballast former (cork) strips.
Transition curves reduce the sideways swing of the coach/wagon ends as
they enter the curve, and so reduce the odds of buffer lock.
I think the cubic parabola (not a spiral) ( y = K*Xcubed) is a bit beyond
most modellers to achieve, and in any case in 4mm at least it is not really
essential. Strictly speaking the transition length required is a function of
the maximum speed and cant on the final curve in question. Again I doubt 4mm
models really need as much cant as you sometimes see on people's layouts. It
looks good, but isn't really necessary - our vehicles are way too heavy
compared with RL and have overscale flanges (except P4).
I disagree about flex track though. I have seen too many exhibition layouts
using it where they did actually get it to look like race tracks. The major
advantage, after appearance, is of course as you point out, less chance of
bufferlocking especially when propelling. The same rules apply to turnouts
BTW. The switch rails are not curved to a fixed radius, they are just like
any other transition albeit a very short one.
One method of getting flex track to perform an semi-automatic transition is
to remove the webs joining the sleepers progressively as you tighten the
curve. ( ie every six sleepers, then every five and so on down to about
every three). I do this anyway to get the track down in the right place.
There's loads of info about this sort of thing at:
Martin knows his onions when it comes to track! Apart from the obvious
references to Templot, there's plenty of general info to be gleaned.
Mind you, why not use Templot anyway - it's a bit over-kill for set-track,
but if you want transition curves etc it's the mutts nuts. It's intended
for those making their own track, but can be a very useful tool for
ready made track too. Works in all major gauges/scales - you can even
make your own up! I believe there are libraries for Peco points etc,
don't know about other stuff, but creating a Hornby set of points
wouldn't take too long once you've got the hang of it.
I'm sure you don't mean that real railways don't have any circular curves at
all? What they have are circular curves (i.e. fixed radius) connected by
transitions to tangent (i.e. straight) track or to other circular curves
(sometimes two different transitions join two reverse curves with no
straight in between). Transitions start straight (infinite radius) and end
at the same radius as the adjacent circular curve.
Well I do and I don't, if you can understand why. Most 4mm curves, even on a
big layout, are so tight that you would never get to the end of a sensible
transition in the space available. My own outfit, which would have ~5ft
radius curves if I laid them out as fixed radii, actually transitions from
about 10ft rad down to about 3ft 6in and then it's time to start opening out
again to reach the end of the curve at the other side of the layout. RL of
course would take the transition to a fixed radius as you note. Even
pacifics will go round 3ft 6in if it is momentary and starts increasing
again. It greatly improves the appearance of your track if curves start with