have just re-read a note suggesting that 6 ft is a reasonable minimum
radius to aim for.
I have a 7m x 4m room all to myself and cannot contemplate anything
larger than 1 m radius without running out of space.
However non of my very varied rolling stock likes less than large
radius points (peco).
In message , peter abraham
What stock are you talking about. Both Bachmann and Hornby stock will go
round "second radius" curves which are much sharper than the 1 m. you
mention. Build your layout with 1 m. minimum radius curvess, and Peco
large radius points and you'll be OK.
The constraint on radius is the length of the rolling stock. Scale
length carriages look best at around 1m radius or larger. 1.5m and up is
even better, if you can manage it.
There is also the problem of buffer lock and gangway lock if you use
scale operating buffers and gangways. You can't go much below 15.m
radius with those. If you use the variable-close-couplings made by Roco
and others, you can get away with 1m or thereabouts.
The shape of your layout table is constrained by
a) the location of the entrance to your room; and
b) your willingness to have at least one "duck-under" entrance to the
Your room is plenty large enough for 1.5m radius curves, depending on
how you arrange the track.
In your space, you can fit a very nice two-lobe layout, with the lobes
offset from each other. Sort of distorted U shape with fat ends on the
legs of the U. With judicious arrangement of the walkways around the
lobes (at least 3 sides accessible), you can have a "walk-in" layout.
The space is ideal for an around-the-wall shelf layout, with possibly a
lobe or two extending into the room.
NB that in layout design, it's best to think in terms of scenes
separated by things such as overbridges, cuttings, tunnels, and so on. A
long scene can be subdivided into "areas of interest." A major advantage
of a shelf layout is that you _only_ the track in front of you, which
helps the illusion that it's a long way from the track behind you.
Six feet is a very utopian minimum radius for 00, most of us have to
manage with rather less in P4, I have more or less 4m square and my
minimum is 1100 mm. This still allows main line trains to run at full
scale speed in P4, in 00 you can reduce this, mainly depends on your
choice of couplings and whether you want your gangways in contact.
750mm will probably be OK for most as long as you use transition
curves and avoid reverse curves at the minimum radius, eg crossovers.
The important thing is to use transition curves. You will need to use
flexi-track for this. I have large 4-6-2 locos which can get round 29 inch
radius curves if they are led into them gradually. Transitions are more
prototypical and look better as well. It is obviously better to use the
largest radii that you can fit in but again the transition is a good idea.
It also depends on how much reversing you are likely to do. Most of the
problems of buffer locking are not caused by using 00, EM, P4 or whatever.
The big problems occur particularly when axle standards are "sloppy". In
that the rolling stock is allowed to move sideways on the axle, thus
multiplying the movement of the buffers. Tighter wheel standards will also
help - as mentioned elsewhere many times within this group, the critical
dimension is the flange root to back of opposite flange. When it comes to
slop on the track, an equally critical dimension, is the flange root to
opposite flange root measurement.
My Hornby Stanier and Pullman stock fitted with Keen couplers and gangway
ends work fine on tight curves; my Gresley coaches with Keen gangways but
Kadee couplers experienced gangway lock on a 2nd radius reverse curve, but
by modifying to a larger radius with a short staight section in the middle
I solved the problem in only a slightly larger space.