have just re-read a note suggesting that 6 ft is a reasonable minimum
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
In message , peter abraham writes
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 layout.
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.
HTH
"peter abraham" wrote
I've no problem with any of my modern (mainly Bachmann, Hornby & kit-built) stock with Peco code 75 medium (3'0") radius points.
John.
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. Keith
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.
Alistair
Thans for that
Mike
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.
Cheers, Mick
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.
What is a "second radius" in inches or centimetres?

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