Diameter of circle

[Buks Viljoen]

I'm busy with the planning of a HO scale track layout. What is the ideal diameter of the curve of the tracks at the end of the layout? Some say 75cm others as little as 55cm.

[Steve Smith]

Hi Buks,

For HO scale the recommended minimum radius is 612mm (24 inches), but it is dependent on the wheelbase length of the locos and rolling stock you plan to run.   Longer rolling stock looks and runs better on larger radius curves.   You can use tighter radii, but the appearance is toylike and you may find that longer wheelbase rolling stock may bind or uncouple on tight curves.  Laying track with easements can improve the tracking of rolling stock into tight curves.

As a rule of thumb, aim for the largest radius that your space will allow for.   To try out your locos and rolling stock on curves of different radii, mark a sheet of polystyrene with 180 degree curves (spaced at 25mm intervals) from 600mm up, and pin flextrack to the marked centrelines to see what you can live with.

Good luck,
Steve

[capeklr]

Hi,
55 cm is way to small.
Most manufacturers have set track and the smallest is normally 360 mm radius making
it a 720 mm diameter or 72 cm.
What trains are you planning to run?
Why I ask because these small diameters are more suited to smaller locos and coaches.
Happy planning.