I'm helping my son build his first new HO layout on 4ft wide sheet's of plywood, the question is what degree of curve track will fit for the widest outside track, and what size will work for an adjacent secondary inside track?
Thanks
Hello, and welcome. The curves are measured by their radius outward from a central pivot point in our scales, unlike the real railroads that tend to use degrees of curvature and radius at times...depending. To answer your question, on a 48" wide sheet of plywood, 22" curves would give you a 44" diameter, and still leave you some clearance outboard of the curves to place some catching device or material in case items derail along the curve and might continue to roll sufficiently that they fall to the floor after only 1.5". Remember that the radius is measured from the central pivot point to the centerline between the rails.
With tight clearances between parallel rails along that outer curve, the inner curve could be as much as 19", perhaps a bit more, maybe less...and that depends on what items you run around both rails on the curved portion at the same moment in time. Bigger items may side-swipe each other because of the protrusion of end bits, at the corners on the inner track items making contact mid-body with the items on the outer track.
If you're using commercial sectional track, then you can get curved pieces in 22" and 18" radius.
Chris van der Heide
My Algoma Central Railway Modeling Blog
Thank you for the reply's
Looks like we will be going with Kato unitrack, and using 18" & 22" curve's