Struggling with the same question and I'll probably just do trial and error and then give the unused turnouts to a friend or for a later project. Pretty sure I'll be using a #6 turnout for an 18-28 inch radius. Looked for examples here in Chicago, and it seems curves flatten out a bit and are far more organic than the rigid placement on my layout. I'm working on a basic 4 track half circle at the end of the oval with the outer track having a switch for an industrial spur running tangent and at 90 degrees to the legs of the rectangular oval track plan. Again, seems my plan isn't really a thing in reality so one could say my concerns for finding the radius are a bit too specific
Makes you wonder what dimensions the various track design software use. I'll bet it varies.
The one's I complained about here 16 years ago, and which I think may have started this lengthy discussion over several threads now, were the Walthers/Shinohara curved #7 and 7.5 available in 2006. They were considerably shorter in radius in the inner/diverging route than advertised, something close to 4 full inches. They were nice turnouts, functioned well, but there was another problem due to their curvature: blind tires, such as on the BLI J1 2-10-4 and on their T1 Duplex 4-4-4-4 (both middle axles blind in the twin drivers sets), the drivers ran inward, down the radius, at the frog. This meant that their tires spanned the thin plastic DCC-friendly spacers, and there was an instant short. So, not only did I have to mangle the ties under the inner route to widen it, but I also had to gap or paint at the frog.
I don't know about the latest issue. My hope is that someone at Walthers caught wind of the various complaints and actually did something about it.
I watched a 2 hour interview with the Forum's own Byron Henderson (search Youtube TSG Multimedia) and he wasn't so sure that people who proposed to lay their own turnouts, actually got the job done.
He also said your layout radius is not your largest radius curve, but your smallest.
To the OP's question; we need a sticky with the advertised radius vs the real radius, by manufacturer.
Henry
COB Potomac & Northern
Shenandoah Valley
I have seen many similar questions on this forum with many differing answers and I always wonder if modelers ever find the exact curved turnout they were looking for.
Because of a rather restrictive budget, I had to learn to hand lay the 50+ turnouts on my 18' by 19' double deck HO scale layout. Several situations arose where I needed to construct a custom turnout to fit a specific situation. Fortunately, I discovered that once I learned to build a standard #6 turnout, I then had the skills to build ANY type of turnout! I would first draw out the required turnout to scale on paper. I would then use rubber cement to temporarily glue the PC ties in place on the drawing, then lay the rails following the drawing and using a track gauge to make sure everything works. The result: almost 50 left and right #6 turnouts, two curved turnouts (can't remember the radii), a couple of constant radius diverging route turnouts to meet a helix, one constant radius "wye" turnout at the top of a helix, and even a three-way turnout entering a staging yard.
Just remember that, if you can lay flex track and solder feeder wires to the rails, you already have the skills you need to hand lay turnouts.
Hornblower
Knowing that the old "Walthers Shinohara" curved turnout radius was narrower by 2-4 inches on the inside curves, how does the new line called "Walthers Track", an entirely new product, stack up in actual dimensions? Are they truly 20/24" and 24/28" or are they also lower than they say when actually measured like the old line was?