Hello Looking (maybe) for a lower level with a staging yard in a reverse loop, using Kato Unitrack Is using #4 turnouts and 11R radius (282mm) for the inner curve a recipe for disaster?
Number four switches are pretty tight. No, they aren't as tight as 11" radius overall. But when you attach a right hand switch to the curved leg of a left hand switch, you create a reverse or ess curve. Those aren't good things, even without points and frogs in them. I'd be tempted to go clear up to number eight.
No, for staging, you should be traveling nice and slow, anyway. You will want to make sure the #4 has been adjusted, ahead of time, to ensure the points sit cleanly into the stock rails.
This is the same concept, still using #4 but the inner curve is 12.375R (315mm)....By the way, the turnout to enter the loop is a #6
Why the added straight? That shortens your staging tracks more than using longer switches. That first switch, a left hander, doesn't lead directly to a right hand curve, so a longer switch isn't so critical there.
#4 switches' diverging routes are 19R. The same back-back #4 S-curves is employed in Kato double track single crossovers, which do not have problems with derailments, even at speed. The S-curve is roughly the same severity as an uneased transition from 9.5R to straight track, and Kato locomotives are rated for 9.75R curves. I wouldn't worry about it. The 11R inner radius is not a problem. 89' cars will not look very good on it, but this is staging; who cares? Even if you do, just keep 89' cars off of the inner track. French_Guy's solution for a 12.375R inner radius will require cutting a 15R30 curve down to 15R15, to fill the gap shown. You don't want to just cut one end off of a 15R30, because you won't have a Unijoiner pocket left in the cut end. It's easier to take the length out of the middle of the track piece. It's a lot easier when doing this on straight track, but lay the piece to be cut down on a work surface upside down (rails down). Hold a second piece of 15R (remove unijoiners) also upside down, over the one to be cut, using the end of the second piece as a guide helps guide a fine tooth modeling saw's cut square and true. The hard part is figuring out how much of the middle of the curve to cut out (half the circumference). You do not have to cut out the exact middle, just a section that is half the turn (15 degrees). If you have a pair of dividers, you can probably use them to mark the exact middle of a 15R30 from either end (adjust them so they reach the same point on the circumference from either end of the curve). With that setting on the dividers, you can mark off any 15 degree span in the (roughly) middle of the 15R30 to be cut. Once you've got the roadbed cut, roadbed ends slid together on the rails, rails trimmed to length, and it fits in the space correctly, glue the roadbed halves together.
I'm not too concerned about cutting a piece of curved track, since I did it already and it went well https://www.trainboard.com/highball/index.php?threads/cutting-kato-curves.131753/ I do not have any 11R track on hand, so I can't evaluate how a long engine or passenger car will look like on such curve Anyone would have some pictures to share?
John Sing (@atsf_arizona ) posted photos of the fix years ago. I can't find the thread right now with a quick search (sorry). EDIT: Found an external link to his photos and description https://www.pbase.com/atsf_arizona/image/151545252 Basically, you need to notch the stock rail where both points meet it, so that you create a pocket for the point to sit into. Use a good sharp file, and work the area carefully. It isn't difficult, but don't rush yourself
