I have never installed a turntable on a layout and I bought the built up Walther’s 90 footer one this week with the “recommended” Cornerstone 3 Stall Roundhouse. The roundhouse is about 14" deep and the instructions suggest that the stall tracks depart the roundhouse at a 10 degree angles to meet up with the lip of the turntable to be in proper alignment with the bridge track. They suggested 5 3/16" of track between the turntable and roundhouse.
Question: after the loco departs the turntable outbound, how much straight section would you recommend before entering a radius, and what is the smallest radius I could get away with once I depart the straight section?
The largest steamer I could go with is a 2-8-2 or something along that size I suppose. The radius I would be negotiating is 24", nothing smaller.
Thanks, this is my first experience with this layout feature. I know you have to be patient and exacting when installing these items, any tips would be appreciated!
If your trackwork is good enough, you can curve right up to the turntable, as long as the end of the approach track is tangent to the bridge track. From a more practical standpoint, I’d suggest a couple of inches of straight at the turntable at least.
Thanks Brunton. I was hoping that was the case, but when moving steamers on and off the bridge track, some straight will be a good idea and probably make the operations more reliable. The good news is that I think I can squeeze in about 12-15" of straight track before entering the 24" radius.
The layout I am constucting has a minimum radius of 24" and that is only on a siding, or in this case the entrance/exit to the turntable/roundhouse location. The balance of the layout has minimum radii of 26-32".
The goal with my new layout is to run my collection of steamers. I have a a few W&R Brass units that have DCC and Sound installed. They run beautifully and look incredible. I am getting too old to just leave them on display, it’s time to run the heck out of them (responsibly of course) and enjoy them. Then the rest of the collection consists of a variety of makers, BLI, Heritage, Lionel Big Boy, Trix 2-8-2 and a few different Spectrums. The steamers being made today all seem to run pretty nice.
I leveled in the subroad bed carefully and because of the amount of distance involved on this layout, I did not change grade. The open grid will provide plenty of opportunity to create gullies, ditches and undulations that a flat piece of plywood can’t do.
I did a plywood jigsawed (cookie cutter) subroadbed mounted on open grid benchwork with risers. I started putting down the Homabed branchline roadbed on my centerlines last night. I am using Walthers Shinohara Code 83 HO flex and all #6 turnouts with Caboose Industries manual switch stands (the entire 10x12 nearly square donut layout will only have a total of 5 turnouts). The layout will be powered by a Digitraxx Super Empire Builder, 14g buss, 20g feeders.
Keeping it simple and clean for smooth operations…
There can be a bit of a learning curve to installing a turntable, but a few reflective pauses and breaks during the work can really help to get over any puzzles.
Aside from the distance between the ends of the bridge rails (…remember…this is where the bay rails end up, tight to the inside lip of the turntable pit) and the roundhouse, and the angles you may have to shim or force/nail/glue to get everything doable, there could be some shimming under the lip of the turntable pit to help rail heights meet level. For example, I use flextrack right to the backs of the bays, but necessarily removed the first two ties at the pit lip so that the rails would meet. Also, I used Code 100, but the bridge rails are Code 83. So, you might guess that I had to modify something. What I did was to use a thin grinding disk (not a cutting disk) on a hand tool and ground shallow grooves for the higher rails on the pit lip. A dab of glue below them, and they have worked just fine.
Generally, I agree with Mark, care in laying the tracks and with their alignment throughout should negate almost any curvature issues, except for perhaps very tight approaches, say in the 17" range. For that reason, I strongly urge, just to give yourself a bit of a break, to try to keep a curved approach broader than 24", and the final 2" tangent. Even then, a larger steamer (we all get one eventually) will want to force the leading truck to the outside of its path on tight curves, and that means a short tangent will have a salutary effect in preventing the truck from kicking the bridge sideways to the extent that internal gearing on the bridge pivot will permit…usually enough to make the first driver derail…fun, mmmm!
As stated you could curve right up to it but I think it looks better with a straight run up. I’d try and go the length of my longest loco.
We talk about how un-prototypical big 6 axle units look on 18" curves when I’ve seen some REALLY tight turns going into fueling racks and maintenance sheds. Tight enough to make you go WOW when you see a big AC4400 on them.