I'M currently planning to draw up a trackplan for a HO scale railroad.The size will be approx.16'x6'.I'm having trouble figuring out what kind of curve radius I can expect in a 6' turnback.I am concerned about my new RAPIDO BUDD COACHES getting around that curve.they are close-coupling,and I do not posess a radius tool.any suggestions or help will be greatly appreciated.:question:
This is far less complicated than you think. Your layout is 6 feet wide. That is 72 inches. So if you could somehow lay track right to the edges, the diameter of the curve would be 72 inches. Radius is exactly one-half of diameter. One-half of 72 is 36 inches. That's your radius. Now in reality, you can't lay track to the very edge of the layout, not unless you want to risk your nice trains falling off the layout and hitting the floor. So you can't use all 72 inches. Let's say you lay track no closer than 4 inches from all edges. Now the diameter is 72 minus 8 (because you are staying 4 inches from the edge on both sides). 72 - 8 = 64 inches diameter. One-half of 64 is 32 inches. So by staying 4 inches from the edge, your radius is 32 inches. In simple terms, radius is always one-half of diameter. The only tool you need is a tape measure to measure the width of the layout where the curve will be located. Subtract the distance from the edges. Divide by 2 to get the radius. The diagram below may help. - Jeff
Remember that radius is always figured using the center line, (the middle, between the rails), of your track. Using 32" radius would be the absolute maximum, and would leave little more than 3 inches from the end of ties, to table edge. This is getting plenty close. Myself, I'd want to set back a little more than that.
And then are some that refuse to worry about edges and incorporate four foot falls into our layout plans. I do this all the time and have never lost a loco yet. I like the above diagram for ultimate "safety" however. Jim
6' = 72" or 36"R but that's too big to get all the track in that space. Most HO modelers ca 1.5" space to get all the track w/in that space. That leaves the C/l 7o C/L 68" or 34" R.
Thanks guys for the really helpful info.I will probably go with 32 radius as JEFF suggested,as I want to stay off the edges,using that for foreground scenery.that will help with the passenger train,but I have to be mindful that this layout will be expanded in the future, to a size of approx.36'x12'.
As Boxcab mentioned above, track measurements customarily refer to the centerline of the track. So if the centerline has a 32-inch radius, the outside edge of the track will be a bit closer than 4 inches from the edge of the layout. You will have more like 3 inches between the outside edge of the track and the layout's edge. - Jeff
Gorgeous to look at. Wonderful work! Sadly, not everyone else negotiating edges has your construction and track laying abilities. So a visit to the floor of something is in their future...
Jeff, Yes, a brave train crew, but I don't have a problem. All my curves on my layouts that are "on the edge" are all super elevated. By placing a thin strip of wood under the outside ties every other inch you can make your layout "train safe." By using scenery and "on the edge" modeling you can make a larger layout than you originally thought you could. I suffer from only a 10x11 spare bedroom so I have to build to the edges to get as much railroad as I can. Jim
You have the train you are building your specs to. It seems like the best plan is to do some testing on your trains and see what they do. Get some track and make some ovals and run those trains.
