Spline roadbed

[Anonymous]

I am building my HO scale layout using the spline method.Where can I find some web sites that demo turnout methods and also spherical helix using spline method. I am using poplar 3/16" by 3/4' for my splines. I use 3/4" x1&1/2" spacer blocks every 16". I want to do a 2 line main so my roadbed needs to be at least 5" wide. Is this correct?

Thanks
Joe mcDonnell

[ndbprr]

I don't recall ever seeing a helix made using splines. It will be difficult as you have a horizontal curfve element and a vertical rise element. Seems like plywood with spacer blocks would be easier to me. As to width that will be a function of the radius which you don't mention. 5" seems a little tight to me unless you are using 40" or larger curves. If I assume 2 1/2" centers between the tracks you will have some overhang on the inside at the center of the car and end hangover at the ends on the outside. So 2.5 +.75x2 for the distance from the centerline of the track to the outside = a total of 4" plus space for the overhang I would be more inclined to go 6" but I would set up some track on a flat surface and try some long cars on it to know for certain then there will be no surprises.

[Anonymous]

To ndbprr,
Thanks for your reply. I thought 5" was too narrow,On my spherical helix what I am doing is I,ve built 3 octagons, one is 8' in diameter,another is 6 and the last is 4'.I intend to set these all at the same height , 48" and mount dividers with 1x4 risers mounted to them and use these to get my elevation 2&1/2%.. In making my splines I am using poplar which is knot free and I am ripping it 3/16" X3/4. Ithen soak it inside a piece of PVC for 24 hrs and it bends pretty good, better than white pine.I use spacer blocks betweenn each spline glued and nailed to the riser. Let me know what you think..

[wp8thsub]

I built a lot of spline using 1/4" clear redwood, which works OK down to 24" radius or so, but Masonite works MUCH better at any radius. I cut 1" wide strips of 1/4" Masonite. Compared to wood it bends more predictably. With wood I was finding that curves could try to change a little in the middle of an arc due to variations in the density of the wood, while Masonite always gives smooth results. As long as you already have the poplar pre-cut, go ahead with it and the spacers. Your overall method sounds fine.

A description of spline construction and some photos are on Lee Nicholas' Utah Colorado Western site: http://www.ucwrr.com/construction.htm

[ndbprr]

I've gone back and forth on a helix more times than I care to admit at this point. Still don't know yet if I will or won't but I have given a lot of thought to one and if I do it is going to be at least 36" radius and probably 48". Either way access to the center will be critical and I plan to use plywood and hang it from threaded rod with double nuts under each suspension point. My logic is that it is the same as a duckunder and it will be easier to acces the center and adjust it if needed.

[cwclark]

I don't know about websites, but the Kalmbach publication "Model Railroad Benchwork" has a section in it regarding the building of splined roadbed.. the distance between track? that is close,..I'd go with 4 3/4" in straights and 5 1/4" in curves...which will make it a 2" center to center on straight track and 2 1/2" center to center in the curves with a 1 3/8" overhang ....Chuck[:D]