Has anyone tried gluing a spline under ¼ inch plywood roadbed, to save weight?
By glueing a ¼ x ½ inch strip under each span, with the ½ inch dimension vertical, it should give a lot more stiffness without much weight. It should avoid kinking at the riser since it’s not attached to the riser.
Does not reduce vertical clearance since it is not thicker than the support cleats.
Thanks for your thoughts,
more-ore
Seems to me like that’d work fine. Specially if your joints were between risers and the 1/4"x1/2’ joints do not match the joints in the roadbed. Might be even stiffer if you glue another 1/4"x1/2" strip under the vertical spline. One thing to remember is we tend to overbuild in order to support not only trains but construction activities that involve hammering and leaning on the benchwork. Always a problem if you have a long reach somewhere. BILL
Hi. What you are proposing sounds OK. It would be much like the L-girder framing a lot of modelers use, but I can think of a couple of concerns…
The 1/2" dimension sounds a bit small. Plywood is rather fragile in small widths.
Is your layout flat, or are there inclines? If it is flat, then you won’t have any interesting measurements where you go from the level to the incline to get the vertical easements right. If not flat, it sounds like fun, and the kinks at the risers will be hard to avoid.
If you have a reasonable run between supports, you may want to consider 2 splines, 1 under each edge of the 1/4" ply to cut down on side-to-side wows or rolls. At this point, you are getting close to the material required to try something more substantial, like cutting a second 1/4" ply subroadbed and gluing it on top of what is already there. Make sure the joints in the second layer are not within 4-6" of those in the other layer. That would give you the effective strength of 1/2" ply. An added bonus in having more mass is the deadening of sound transmission in the subroadbed.
My own sub-bed is this 2-layer sandwich of 1/4" plies. Think of an 11’x14’ cookie-cutter layout that crosses over itself to make 3 levels. The subroadbed is 3" wide, but I’d use 3-1/2 or 4" next time so my supports could be farther apart.
I may have missed a point here; the reason for saving weight. Model Railroader has had a few articles on travelling layouts. Ruggedness means a strong, not necessarily heavy frame, and a light plywood subroadbed topped with extruded styrene (pink or blue) can give good results. A lot of the weight in a layout is in the scenery materials you plan to use. Keep that in mind too.
Good luck on your planning. It’s always best to play devil’s advocate and
Increasing the width of the subroadbed slightly as noted will have a very modest effect on strength and ability to increase support spacing. Increasing the depth is the most effective approach: however, then the subroadbed will become stiffer and less flexible.
Dante
I have cookie cut thin plywood (5/16" I think) supported on (approximately) 16 inch centers, “Stiffened” by a caulked-on layer of fan-fold underlayment (3/8" or so extruded foam) carved to roadbed contours. Those places which developed unacceptable vertical aberrations were beaten back to level with a length of steel angle iron screwed on from below. That supports 16.5mm gauge flex track, and hand laid on wood ties specialwork, and also provides mounting for screw-eye guides for the fishing line that moves switch points.
Why steel? Because that’s what all of my benchwork is made of. Forest products are adversely affected by the high temperature and low humidity of local summer climate. Likewise, cork roadbed is a non-starter - it dries out and crumbles - but, so far, extruded foam doesn’t seem to be adversely affected.
Chuck (Modeling Central Japan in September, 1964 - in a Mojave Desert garage)
If your using 1/4" plywood for subroadbed you had better stiffen it up with something as that stuff is going to twist and sag over time. I use 3/4" birch plywood in the sections where I have chosen to sue plywood subroadbed the rest of the layout is 3/4" spline subroadbed made from pine strips laminated together with hot glue to spacer blocks. Some may say 3/4" is too heavy and you can get away with using 1/2" probably true but think about all the extra work your doing. If you just used a thicker piece of plywood for the subroadbed initially and fastened it to your risers securely with drywall screws how much extra weight to you think it would add? Your bench work weather it be open grid or L-girder should be constructed so that it can support the weight 3/4" plywood with no problems if it isn’t you are in for big trouble down the road.
Greatly appreciate your inputs, maybe I can learn before doing, for a change? This layout is based on an article in Model Railroader in July 1952 by John Armstrong – “Convolutions & Western RR.”
It’s a Helper District, HO layout size 5’9” x 9’ with helix, hidden staging tracks, and switchback ore mine branch. Mainline grades 3.6%, 20” min radius, 4 levels starting at 48”, top elevation gains 14.5”. Mucho action for this size…mainline run is 60 actual feet. Making it portable with 4 modules is a tough challenge. Roadbed stiffness & weight are critical.
Thanks again,
more-ore
You mentioned making it in four modules is this layout going to be movable or portable so it can be taken to shows and be displayed etc? f so I can understand your concerns for keeping things as light as possible. But my concerns would be sacrificing strength in the name of saving weight You have to remmebr your going to still be adding more weight to it when you ad scenery, structures etc. doesn’t sound like a lot but it’s the sum of all the parts that is the thing you will have to worry about.
Perhaps a way to save weight and still make it strong would be to use metal studs instead of wood for the initial bench work. Maybe look into spline roadbed like Joe Fugate uses by making it o