Styrosplines

[kelticsylk]

Frank, I also bet that with warm weather coming, leaving the splines in the sun would make for eaiser bending too for someone with smaller curves.  I would also consider a 45 degree angle on the ends to create a "glueable" overlap, much the way a long piece of moulding is installed where a joint is required along a long wall.  Carpenters eliminate a butt-joint this way.

The angle joints in wood molding are usually used as a "cheat" when you need to use shorter pieces. If you use a butt joint it's VERY visible when the molding contracts. It will also bulge as the wood expands. With the mitred joints the two pieces slide past each other. The gap is less visible and the bulge not as prominent. Don't usually glue the joint. It would defeat the purpose.

The only exception might be the foam molding they have out now. That stuff is pretty inert. Gluing it solid wouldn't make any difference.

I'm gonna try and curve a piece as tight as I can without snapping it. I'll check and see if heat will help.

[kelticsylk]

One concern I'd have about foam splines is strength. Some of us are clumsy, and I'd hate to see what might happen if one stumbled and instinctively reached out to grab a spline and---

I  hadn't thought of that..It would be pretty easy to repair in it's "raw" state, just cut out the damaged part and replace. On a finished layout, this might definitely be an issue.

Make the scenery stronger than the roadbed? Gaurdrails? Crashbars? The layout might end up equipped with "case savers" like they use on motorcycles

Have to think on this a while.

[Lemosteam]

You could finish off the outsides of the spline with a strip of luaun to add vertical stiffness.

Great Idea on the cutting fixture!

[kelticsylk]

Couple of additional things...

I revised the cutter, now called ThingX.1, by adding an aluminum channel to keep the spline 1 7/8" high. This matches the height of the pink slab. This should make the transition between the two types of construction easier...




I also tested the spline to see how tight a radius it could form...


I think that radius is actually smaller than 3". The parabolic shape the spline took results in a VERY tight curve with easements. I went smaller but the spline snapped. I'm pretty confident that the typical curve radius used on a small N scale layout could be constructed without issue.

Real construction of the new roadbed begins tomorrow. I'll keep you updated here and at Milepost 15 (http://kelticsylk.blogspot.com/)

[kelticsylk]

ThingX.1 certainly does the job. The screws I had on hand were too long so I used nuts for spacers instead of the lock washers shown in the drawing. Actually makes it look a bit more "industrial", almost like a real tool ...






Only took a few minutes to cut 40 splines. The aluminum channel came from another project that's on hold. The straightedge is an ancient two piece aluminum one made for drywall. I used it for cutting wood with my circular saw before I got my table saw. It was old school, but I swear I got straighter cuts back then.

I'll be installing roadbed over the next week or so. Trains may be running soon!

[LV LOU]

I also tested the spline to see how tight a radius it could form...


I think that radius is actually smaller than 3". The parabolic shape the spline took results in a VERY tight curve with easements. I went smaller but the spline snapped. I'm pretty confident that the typical curve radius used on a small N scale layout could be constructed without issue.

Real construction of the new roadbed begins tomorrow. I'll keep you updated here and at Milepost 15 (http://kelticsylk.blogspot.com/)

Tell ya what,you'd never be able to do a bend even CLOSE to that with the pink foam..It's hard as a rock..I doubt you could even do the spline system with pink or purple foam..

[kelticsylk]

You could finish off the outsides of the spline with a strip of luaun to add vertical stiffness.

Great Idea on the cutting fixture!

John,
Great idea on the luan. I tried a variation on this idea. I used hardened foam lattice strips I found at Lowes. These "hard" splines add quite a bit of "umph" to the roadbed. I used just over 40 pounds in this test...


There appears to be some vertical compression of the blue foam, but I think that will disappear when I actually laminate the hard splines to the "soft" splines...


I made sure to clamp everything in place so to get a better representation of the final installation...


These are the types of construction I intend to use for various track sections...


Dave,
Look like a solution to your concern? While I'm sure it'll support trains, scenery, and the occasional grandchild I'm not willing to commit to a falling test at this time 

Thanks to all you guys for your comments and suggestions. They are invaluable.

[robert3985]

Although this is a very interesting thread, splined subroadbed is nothing new.  There are all kinds of materials to make it from, and all of my subroadbed (except in yard and large industrial areas) is splined 1/4" & 1/8" Masonite cut into 1" splines.

I've been doing this now going on 20 years and several of my model railroad cohorts here in Utah and elsewhere also utilize splined Masonite in both N and HO.

Like DKS, I worry about the strength of Styrofoam splined subroadbed and the sag photos you've posted clearly indicate it's not very rigid (to say the least).  Yup, it'd help to put something with more structural strength on the outsides and in the middle, but the Styrofoam is not really great as a structural element in anything designed to be stable....which is what model railroad subroadbed is supposed to be.

Another help would be to increase the density of your risers.  Some of the spans I'm looking at look waaaaaay too long.  I'd be afraid that the splined roadbed over the years would start to sag on its own between some of your longer spans.

My splined Masonite subroadbed, glued together with either yellow hot glue, or yellow carpenter's glue will support me (245 lbs), balancing with one foot in the middle of a 12" span.  Deflection is about 1/16" to 3/32".

It's been a while since I bought a 4X8 sheet of anything other than 2" Styrofoam, but I'm guessing that 1/8" tempered Masonite is comparable or less than an equivalent sheet of 1" foam price-wise, so...it might be cheaper than foam.

One thing's for certain...it's a helluva lot stronger, and it also deadens engine and track noise more than any other material I've ever used for subroadbed.

But....I'm a real proponent for building benchwork and subroadbed out of substantial materials, like plywood, premium pine, redwood, and Masonite...gluing and screwing everything together. You may not be.

[daniel_leavitt2000]

Yep, this is it. This is what I plan on using for my layout. Waterproof, lightweight and inexpensive. I'll add this to my PVC benchwork idea and i can eliminate wood almost entirley.

In addition to glue, I see you use black bolts to hold everything together. I am thinking some sort of plastic bolt, like the friction bolts that hold interior door panels onto vehicles. Also, what about a small luaun platform supports under the  spline? This would spread any shock received by heavy objects falling on the roadbed.

[LV LOU]

What he said. One solution: a hot wire cutter. You can get them that look like a jigsaw cutter for slicing large sheets into strips. Or, I also use a packing knife. But sawing foam? Nope.

One concern I'd have about foam splines is strength. Some of us are clumsy, and I'd hate to see what might happen if one stumbled and instinctively reached out to grab a spline and---

 
Bet that saw would look like this!:



I made it for cutting all the foam on my railroad.Just a table made from wood/masonite,and a loop made from 1/4 inch steel rod stock.The cutting wire is Woodland Scenics,the power supply is from an old Power Wheels kids car.I actually did all the longer,straight cuts in my garage with a small,battery powered saw with a razor sharp carbide blade.Really didn't seem to make much dust,but I did do it with the garage door open,LOL!!!

[Lemosteam]

Yep, this is it. This is what I plan on using for my layout. Waterproof, lightweight and inexpensive. I'll add this to my PVC benchwork idea and i can eliminate wood almost entirley.

In addition to glue, I see you use black bolts to hold everything together. I am thinking some sort of plastic bolt, like the friction bolts that hold interior door panels onto vehicles. Also, what about a small luaun platform supports under the  spline? This would spread any shock received by heavy objects falling on the roadbed.

IMHO, wood presents it's own share of issues.  When I build my final dream layout this will be my method as well.  This would work really well for splined modules too.  Ever lighter materials will make transporting them easier and easier.  The added rigidity of the strips puts it over the top.

Frank, have you done any delamiation testing?  If you put a drywall screw through the foam into the strips, it should never delaminate and would totally eliminate any clamping.  The screws give the screw something to bite into (and one of the reasons I thought of using luaun).

[Lemosteam]

 
Bet that saw would look like this!:



I made it for cutting all the foam on my railroad.Just a table made from wood/masonite,and a loop made from 1/4 inch steel rod stock.The cutting wire is Woodland Scenics,the power supply is from an old Power Wheels kids car.I actually did all the longer,straight cuts in my garage with a small,battery powered saw with a razor sharp carbide blade.Really didn't seem to make much dust,but I did do it with the garage door open,LOL!!!

Lou, that hot wire "saw" is damn brilliant.  Clamp a fence at a specific distance and you have a ripping tool.  How quiclky can the foam pass through the wire?

[Zox]

Like DKS, I worry about the strength of Styrofoam splined subroadbed and the sag photos you've posted clearly indicate it's not very rigid (to say the least).  Yup, it'd help to put something with more structural strength on the outsides and in the middle, but the Styrofoam is not really great as a structural element in anything designed to be stable....which is what model railroad subroadbed is supposed to be.

In the model-railroad press, I've seen Masonite splines with spacer blocks used to support Homasote roadbed, which is heavier and more likely to sag than foam.

Filling the open space between spacers with foam instead of air will certainly be at least as strong.

[kelticsylk]

Yep, this is it. This is what I plan on using for my layout. Waterproof, lightweight and inexpensive. I'll add this to my PVC benchwork idea and i can eliminate wood almost entirley.

In addition to glue, I see you use black bolts to hold everything together. I am thinking some sort of plastic bolt, like the friction bolts that hold interior door panels onto vehicles. Also, what about a small luaun platform supports under the  spline? This would spread any shock received by heavy objects falling on the roadbed.

Daniel,
The black "bolts" are actually drywall screws. I use them as "clamps" to hold the foam together while the glue sets. I just push them thru. They are cheaper then a real clamp, so cheap that I can leave them in place.

[kelticsylk]

In the model-railroad press, I've seen Masonite splines with spacer blocks used to support Homasote roadbed, which is heavier and more likely to sag than foam.

Filling the open space between spacers with foam instead of air will certainly be at least as strong.

I think that is a great idea. Saves the aggravation of cutting all those blocks and only serves to strengthen the whole structure because it becomes a solid mass.