New Jersey Division Meet

January 18, 1997

3:00 PM

Clinic: Spline Roadbed

Presented by: Mike McNamara

Overview

First, what is the difference between roadbed and subroadbed?

Roadbed refers to the cork, Homasote or other material that the track is actually laid on.

Subroadbed refers to the supporting wood structure underneath the roadbed.

To simplify matters, I like to refer to the whole track support as roadbed.

What is spline roadbed?

Basically, spline roadbed is another type of support for your trackwork. Spline refers to the wood strips that are used in constructing the roadbed.

The splines can be glued to each other or separated by spacers.

The drawing below shows an example of spline roadbed with spacers:

Drawing from January 1987 Model Railroader. Copyright Model Railroader Magazine 1987. Used by permission.

What are the other types of roadbed?

Today, most people who do not use spline for roadbed use plywood. This is an excellent material for this purpose and is better suited for roadbed than particle board or chip board. These products may not offer enough stability over the years that they are supporting your track.

Plywood comes in sheets of course, and many layouts are built on a solid sheet with the trackwork laid directly on the sheet, or on cork, etc.

Drawing from January 1987 Model Railroader. Copyright Model Railroader Magazine 1987. Used by permission.

This is referred to as a Table Top layout. If supported well, a thinner plywood, such as 1/4” or 3/8”, may be used, saving money.

The advantages here are:

· Easy to build

· Easy to get started with track laying

· Solid surface for building on

· Transportable

· Essentially no waste

The disadvantages are:

· No track grades (uphill/downhill)

· Difficult to include bridges

· Not much of a prototypical elevated roadbed

· Limited scenic possibilities

The next step up from the table top is known as the Cookie Cutter, which takes the advantages of the table top method and adds the ability to include small grades. Because the plywood will be cut, it is best to go with 3/8” or thicker plywood.

Drawing from January 1987 Model Railroader. Copyright Model Railroader Magazine 1987. Used by permission.

The advantages of the Cookie Cutter are:

· Relatively easy to build

· Still easy to get started with track laying

· Solid surface for building on

· Transportable

· Essentially no waste

· Ability to incorporate small grades and bridges

The disadvantages are:

· No dramatic track grades

· Difficult to include tall bridges

· Prototypical elevated roadbed available only on raised sections, reducing impact of grades

· Limited scenic possibilities

To many, the best application of plywood as a roadbed is Open Grid construction. For plywood thickness, I have found that 5/8” works well with some 3/4” used for longer spans or moveable sections. Some people only use 3/4”, but this is something that you must determine if your wallet can handle.

Drawing from January 1987 Model Railroader. Copyright Model Railroader Magazine 1987. Used by permission.

The advantages of Open Grid are:

· Full scenic possibilities

· Easy access for track laying

· Solid construction if supported properly

· Ability to incorporate any grade

· All types of bridges are possible

The disadvantages are:

· Waste: Depending on how skilled you are in cutting your plywood sections and how big your railroad is, you may end up with many odd-shaped, unusable sections of plywood

· More waste means more cost

· Possible sagging if not properly supported

Other types of roadbed are also used, including dimensional lumber and foam. These may work depending on your needs.

What are the advantages of spline roadbed?

All the advantages of Open Grid and more, including:

· Full scenic possibilities

· Easy access for track laying

· Solid construction if supported properly

· More stable than plywood

· Ability to incorporate any grade

· All types of bridges are possible

· Smooth radius curves

· No waste other than sawdust

· Precut spline means that roadbed is available for building at all times (no using power saws to cut plywood at 1AM!)

Any disadvantages?

Cutting the spline

To cut the splines, you’ll need to use a table saw, or have someone cut them for you. If you have a table saw and you like using it, or you know someone who will make the cuts for you, this won’t be a problem.

Clamps

It takes clamps to build up the spline roadbed, and the more you have, the more roadbed you’ll be able to build at one time while the glue dries. This will be covered in more detail during the Construction section.

Switch Machine installation

Depending on your choice of switch machines, it may take a little more work to install your machines because of the extra roadbed thickness and having a good area to mount the machine. However, this is not a major problem and once a method is developed, it is just as easy to get the machines installed as it is with plywood roadbed.

Gluey fingers!

Wood glue will get all over fingers while building up the spline. But some people may not mind this!!!
Should spline be used exclusively?

I think not. For yards especially, it makes better sense to use plywood. It can be put down faster and there will be little waste.

Also, staging areas and long, straight sections of hidden track are probably better suited for plywood.

I still prefer to use spline for exposed sections of track, even if it is straight. I find it easier to use the spline and not switch between the spline and plywood. Also, I find it easier to build the scenery up to the spline roadbed than the plywood roadbed.

In general, I think that once you start using the spline, you’ll find it easy to work with and simpler to install than plywood.

What material should be used on the spline roadbed to allow track laying?

All the standard roadbed materials can be used. It is best to try the combination of spline and roadbed material to see how it works before making a large investment.

Cork, Homasote, rubber, vinyl and milled roadbeds should work fine. The type of spline used may prove more effective with some of these roadbeds. For example, spline without spacers will probably be better for the rubber and vinyl roadbeds. Homasote, cork and milled roadbed should be stable enough to work with either spline type. Again it is best to test your method first.

So what type of spline and roadbed material do you use?

Personally, I like to build spline with spacers and apply Homa-Bed on top. Homa-Bed is made from Homasote and is similar to cork in that it comes split in the middle with a beveled outside edge. Straight sections are available as are curveable sections made possible by a series of kerf cuts. The Homa-Bed is about half the thickness of regular Homasote, so this must be kept in mind for any area that Homa-Bed will butt up against Homasote.

Homa-Bed is available direct from the manufacturer and I have always received my order in less than 2 weeks:

BO Manufacturing

73 Schildtknecht Rd.

Hurley, NY 12443

A free sample is available if you write to them; provide your scale.

Homa-Bed is slightly more expensive than regular Homasote, but you are spared the aggravation of cutting the Homasote to size. Too me, that is worth the extra cost.

48’ of Homa-Bed (24’ straight, 24’ curveable) is $28.80 including shipping. Also useful is material for turnouts, a block that you can cut the wedges from. 6 units of this material will do plenty of turnouts and costs $7.50.

For yards, they also sell large flat sheets. I find that for this, I can use regular Homasote, taking care to match up the butt joint to get a smooth transition.

Construction

How do I build spline roadbed?

Hopefully, spline sounds like something you want to try, maybe a small section just to see how it works. Before starting, let’s go over what you’ll need:

Hardware & Supplies

C-Clamps

My advice here is get as many as you can afford!

· 2” clamps work fine for single track. I have 10 but could use more

· 3” and 4” clamps will be useful for multiple track sections

· 6” clamps are good for really wide sections (such as double track with a siding)

· Also, the 1-1/2” spring clamps work good for single track

Table Saw

If you cut your own spline, a table saw is what you need. If you don’t have one, maybe you can use a friends. Another option is to have a lumberyard do the cuts for you. I’m not sure what they might charge for this service, so check first.

If you want buy, I know Mert Gardner has one to sell, so one check with him. Otherwise, you can get a small one from Home Depot. It’s useful for other projects around the house also, so it doesn’t necessarily have to be a train purchase!

Wood Glue

Get the yellow wood glue. It will bond and hold better than white glue. I’ve redone some sections and the wood will split before the glue bonds breaks.

Drill & Screw Gun

You’ll probably want these for basic benchwork anyway, but they will be needed to secure spline to the risers and perhaps to secure a branching spline that is at a sharp angle (too sharp for just a glue bond).

Drywall Screws

These are easiest to use, but still pre-drill your holes. Thin strips of pine will split easily if not pre-drilled. Again, you will probably use these for your benchwork. A box each of 1”, 1-5/8”, 2” and 3” will probably cover all situations.

The Spline

Wood Spline

For the spline you should use clear pine, sometimes called D-Sel. This wood is free of knots and will yield perfect pieces of spline. Other types of wood can be used, but will probably cost more.

I usually buy 1” x 4” pieces that are 6’ long. The price of a 6’ section of D-Sel can be up to half the price of an 8’ piece. A longer piece of wood can sometimes be useful for a long curve where you’d rather not splice two splines together. So look at your trackplan and see if there are any places where it would be better to go with a long piece of spline. You may even want to use some 10’, 12’ or longer pieces.

Another advantage to the 6’ sections is that they are easier for 1 person to cut on the table saw. I was able to start the cut by feeding the wood into the blade, backing it off a bit, and then walking around the saw and pulling the remainder through. Be sure to wear proper eye protection, use the blade guard and kick-back protector, use a scrap piece to feed the wood, and work slowly.

I usually cut a lot of spline at one time to have on hand. A friend of mine made a storage container from PVC pipe with end caps. Otherwise, be sure to store it flat.

I’ll get into the thickness of the spline in a minute.

Wood Spacers

If you go with the spline and spacer method, you’ll need to cut spacers. This is the same as cutting the spline. Cut long strips, and then using a hand saw or radial arm saw, cut the individual spacers. Vary the lengths of the spacers as it is best to have shorter ones on curves and longer ones for straight sections and splices.

I’ll get into the thickness of the spacers next.

Spline thickness

For the thickness of the spline, there are plenty of choices. Some prefer thinner and some prefer thicker. The thickness also depends on whether you go with solid spline or spline and spacers. The idea is to build up the right amount of support for your roadbed material. Start with the width of your roadbed and then determine how many splines. This will give you your spline thickness.

For my spline, I started by measuring the width of the Homa-Bed. This measures almost 2”. I wanted to use the spline and spacer method, so I had to make sure one spline would be centered for the split of the Homa-Bed. I also wanted the Homa-Bed to extend over the outer splines just a little to allow the scenery to be built up under right under the Homa-Bed. What I came up with was 3 splines and two spacers for single track roadbed.

Here is a cross section of my spline roadbed.

Spline Width: 5/16”

Spacers Width: 7/16”

Total Spline Build-Up Width: appx. 1-3/4”

Roadbed width: appx. 2”

Roadbed extends appx. 1/8” over outer splines.

OK, I’ve got everything I need. Where do I start?

Basically, laying out the roadbed is the same regardless of what material you use.

Standard benchwork will be needed to support your layout. This can be Open Gird, L-girder, Shelf sections, etc.

From the benchwork, you must install risers to support the roadbed. The risers should be attached to the benchwork and have 1” x 1” cleats installed.

Use your trackplan to locate the risers. It is best to install one or two, and then attach a few others with clamps before determining their exact height. That way, the risers can be positioned up to the roadbed and then secured.

For a further discussion of building benchwork and installing risers, pick up Kalmbach’s “How To Build Benchwork” book; or look up the January 1987 issue of Model Railroader.

Some risers are in and I am ready for the spline!

The hardest part of spline roadbed is getting the first piece started. Start with the center spline. Use two drywall screws on either side of the spline to keep it centered on the riser and upright. If you are starting on a curved area, use screws and clamps on the other risers to keep it in the exact position you want.

Once this spline looks good, you are ready to attach the outer splines. Do one at a time. Position the outer spline next to the center spline. Put glue on each side of a spacer and sandwich it between the two splines. (If you are not using spacers, run a bead of glue along one flat side of the outer spline and then put against the center spline).

Use clamps to hold the two splines and spacer together. Be sure the spacer does not extend above the splines. Use a level to keep the splines level across each other.

Repeat this process, putting a spacer every 6” and gluing and clamping it. You should end up with something like this:

Now you’ll be limited by the number of clamps you have and how quickly the glue dries.

When it does dry, remove the clamps and add the spline to the other side, putting the spacers every 6” apart. Use a different length spline to avoid having all the spline butt up to additional pieces at the same location. Be sure a spacer is located over the cleat on each riser to allow attaching with a screw. Stagger the spacers so that they are not side by side with the first spacers, but offset instead. When clamping these, put a temporary spacer between the other splines to keep the outer spline from breaking. Keep the splines level with each other. When the glue dries, unclamp and remove the temporary spacers.

At this point the roadbed should be attached the cleats with a drywall screw to hold the assembly in place. Pre-drill and screw from below up into the roadbed.

This is the basic process of building up the spline. Additional spline can be built off of this initial spline. Splice more spline to the ends of the initial piece to continue the roadbed. Clamp divergent roadbed to the initial spline and build up in the same manner.

Now my spline is in, how do I attach the roadbed material?

Before attaching the roadbed material, use a sander or a plane to smooth the top of the spline. You want to know off any glue and irregularities that will cause uneven trackwork later.

Depending on your roadbed material, you will probably have different adhesives to use for attaching the roadbed material. Wood glue can be used for milled roadbed, Homasote, Homa-Bed and probably cork.

For my layout, I’ve been using adhesive latex caulk. This is easy to apply with a caulking gun and probably provides some sound deadening as it dries somewhat flexible. I apply a bead to the top of each spline, and then attach the Homa-Bed, centered on the center spline. Clamp in place, using scraps of wood to avoid compressing the Homa-Bed.

What about turnouts and switch machines?

Turnouts can be located over diverging routes of spline, covered with your roadbed material. The drawing below shows an overview of the spline for a turnout location.

Drill a hole through the roadbed before installing the turnout.

For switch machines, I have always used an underside mounting. The basic problems here are extending the throw rod and securely mounting the machine.

For Tortoise machines, it is easy enough to fashion a new throw rod with steel wire. To mount the Tortoise, I cut a small rectangle of 1/4” plywood slightly larger than the Tortoise itself. I mount the Tortoise to the plywood and then take the whole assembly to the layout.

I position the Tortoise in place so that it throws the turnout properly (2 people make this task much easier). Then I use a couple drywall screws through the overlapping plywood to attach it into the roadbed. Be sure to use only 1” screws here, and add some spacers between the spline if necessary to have a solid surface to screw into.

Well, that’s the basics. I encourage you to give spline roadbed a try. It is not complicated and yields a nice roadbed for your trackwork.

Notes