Splines, Cookie Cutter or Plywood



I am a newbie from New Zealand and currently constructing bench work.  To date I have the bench work made from a grid of 3 x 1 at 12" centers. I am now pondering the roadbed ( I plan various elevations of track work) and looking at the options of:

1. Splines,

2. Laying a sheet of 1/2" ply and then cookie cutting the roadbed, or

3. Laying 1/2" ply and building up the roadbed using extruded foam.

Having read many of the other posts in this forum, I quite like the idea of spines but the big negative appears to be - how do you lay out your track work over a bunch of big holes?

I also see that the most common type of spline appears to be a laminate of several pieces of 1/4" hardboard but I would guess that getting track pins into that material would be difficult at best.  Has anyone thought of using Medium Density Fibre board (MDF) or as we call it here 'Customwood'. as this take track pins without too much effort.

Any thoughts or comments on the best system would be appreciated.


Jurgen Kleylein's picture

Spline is my choice

I would only use spline roadbed, because it is the easiest way to end up with smoothly flowing track.  There really is no problem laying it out over open grid if you have a track plan.  Just draw the gridwork over a copy of your plan and make note where the track crosses the grids, measure it in scale and use the measurement to mark your full size gridwork.  Mount your risers at the places you marked, and connect the risers with spline, sort of a connect the dots sort of thing.  The Spline with take care of the space in between the grids.

One problem you will run into, though, is that if you have a 12" grid, your drill may not fit between the joists to attach the risers.  You need to also take care to make sure your curves are constant radius; spline tends to create parabolas instead of circles.


HO Deutsche Bundesbahn circa 1970

Visit the HO Sudbury Division at www.wrmrc.ca

The preceding message may not conform to NMRA recommended practices.

all of the above

I use all methods on the same layout.  Plywood works best for yards, wide track area and towns.  Spline is good for single and double track.  Pins to hold the track in place are not a problem for me as I use caulk for this. 

Spline does take some effort to place properly and needs to be held in place horizontally. but it is a good base for really good looking trackwork.

Jurgen's method for placing spline is pretty close to what I use. 

I do not use MDF on a layout as I have found that, without a lot of support, it will sag.  3 ply and occasionally 4 ply plywood will sag as well so I avoid these as well


Jurgen Kleylein's picture

I use plywood for yards, too

Actually, Terry, you're right about plywood for yards.  Once you get to over 3 tracks wide, plywood is better just to keep things simple. 

I use dimensional 1-by lumber which is actually 3/4" high for the spline and 3/4" plywood most of the time, except in helices where I use 1/2" plywood to save space and reduce grades.  Keeping most of the roadbed the same thickness makes joining different sections together easier.


HO Deutsche Bundesbahn circa 1970

Visit the HO Sudbury Division at www.wrmrc.ca

The preceding message may not conform to NMRA recommended practices.

Roadbed Choices

For anything larger than the classic 4x8 layout spline roadbed is a good choice. However, I find it to be just a tad too fiddlie for me. One consideration is the need to turn those 4x8 sheets of masonite (hardboard) into 1" or 1 1/2" by 8' strips. A table saw is pretty much a necessity. I don't have one!

I experimented with MDF on my last layout and am using it exclusively on my new layout. I'm using a mix of L-girder and open grid benchwork with supports on nothing larger than 16" centers and I haven't had any problem with sagging at all.

However, I do cut my roadbed much wider than most people. I allow 2" on either side of the track centerline (on single track) and 2" on either side of two or more tracks on 2" centers. I do this for 2 reasons: 1) to give myself a place to attach my scenery to web and 2) to give me a solid base to mount my catenary poles. If I need a steep slope coming down right from the track (as in a fill) I simply cut the roadbed down as needed with a saber saw once it is in place.



"And the sons of Pullman porters and the sons of engineers, ride their father's magic carpet made of steel..."

Modeling the  Elk Creek Railroad in HO.





If you are going to handlay, hardboard spline really doesn't make that much sense, since you have to put something over it to spike into, If you are going to glue something on top of the spline, then that is really your surface and what you have underneath it doesn't matter.  Plywood is just as good.  If you are going to handlay and want spline, use Homasote spline.

A 12 inch grid is pretty tight, 16-24 inches is much easier to work with.

Easiest, just use 1/2 in ply in a cookie cutter.  You can have it done fairly quickly.  It will actually take longer to install the roadbed than that sub-roadbed.

I'm not a big fan of foam roadbed.  On a 12" grid, I don't see why you would need 1/2 ply under the foam, if any ply at all.

Regardless of roadbed I would suggest using latex caulk to apply your flex track, unless this is an extremely temporary railroad and you plan to pull it up in a short time.

Dave Husman

Modeling the Wilmington & Northern Branch in 1900-1905

Iron men and wooden cars.

Jurgen Kleylein's picture

don't need homasote

I handlay and spike right into pine spline; not a problem.  For plywood I use poplar ply and it spikes really well, too.


HO Deutsche Bundesbahn circa 1970

Visit the HO Sudbury Division at www.wrmrc.ca

The preceding message may not conform to NMRA recommended practices.

cv_acr's picture

Spline Types

A lot of current articles and postings promote using Masonite (hardboard) cut into 3/4" strips for making spline. I guess because it's already in a nice 1/8" thickness. Spiking into that would be pretty difficult/impossible.

Since you pretty much need a table saw to cut consistent 3/4" strips as well, just tighten the fence down to 3/16" and feed 1x4s through it. Spiking into pine is like spiking into warm butter and 1x4s are easier to get and handle than sheets of Homasote.

Greyhart's picture

Another Spline Material

I saw a blog post not long ago where the guy was using the material from drop ceiling panels for spline. It's half an inch thick, soft enough to cut with a sharp utility knife, and flexible enough for any curve you'd want a train to go around.

I'm planning to try it on my layout when I get to that step.


 Ken Biles

My First Model Railroad





dfandrews's picture

Ceiling tiles, spline, and plyw


I'm not so sure you gain any advantage making spline from ceiling tiles, and it may be unstable in the long term.  I am using ceiling tiles, back side up, on top of plywood, for yard, industrial, and other generally flat areas.  That way I can carve drainage ditches and other undulations to relieve the utter flatness.  But ceiling tiles, over time will sag, even the best of them (I'm using armstrong 3/4" thick tiles).

For fixed radii curves, particularly in room corners, I cut a series of cookie-cutter sections from 3/4" 7 ply plywood. 

For a nicely sweeping S curve on a grade, I used spline, and am happy with the results.  I used masonite hardboard ripped with a radial arm saw in my driveway.  Ended up with a large pile of sawdust, but since I did two 4x8 sheets, I have a lifetime supply, and don't have to make sawdust again.

Here's a discussion about spline, the sub-hobby of C clamping, and the joys of glue flicking


Edit:  And I adhere cork roadbed to the masonite spline with adhesive caulk, then use the same adhesive caulk to either hand lay, or use flex track, or use CVT ties and rail.  It all works.


Rincon Pacific Rwy, 1960.  HO scale std. gauge - interchange with SP.


Roadbed Choices

Many thanks to all for your comments. However, I still confess to being a bit overwhelmed with the options.  Jurgen I like your idea of pine splines.  I have a good table saw so cutting timber, masonite or anything else is no real problem.  I also have access to large quantities of 1- by pine in very long lengths. Can you confirm the thickness of each spline (before laminating).  I am picking 3/16 or 1/4 but maybe even 5/16th would be OK?

I also plan to use 12mm ply for flat areas with multiple tracks such as fiddle yards.  But I am also thinking that wiring (it will be a DCC layout) should be a lot easier with splines.

I would appreciate a bit more detail on laying track with 'caulk'.  Being a Kiwi, American brand names aren't much use to me.  I presume the caulk is something that sets relatively quickly - if it doesn't how do you hold the flex track in place while it goes off?



Modelling CSX in HO

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