My On3 track plan is now complete; it's not very complicated and I've chosen to use less track (no spaghetti plan) to leave room for more structures and scenery. I'm getting close to starting actual construction and have decided to use spline roadbed. I used this many years ago and it was pretty successful on an HO layout. I've also used the "cookie cutter" method of cutting out pieces of plywood. This time I'm leaning toward using 1/4 inch hardboard (Masonite) ripped into one inch wide strips. There are a number of articles on the web (Google "spline roadbed"). I expect some of you have used spline roadbed on your layout(s). Any advice you may have from your experiences would be appreciated. I'm going to need to use homasote over the spline since I want to hand lay most track with code 83 rail (recycled HO Rail Craft flex track from my present layout). Did you put in your basic scenery before track laying?

Thanks

Paul S

Paul,
I would stay away from masonite for spline as it has a tendancy to expand or contract with changes in humidity. I would go with a thin plywood and glue the homasote to the spline. Just MHO.

Al

I have never used the spline technique, but I'm under the impression that it is usually the best.

I prefer to have all of my track in place and functioning before I add my scenery...just in case I have to make changes. This can allow you to solder from the top of the layout rather than underneath (I have many fond memories of molten solder landing on my skin while working under my old HO layout).

Michael

Paul,
I would also suggest staying away from any material prone to absorbing moisture. You can still use the cookie-cutter approach to transition into the grade and then go to the spline roadbed for the remainder of the elevated track.

One advantage of the spline roadbed is that it is very easy to get nice smooth transitions into your curves by taking advantage of the way the individual splines flex. If you think about it, spline is actually the cookie cutter method turned on its side to transition into curves (does that make sense?!).

I would save scenery for last also, although you could certainly install some of the plywood profile boards at this time (if using the cardboard strip/plaster gauze method).

Jim

There is some pretty good 5mm thick import plywood that is inexpensive, cuts well and is very stable. A number of my layouts in N and HO were cookie cutter which I really like....yet to build a entire layout with the spline method.

Thanks to all for your comments and suggestions. I understand and agree about using materials that can absorb moisture. Even plywood has a certain expansion although much less than dimensional lumber. My basement has an effective dehumidifier plus the house has air conditioning that lowers the humidity besides cooling the interior. (After Vietnam in 65-66, I have an aversion to high humidity). The basement is normally dry. I'm still inclined to use masonite strips because of the cost of wood but will build a mockup to test its on-edge strength.

I have not used homasote before and can get sheets locally at Menards. For those that have used it for roadbed, did you seal it and with what? Did you have any expansion/contraction problems with it? Since I'm using 40", 44" and 48" radius curves (On3), I believe I can rip the homasote into narrow strips that will bend around the curves. I'll have to test to find a width that will work without lots of breakage. This will also help me determine if I can put spacers between some of the masonite strips and still create a strong and stable roadbed.

Paul S

Paul,
Homosote will expand and contract with the change in seasons unless well bonded to a stable base and sealed. This is one more reason why pine is the preferred spine material. If cost is a big factor, then regular roadbed cut from 1/2" plywood might be better than spline for your purposes.

I cheated once on a 2-rail layout by not providing a good base for the homosote and by waiting too long to ballast my track. I paid the price with rail gaps that would open in summer and numerous kinks in winter, particularly after sub-zero nights when the furnace ran constantly drying out the air. Ballasted track is more stable from season to season as the extra bond tends to prevent movement, but you still need a good base under the Homosote.

Homosote can be sealed with regular flat latex house paint.

You can always cut some saw kerfs in the homosote to aid in bending. They will be hidden later by your ballast.

Jim

Paul- Spline is the way to go. U se a playner (rent one) to get a smooth surface. I do no favour homosote so I use 3/8 inch cork for the roadbed. All wood working is held to-gether with white or carpenters glue and screws...nothing ever has shifted on me and no problems with the weather.

You need to borrow lots of clamps from your friends to do this properly....have fun and don't spare the glue...

A progress report: I spent most of yesterday cutting and gluing one inch splines of 1/4 inch masonite. Since I'm not ready to build roadbed on the railroad, I glued up several strips around a 40 inch radius fixture mounted on an old solid door. This worked reasonably well until the glued pair got very long. During an attempt to move it, its unsupported weight caused the spline to twist and break at one of the lap joints. I would not have this problem if the spline had been installed in position on the railroad. It does take many clamps to glue the splines together.

I experimented with a new "pin nailer" gun I bought for Father's Day. It shoots 23 gauge pins (headless nails). These are approximately the diameter of a straight pin and are normally used for finishing work on cabinets since they leave a very tiny hole that is easy to disguise. I attached wooden spacer blocks along the central spline with glue and one inch long pins. The pins held the blocks in position (surprisingly well) while the glue dried. Today I'll glue another pair of splines to these blocks to form a four inch wide roadbed.

Masonite is easy to work with but I'm not completely convinced that it's the best material for my application. I will investigate the cost of using 1/4 inch plywood instead. There are many levels of quality; some of the best (many layers and no voids) I've used in cabinet work is imported and is very expensive. Cheap luan plywood is of poor quality and makes lots of nasty splinters when you rip it because of the very soft wood.

More later....

Paul S

Paul,
It sounds like your layout is off to a fine start. I'm looking forward to seeing pictures of your bench work!

Michael

According to John Allens Book he did basic scenery and then laid his track.

DC Sr

DC Sr, there are actually some of his slides which show finished scenery but no track! Definitely my favorite modeler of all time.

Michael

I looked at various types of 1/4 plywood this weekend and came home with a sheet of five-ply underlayment that is 6 mm thick. It's more expensive than masonite and most other grades of plywood but has no voids and is smooth on both sides. I've calculated I should be able to get 38 strips from a 4' x 8' sheet. A four spline design with spacer blocks (on six inch centers), will yield about 76 linear feet at a cost of $.40/foot; if I use a six spline design, this will yield 50 linear feet at $.60/foot. The splines will be slightly over one inch wide. My benchwork has risers on 16 inch centers so I think four splines should be adequate for MMI On3 locomotives (they are pretty heavy).

I'll start ripping splines and make another test section before I decide which material I'll use but at this moment I'm strongly leaning toward this underlayment plywood. I've used a similar product for drawer bottoms and it's stable, light and strong.

A spline using spacer blocks will need a top on which to glue the ties. I may use plywood for this as well but perhaps a cheaper grade. I plan to experiment with slightly tapered pieces that when laid side-by-side, will go around the curve. A problem with this design may be it will be noisy but I'm not sure if this will be objectionable or not since my engines have sound anyway. I could use cork roadbed as I did on my HO layout. However, a lot of narrow gauge track in Colorado appear to have little ballast depth unlike mainline, class railroads. So I prefer a "flat" roadbed for appearance with minimal ballast (but enough to stabilize the track).

When I get further along in this project, I'll post some photos.

More later...

Paul S

Here are some progress shots on the masonite spline roadbed experiment. The last photo is a closeup of the pin strip used in my pin nailer. These are only 1/4 inch long...they are about the same diameter as the straight pin. The nailer can use various lengths up to 1-3/8 inch long.




More info about using the 5-ply underlayment strips later.

Paul S

Very professional looking spline!

If you purchase foam sheets, you can cut it square so as not to produce a profile...or just install foam strips inside out so that it lacks the visible profile.

My layout is cork on foam on plywood...it is nearly silent except when the wheels clink over frogs/gaps in the rail.

EDIT:
Here is a picture of it...

My bench work is very light weight...it isn't intended to be permanent, but I've tested a few different roadbed types with it.

Michael

Michael,

Thanks for the photo of your layout construction. I glued up some of the 5-ply splines last night. The resulting roadbed was very strong and I'm changing my design because of that fact. I don't need that much strength...I'm not planning on standing on it. Therefore, my latest thinking is I will only need two splines with 2 inch spacer blocks to create a 2 1/2 wide roadbed (ten scale feet) skinned with a 1/4 inch ply top. This will be lighter (and cheaper), more rigid and stronger than a "cookie cutter" roadbed of 1/2 inch plywood.

Five-ply underlayment is surprisingly stiff in one inch wide splines. Bending it on sharper than 40 inch radius curves requires strong benchwork and may not be practical for most model railroad benchwork construction. (A thinner width would be easier to bend but less strong.) I've been bending the splines in a jig screwed to an old, solid core door I normally use as a temporary bench for woodworking projects. Masonite is much easier to curve but not as strong. Fewer ply grades of plywood should also be easier to bend. It's a compromise between strength and pliability. Five-ply surprised me with its stiffness but also impressed me with its strength. Since 40 inch curves will my minimum, I'm planning on using five-ply after I refine my design and fabrication techniques. I'll need to add temporary, diagonal braces to my risers on curves. Once the splines are skinned with the 1/4 inch top, the curvature is locked in and the lateral stress is removed from the risers.

I'll consider yours and others suggestions in my final design. I'll need to build a test track to run my equipment to test its noise characteristics. I'll post more photos later.

Paul S

Paul,
Been following this thread with a great deal of interest as I am curious about how it works out. It looks like you could do prefab sections and install them as you go or later. I would suggest you use homasote glued on top of the plywood for sound repression and ease of driving spikes or use of nails on flex track. You could lay your prefabbed sections on the homasote and mark your homasote with a pencil. You would need to overlape the homasote sections to prevent the joint from showing. Just my idea and if you wish to call me and cuss me out, feel free to do so. Keep up the good work.
Al

I made more progress today using a two-spline design with a 1/4 inch plywood top. It worked nicely and is strong. I used a pair of five-ply splines with a two inch spacer block every six inches. Gluing and nailing 3/4 inch brads (with a brad nailer) made assembly quick on my temporary fixture. Cutting the top "skins" was a little slower due to all the angles. I ripped scrap pieces of 1/4 ply into three inch wide strips and them cut the end angles with my chop saw. Once these were glued to the splines and spacer blocks, the curvature was locked in place. I then used a router to flush trim the top even with the splines.

Photo one shows the roadbed before trimming. Photo two shows the roadbed after trimming and a brief sanding. Photo three shows the underside...simple and easy construction that is both light and strong. Last are two photos with a piece of flex track and a pair of AMS box cars and a San Juan caboose. The 40 inch radius makes the cars look nice on the curve.

I still need to experiment using this design with switches. Two inch clearance between the splines will let me use Tortoise switch machines (they are 1 1/2 inch wide). I have many from my HO layout.

Al, I probably could build sections of track in the shop and then install them on the railroad. But I expect to build the spline roadbed in place to ensure everything fits. Once the roadbed is glued, it has little "wiggle room" to make up for any measurement or construction errors. I make plenty of mistakes so I need to eliminate as many opportunities as I can. I have a sheet of homasote that I plan to experiment with...I've never used it before. I think homasote has been used on layouts for decades. I'm sure it will have a good sound-deadening effect.

This project has been fun, educational and has gotten me excited about getting started on the Puma Creek Branch. I'm certain there will be many challenges ahead and I look forward to solving them.

Paul S

Paul,
Those cars sure look nice on those large curves. Your carpenter work looks good as well.
Al

Adventures in homasote:

Yesterday I started working with my sheet of homasote. Wow, is that stuff dusty when you cut it with a circular saw! I'll need to fabricate some type of dust collection hood; I have dust collection on the table saw and band saw. Despite the mess, I was successful in ripping several one-inch wide strips. I was pleased to discover they will bend around a 40-inch radius curve without breaking. I then spent a couple hours building a jig for my band saw to rip a tapered profile that is close to a 1:2 slope (a standard profile for SP roadbed).





I fed a long strip into the jig and through the blade to cut the profile...it worked well. I then put four strips together to make the roadbed. I'm pleased with its appearance.



I then took a piece of my masonite spline and added a four-inch wide plywood top. I scribed a centerline down the plywood and glued the homasote strips with yellow glue. I held the strips in place with 3/4 inch brads driven with my brad nailer. After a light sanding, I placed a piece of flex track on it and made the following photo. The long slopes of the roadbed will be handy to attach scenery. More later...

Paul S

My biggest complaint cutting homasote is the dust it produces. I built a dust collection hood for my saw. It is held in position with two rare earth magnets on the saw's metal sole plate. I insert a hose from my dust collector into the circular opening...it captures almost all of the dust if I don't saw too quickly. This saw is an antique; it belonged to my grandfather who bought it in the 1950s. Its die cast housing makes it twice as heavy as a modern saw...they don't make them like this anymore!



This is my set up for ripping splines. I use an aluminum guide and set its position with a guide stick. C-clamps hold the guide in position for the cut. I use a sheet of styrofoam insulation under the plywood/homasote/masonite to support the cut off piece. Once the length of the guide stick is determined, you can rip uniform strips easily and quickly. A new, fine tooth blade (40 teeth) will cut a nice edge without lots of splinters.



I apologize for taking up band width on a subject that might seem so off topic. But, there might be someone just starting their first layout and perhaps this will be useful to them.

Paul S

quote:

they don't make them like this anymore!

Sure they do!

Management has given the okay to proceed with construction of the Puma Creek Branch. Track workers have successfully completed the first part that will be cantilevered over my workbench. I drew a full size track diagram on scrap cardboard to check my measurements before I committed it to wood. I used the spline method I discussed earlier.

This section connects the under-layout reverse loop (the left side) to the layover tracks (the right, inside curve) and the track climbing up to the layout (the right, outside curve). Three custom switches will be built to connect these tracks together. The curves on the left are 40 and 44 inch radius. The right, inside curves (2) are about 38.5 inches and the outside curve is 40 inches. The overall width of this part is nine feet.



Here is the underside of the roadbed showing the splines and spacer blocks. The top is 1/4 inch plywood, glued and nailed to the splines and blocks. This makes a light but strong structure. "Cookie cutting" a sheet of plywood would have been easier and faster for this section but not as much fun.



This part will be overlaid with homasote and will have sides to prevent any costly accidents in case of derailments, etc. I'm going to start on the switches next. When these are finished, I'll post more pictures.

Paul S.

Looking good Paul. I am sure this thread will be helpful to others, no need to apologize.

Al