I have heard about splin roadbed for decades but have never really understood how they are built. How do you keep the top level and flat? How is it fastened to the risers (or are they only used over a flat surface? Etc.
Bruce, you place your risers first, keeping in mind that their tops must support the splines at the level/grade you want. So, the risers have to be clamped or screwed to the joists/framework with some care to that detail…the grade.
After you have your risers situated, even temporarily with just clamps or screws, you need to drive a 3" wood screw vertically into the centerline atop your risers. You will leave at least a full inch showing above the top surface of the riser. It is these that will anchor your strips of MDF or whatever you use. They get removed later once the six plies’ glue has dried.
I went to a local builders’ supply and bought a single 4X8 sheet of 1/4" MDF. For $10 they ripped it along its length as many times as they could with strips cut 15/16" wide. I’ll bet 13/16 would have been just fine, and we might have gotten another two strips that way. With those strips, from one slab of MDF, I did my entire 70+ feet in six ply.
Okay, your risers are in place, about every 3’ ideally, and a screw is sticking out of the tops, centered on the centerline, with an inch or more of the screw showing, but enough buried in the riser to offer considerable lateral support. From there, pick up any two or three lengths of the spline material you are using. Using yellow wood glue, I slathered a bit in a snakey line along one or two sides of the MDF, smeared it to spread it, and then pressed the two or three lengths together, but keeping all ends staggered apart by about 5". Carry the ply over to the risers and place them atop the risers. Clamp the ply against one of the riser screws, and then work your way along to all risers on which this ply sits, clamping against the vertical screw. Did you think to buy about 10 clamps when you were getting your materials if you don’t already have them? They are about $6 apiece for ones of any qualit
I’m SO glad I used the “cookie cutter” method. [swg]
Marlon, the words undoubtedly add up to a lot of concepts and processes, and I am sure they make it all sound like a heck of a lot of bother for little gain. And it may be so when all is said and done. Honestly, though, after you have figured out how to get them in place and clamped, you quickly learn the shortcuts and efficiencies. I think I was only three days doing all 70+ feet of the roadbed, and that includes the clamping and drying time.
Crandell
Making spline is actually pretty simple.
You set up the risers in the proper positions, and drive a nail or screw in the centre temporarily to guide the spline.
The spline itself is cut into strips about 1/8-1/4" thick and 3/4" wide. Some people use hardboard (“Masonite”), at my club we cut 1x4 lumber into 1/4" thick strips and use that. Works quite well and the soft pine takes spikes easily when handlaying track.
Once you have your risers in, and a big pile of spline cut, you start laying out the spline. Use nails/screws in the top of the risers to guide the first piece, and start clamping and glueing the second piece to the first. You need lots of clamps.
Once the glue dries on the first two strips, it should hold its shape fairly well. Remove the guide nails and glue on the rest of the strips to get the roadbed to the right width (this will take several passes).
Once the roadbed is finished, drill and countersink a hole and drive a screw through the centre of the spline down into the riser to hold it down.
Level the top of the spline with a hand plane.
That’s it, you’re done. Time to lay track. Advantage is very smooth curves and no mucking around with laying out and cutting curves on plywood and scraps and wastage. All cutting of the spline is done quickly at one, although a table saw is a requirement.
Here’s a couple photos of the process at my club layout:
Initial layout mockup for locating curves and risers:
http://www.wrmrc.ca/construction57.html
http://www.wrmrc.ca/construction69.html
Risers and first spline:
http://www.wrmrc.ca/construction70.html
Gluing:
And just to answer specific questions directly:
Simplest description is that it is just thin strips of wood laminated together. The thin strips bend easy making it easy to lay out smooth curves, but once laminated together the whole thing is rock solid and will maintain its shape without warping or sagging.
Block plane.
Screw it down. Once complete, the spline will hold it’s own shape, but it is screwed down to the risers to fix position. Advantage to spline is that there does not need to be any surface whatsoever below, flat or otherwise. Risers can be attached to joists or crossmembers of open-grid benchwork with no top surface.
I’ll leave off with one more shot showing how smooth this technique makes your track:
You can see more spline glueing in the background yet. The advantage of spline is you can create very long stretches of track very quickly. It’s only the number of clamps that you have that will limit you. Basically, get what you think is probably overkill, then double that number and that’ll be pretty close to what you need.