Construction of the Lassen & North Coast Railroad began in earnest with the construction of the three box frames for the layout.
The L&NC is intended to be a portable layout consisting of three modules that will individually fit into the back of a small to mid-sized vehicle, including crating material. All three modules should fit into a larger vehicle, such as an SUV or Van. To do this, I’m building a foundation that—for lack of a better term—I call a “box frame.”
Most benchwork is done in the L-girder style if the layout is permanent or in a box style if portable or modular. I’m building a variation on the box theme, so that it can be both portable and include two levels. Each module consists of an upper and lower frame, joined together at four corner posts. Both top and bottom frames are topped with a piece of 1/4″ plywood. This approach should help keep weight down while making the structure rigid.
The trick for this layout, of course, is to get three two-level modules to fit together securely so they can be taken apart for work or for transport, then put back together again reliably. One level is easy enough, but two levels?
Building A Stable Foundation
I decided that the way to pull this off was to prepare the necessary lumber for all modules at the same time, then put everything together at once to guarantee fit. I chose poplar from my local Lowes instead of pine. While more expensive, poplar more than makes up for it with its straight grain and hardwood strength. For joinery I decided on lap joints; more glue surface and thus more strength than simple butt joints, but easy to do. I like to follow Norm Abram’s methods and pin all joints with brads during glue-up.
My small collection of shop tools made this part easy. I cut all the pieces to length on the miter saw, using stop blocks to cut multiple pieces of the same size. Most frame members are made from 1 x 2’s; I used 2 x 2 poplar for the corner posts. Then I taped frame members of the same size and type together (see the image above) and, with a dado blade in the table saw, cut the lap joints at the ends, and dadoes for cross members, in the frame members. Then, at a small bench-top drill press, I cut holes in pieces intended to be used as internal cross members to facilitate wiring and other needs.
The last piece of preparation was on frame members of adjoining modules; these connect to each other when the layout is assembled. Preparation of these pieces required the installation of an alignment system that guarantees the layout comes back together consistently.
I use alignment pins from McMaster-Carr for aligning adjoining modules, choosing the 3/8″ diameter pins and matching liners. The fit of the pin into the liner is precise, and will bind if you attempt to force them together at the wrong angle. On the other hand, the rounded ends of the pins help guide insertion which, if the angle is correct, is smooth as silk.
I configured four pairs (two pair for each module interface) of frame members to butt against each other with the pins for alignment. Each pair was taped together, I marked center points and then drilled and countersunk on the drill press. Actually, I countersunk first on both sides of the taped pair, then drilled the smaller through-bore. I use Forstner bits for this kind of thing, because of ease of centering and the clean bores those bits produce.
After gluing up the top and bottom frames of the first module, I set the corner posts that were dadoed to fit into the frame corners. As you can see, the posts form short legs for the module in addition to supporting the top frame.
For the top joint, I created an ersatz mortise and tenon joint to hold the top when installed. To do that I set the top frame on top of the posts, then glued blocks to the frame around the “tenon” to form the mortise. The mortise and tenon joint created is snug; This joint is intended to come apart, so I eased the top edges of the tenons to make assembly/disassembly easier.
Here is the fully assembled first module.The near end abuts the next module; the matching member for the lower box is mated with the assembled module to test fit.
Next the middle and right hand modules were built, then the whole thing was put together to test fit and the alignment system. Thanks to the McMaster-Carr alignment pins, and careful assembly making sure everything was aligned correctly every step of the way, the frames came together correctly the first time! I can’t emphasis enough how important it is to take your time, constantly testing and retesting fit of key components, when doing this kind of framing.
At this point the western (or right hand) module is only partially framed. When I put together the helix intended for that section, I found I needed to make a few modifications to the upper frame to make it work. I’ll get into that in a subsequent post.
In the meantime, the last step in basic construction was to create a fastening system to hold the modules together when assembled. NTrak and other modular systems generally rely on C clamps. On this layout, given its design intention to sit on top of a bar (or tables), C clamps are a bit awkward. So I chose 3″ machine screws that connect with 4 prong tee nuts (often used in furniture making). After clamping each connecting pair of posts together, I drilled the hole then set the tee nut on one side to connect with the bolt inserted from the other side.
The modules fit together well enough that it is not generally necessary to use the bolts to pull modules together. The bolts with the alignment pins make a solid connection that can be assembled and disassembled easily.
With the basic frames complete I topped the eastern (left hand) and center modules with plywood. I also put 1/4″ plywood atop the lower frame of the western module. The upper frame of the western module will need more work to accept a helix. That project, and general build up of the layout are ahead.
With much to do, I’ll pick this up again in a subsequent post.