I’m going to build a shelf layout in a bookcase. The dimensions of the shelf cavity are 78" x 15" x 12" high. I would like to minimize the base height - I was hoping 1" high. I would like the base to be lightweight so I can remove it for workbench work.
I was thinking of using 1/8" lauan plywood for the top, framing with 1" x 1/2" lengths of wood under the edges and sides. I would use triangular pieces of 3/4" wood in the corners for extra bracing. All glued and screwed.
I was thinking making the top with lauan could help with the weight; it was used in an April 20i9 MR article about lightweight benchwork.
I only have basic woodworking tools, but I figure I can have the wood cut at the lumber place, though I’m sure I could cut the framing and triangular pieces if necessary.
I’m hoping this would provide a pretty rigid base. Any thoughts or advice?
My thought is that what this really comes down to is how much will a 78" long piece of 1x1/2 flex with the weight of the materials on it when you need to transport the layout to a workbench. Assuming lightweight scenery (i.e. not making a slice of the rockies out of plaster), given the weight of what could stay on the layout while you move it, I would guess it would be fine. I would be sure to have plenty of cross members to the frame for you to fasten (and I would glue as well) the lauan down so that it doesn’t warp in the middle over time. Triangular pieces in the corners would not be necessary. The luaun will hold the frame square.
I have built a number of layouts to take to exhibitions here in the UK.
One of the problems with larger boards is moving them!
While moving a basic piece of wood 78" long around is OK, what happens when it is covered in delicate scenery, buildings, track and with wiring underneath that is guaranteed to snag on something>
I would suggest making a couple of boards that can be managed and manipulated when needed.
There are plenty of techniques to cross a baseboard joint with track, electrics and scenery.
Have a look at the Woodland Scenics Modurail system. It’s built entirely from foam (and worth considering) but the basic structure is easy to duplicate in thin wood. They designed an open top box which is closed off over the top with plaster cloth creating a box beam. Of interest are the drilled hardboard strips glued inside the mating ends secured by standard 1/4 bolts and wing nuts. I can attest to the ease of installing these clamps and their strength. Foam modules would be ideal for a bookcase location because the bookshelf provides structural support. The foam module(s) only need to be rigid enough to facilitate moving the modules unloaded by trains.
Two 3’x1.5’ modules fit your space. I’ve built an “upside down” foam module 6’ x 22" out of 1/2" foam, also using 2" x 1/2" foam stringers glued underneath, for my yard, so the flat side is uppermost and the box and clamping strips are underneath. Because it has no bottom it isn’t a closed box. Added rigidity is supplied by a 1/8" x 3" x 6’ hardboard fascia piece glued along the face and 8" x 1" x24" Woodland Scenic Profile Boards along the back edge, glued to the edge with 5" above the top and 2" below. Profile Board is corrugated with 1/2" slots and ridges so the 1/2" base sheet can be glued into a slot for added rigidity. The Profile Boards are also easy to dovetail at corners which adds rigidity.
Thin plywood or other sheet goods would easily make a similar and pretty strong U shaped girder structure for your location. The support could be built below or above the layout surface, or indeed be rabbetted in partway up the sided of the “box” which would be very rigid and facilitate raising the track on risers and creating scenery with plaster cloth or foam sheet. Fir bookshelf use the frame pieces would best fit above the flat base, the bookshelf gives the support needed for operations. &nb
For my around-the-walls layout I’m using shelving from Menard’s - I believe the maker is John Sterling. It comes in a variety of sizes; in your situation the 72" by 15-1/2" size would be closest, or you could use two of the 36" long ones (or get one 36" and one 48" and cut the 48" down so together they come out to 78". They’re only about 1/2" thick, but very strong and seem to not want to bend or warp at all. I usually use the white ones, since I’m going to put scenery over them.
I think your basic plan is sound, but a few thoughts:
1 - as others have mentioned, the 78" length may give you problems when moving. Two 39" halves would be a lot better. If you build precisely, you should have no need to physically connect the base halves or the track (only electrically - see #2). But building precisely will require making the cuts yourself - store cuts are going to be +/- 1/16" (if you’re lucky), and not precisely square. You can buy a reasonably good power mitre saw at the big box stores for under $150. Not professional grade, for sure, but with practice and care, it will do the job for you. I sold mine locally for about half what I paid for it after I was done with it.
2 - Suggest you up the framing lumber to 1x2, which is actually 3/4x1-1/2. Use the taller dimension as the height, (just a little taller than you had hoped), and drill at least 1/2" diameter holes for wiring to pass thru all interior framing peices before assembly. Use #1 pine, and pick and choose the nicer peices at the store. Connect the 2 halves electrically using an automotive trailer plug.
3 - I would agree, the triangle gussets would not be necessary.
Sounds like a fun project - we’re here to help as you go!
Aluminum angle or channel plus foam sheet is the simplest to build, the strongest and the lightest. I am going to add that aluminum structure to my shelf modules.
The biggest challenge with foam sheet is achieving sufficient rigidity. Some resort to using 2" foam. Some use wooden framing or sheet goods under or on top of the foam. Edge support is usually enough provided your foam sheet isn’t very wide. Under 2’ wide seems pretty rigid. Anything longer starts to get a bit springy.
If you’re placing the layout on top of a shelf then it only needs strength when you lift it off to move it.
Cement board as in the stuff used behind shower walls or the stuff they use to make exterior siding?
