I built my layout using the L-girder/joist plan and 2" blue foam. My suggestion is to use 2x2s as the joists (cross members), and space them no more than 12" apart. This will give you plenty of
surface area to glue your foam base to the benchwork. It also gives the foam plenty of support.
FRAMEWORK (Baseboards in the UK)
For a light and strong framework for your layout, build it out of thin sheet plywood.
Get a sheet of plywood, 4mm to 6mm thick and large enough for the top of your board and also get a sheet of the same plywood cut into strips about 4" (100mm) wide to use for the sub-base structure.
You might want to cut these strips yourself, but they do have to be dead straight and you might find it worth a cutting charge to get your wood supplier to do the cutting on his sawbench.
Cut the board top to size and lay it face down on a flat surface. Using the strips of ply, cut and tack glue the strips to the edges of the top so that you finish up with a shallow box structure. You
can use a quick setting wood glue or a hot glue gun (faster).
Now you have to build up a framework within the box, using the plywood strip, to make the whole assembly rigid. The internal strips should be about 12" (300mm) centres. First cut longitudinal strips
to fit as neatly as you can between the ends of the shallow box you have already made. The number of strips you require will depend on the width of your board - i.e. one strip for a two foot wide
board, two strips for a three foot wide board, etc.
Then cut the lateral strips to fit between the sides of the shallow box structure, the number depending on how many you can get in the length of the board at 12" (300mm) centres.
Don't glue any of them yet. Put the longitudinal strips in place and hold them temporarily in place using something like duct tape. Then place each lateral strip in its position on top of the
longitudinal ones and mark both the longitudinal and lateral strips where they cross. Remove all the strips and cut half joints at all the marked points
When all the half joints are cut, reassemble the interior strips again, and check that all the half joints fit reasonably well.
Next, you want to put a few diagonals in the box structures you have just built to prevent the assembly twisting. Three or four should be sufficient for a small to medium sized board (up to 6' x 4').
So cut and fit some ply strips to go across whatever number of diagonals you decide.
After that, take all the strips out and drill a lot of holes in them - a large diameter hole cutter on a power drill is ideal for the purpose. These holes allow for under baseboard wiring and they
also lighten the structure as well.
Once all this is done, reassemble all the pieces and tack glue them to the shallow box structure.
You've now got a potentially rigid structure, but the tack gluing is insufficient to give the rigidity. So you now reinforce every joint with glass fibre tape and resin. I found that mixing up 100cc
of resin at a time gave me sufficient mixture to do what I could in 20 minutes before the resin went off. Leave the board to set and you will finish up with a structure which is light and very
strong.
When doing the tack glaceing and glass fibre taping, lay the board on a flat surface so that you don't build in any warps during the glaceing process. You would be well advised to do the glass fibre
work out of doors, or in a large, well ventilated indoor area, since the fumes from the resin can cause discomfort. You should also take care when using glass fibre resin, and wear protective gloves
and eye protection, and get good advice on the application of the products.
PROs
This gives a very lightweight, rigid structure which is easily portable and uses cheap wood.
The level of carpentry skill required is quite low since joints need not be perfect as the glass fibre tape provides all the strength.
The only tools required are a saw, a square (to keep things square), a pencil, a glue gun and some duct tape. A tape measure is hardly necessary if the board top is to a readily available size of
plywood sheet.
CONs
The flat top of the structure is necessary for the overall rigidity. Therefore all scenery will have to be built up from the board top and it will be extremely difficult to arrange cutouts to allow
for terrain to go below the board top.
The thin ply sheet top provides a very good sounding board for train noise and you have to make good provision for sound insulating track underlay if you want to avoid noisy trains.
Glass fibre materials can be quite expensive and this tends to nullify the cost savings in using cheap plywood.
FUTURE POSSIBILITIES YET TO BE TESTED
Use the structure upside down and support the track base on risers attached to the cross members. This would allow much more flexibility in scenic design, but provision would have to be made for
under track access after the scenery has been put down.
Use gauze bandage and hard resin wood glue instead of the glass fibre tape and resin. This would cut down the cost and would mean working with less hazardous products.
Jim
I've still got all the open-grid L-girder framework from my last layout, and am planning to build the frame as though I were going to buiild open grid, and then just lay plywood on top of the 1x4's.
Any reason why I shouldn't do this? I hate to start from scratch when I already have all the leg sections from my last layout.
One foreseeable problem would be if there are inconsistancies in the open frame bench work. That is that all of the 1x4s are at the same height. As well as the floor being level. That is the problem I have here, every piece of furniture I have near a wall has a very noticable lean, out in to the centre of the room. (The sold mahogany china cabinet being one of the most noticable, If I dissapear from this NG for a while, it means the china cabinet came down, and I'm pinned under it.)
As long as they are close, there shouldn't be much problem, but it will introduce small grades. I don't know if this is going to be a real problem or not, just becareful that staging tracks are level. You don't want 'staged' cars rolling down thru switches.
A little creative shimming should be good for this.
-Scott-
Do what I did. Screw a carriage bolt into the end of each leg on the layout. Now you can adjust 'em and take the slope outta yer classification yard!
Scott Marriam
That works, But drilling a larger hole, and inserting a T-nut and carriage bolt works even better! :)
-Scott-
My layout is constructed on a chipboard base laid on timber frame. It's probably not perfectly flat, but it's close enough. If you can't see any grades, and your cars stay put in places where it matters, you'll be alright.
Seriously though, the only place I have any unintended grades is in the temporary fiddle yard where the supports are too far apart. Check your framework with a spirit level before fixing the plywood, and if any bits are noticeably off then add a thin shim to put it right.
Rob
The frames are supported by adjustable vertical legs that are bolted to leftover bathroom cabinets. Photos are below. One of the cabinets has a slide-out shelf (scrap plywood and a drawer slide) on top for storage or workspace. If you try this, I recommend either a pair of under-drawer slides or standard side-mount slides. Mine has only a single center-mount slide, and it wobbled from side to side until I put blocks under the front corners.
Here are photos showing the benchwork. Nothing fancy.
Michael
