For some time I have been struggling with designing a benchwork for my next layout. The term benchwork is a complete misnomer in this case. The requirements are probably close to what a lot of people need.
Size: intended for a 2.5 x 7ft layout
Portability: essential for storage and moving sithin the house
Weight: Manageable by a single adult, maybe one adult and a child
Access: easy access to the underside of the layout is essential.
The layout will be N scale. SO I pondered all of this and during the early hours of this morning I came up with something I think might work. Here is my thinking.
I do some work with lasers, and I have two optical benches. One, an older unit is made of cast iron and weighs, well about as much as a huge pile of anvils! It takes six adults to lift it. The other is much newer, it is 900mm x 1200mm (about 3x4ft) and I can lift it and move it around on my own with only a little difficulty! Not only that, it is stiff enough to be usuable even when it is only supported crudely. So I had a good look at it, it uses a single piece table top with a sub table which is a huge resin casting. On the underside of the sub table their is an array of ribs, in what is known as a torsion box arrangement.
So could we use a simple torsion box for modelling. As explained in the article above we need to use one material for stability reasons. So lets choose 6.5mm (1/4 inch ) marine ply. I wont use MDF because of the residual discharge of urea-formaldehyde from the glue.
The processing would best be done on a CNC router, they are pretty easy to find aorund the place and not expesive to buy time on. Most cabinet making shops use them these days.
I have limited space, the layout needs to be easily moved for other activites. Preferably hoisted up to the ceiling out of the way.
Even 2" EFI is not torsionally stiff on its own, put a 2 or 3kg weight on one corner and see what the diagonally opposite corner does as you lift!
It doesnt give me anywhere to put wiring, switch motors, and electronics under the layout
Sure, I dont want to make things complicated, but I think I have a set of constraints that are not met by ANY of the techniquese I have seen in the literature - and I don’t believe my contraints are unique!
I’ve built a couple of layouts in the size range you are disussing in what some have called “waffle” style. This is simply a 1/4" plywood top plate, 3" wide 1/4" plywood ends and sides, and 3" wide 1/4" plywood cross pieces every 12-18". The bottom plate is also 1/4" ply, but with “windows” cut between crosspieces to allow easy access for wiring, switch motors, etc. I’ve put them together with both hot glue and with woodworking glue.
Fast, cheap, easy, and reasonably stiff and light. The cutting was not super-precise, one simply uses glueing blocks to hold things together.
Since no one needs to stand on benchwork for a small layout, the load per square inch is low and torsional stiffness is more important. The waffle-style has worked well and is pretty rugged.
You’re STILL making things WAY too complex. 2.5x7 is no big deal to build: 1/2" ply, 2" foam, and a 1x3 box frame around the perimeter, and you’ve got everything you’ve described above, except for the price and time to build. I can get the materials I need, build the basic frame, and have track centerlines marked in under an hour, and for less than $50. Most of my Ntrak modules are built this way, and mine stretch for 38 feet. Most have successfully survived 20+ Ntrak meets without any problems.
And no need to construct (and pay for) a hoist to the ceiling. Foam and ply weigh basically nothing (I can carry four of my 2x4 Ntrak modules. That’s two of what you’re planning), so just up-end the layout and stick it in a corner. My modular legs are off the shelf 1" PVC components, and screw into floor flanges on the underside of the layout. They take about 28 seconds to install.
Let’s face it: little toy trains don’t weigh anything, and don’t realistically need any fancy bracing or constructi
Yes John, if you load the 2" foam unequally it could be forced to sag or twist. But only the slightest amount of care in construction and handling will eliminate this problem, and thus the need for a frame of any kind. Remember you are working to make a platform for N scale trains, not a performance of “Riverdance”.
If you plan to lift it out of the way, it should be light. I’m thinking 10 to 15 Kg max for the entire thing, trains, scenery and all. You don’t have any physical limitations that would prevent you from lifting that kind of weight, do you? I envision you just picking this thing up and either standing it in a corner, or perhaps setting it on a shelf placed high on the wall. No block and tackle necessary.
Of course this means that everything needs to be fastened down, or removed and stored when it comes time to move the layout.
People build modules, the size you are talking about, all the time. They transport them without destroying them. At only 30" wide, this is way easier than dealing with a full 4 x 8. If you are really worried about twisting, build a nice frame out of qualty 1 x 4’s. You’ll need three 8’ pieces for a frame and a couple center supports. Then top it with 1/2" plywood, and skip the foam. This will allow room underneath for switch machines and wiring. It might weigh 10 Kg, pushing the total closer to 20KG total.
I just keep thinking “hollow core door.” Just put some thin plywood/masonite/MDF/etc around the edge, that comes down far enough to hide wiring. That’ll add extra rigidity as well, but the door should be pretty rigid, to begin with. If the door’s not long enough, you could easily extend the framing out, and add a new top surface.
Honestly, I think a sheet of foam insulation, with light framing from thin plywood, and a few corner blocks would be very rigid. Cross bracing could easily be cut with a jig saw. Just cut notches half way though where they cross over, and the bracing should almost hold itself together.
For the record, both of my staging areas are made of foam core. The “deck” is two pieces laminated to one another, then just sides brought down, with a couple of cross pieces to hold the sides parrellel. They’re strong, and have no weight. I’m not suggesting you build your layout out of foam core, but it shows that a simple structure can be made rigid. I think you’re overthinking things, a little.
See, this is what I get for having bright ideas in the middle of the night.
I have just got back from a session with my mechanical engineer and materials engineer, of course this wasn’t the purpose of our meeting! But we did discuss it and we threw some numbers at one of our simulation packages. My 1/4" plywood design is, with the material removed, lighter than a flush panel door. And extremely strong. So we ran a simulation on 2.4mm (whatever that is in inches!) plywood grid and a 3.2mm (1/8" is it?) plywood top. Still much stronger than necessary, of course very light and more stable than 1/2 plywood on a 16" centres frame.
So we ran it again, this time using 4.8mm ( 3/16" I suppose) foam core for the torsion grid, still amazingly strong, but getting lighter and lighter. So, my original choice of materials was wrong. But the basic concept is proving to be quite valid.
Their is another twist to this. I dont have any serious woodworking equipment. But I have sub-contractors with CNC routers, a 4 axis CNC laser cutter and a host of other production machinery. The estimate is that we could buy a single 4x8 sheet of 3/16" marine ply and take a sheet of 4.8mm foam core out of the subbies stock. Routing the ply would take about 30 minutes, cutting and shaping the foam core on the laser table about 20 minutes. The offcut from the ply could be used for a simple frame around the outside ( routed with interlocking fingers to make assembly really easy ) with the ends being a ply-foamcore-ply sandwich from which the whole thing can be suspended.
Thanks for the critique folks, interseting input. The simulations on the computer were really illuminating.
Layouts built on foam core, as it turns out, are nto new. I have one in a book at home called something like the ‘n-pire railroad’ which is built on foamcore.
Now isnt that eerie! Very similar design - same basic concept - torsion box. I couldn’t understand why I hadn’t seen it done before, of course that one has features specific to its application and the construction methods available. But a nioce light weight, very stiff module I am sure.
Why re-invent the wheel? You are going to use N scale on an 18+ square foot layout. You want portablility, ease of wiring and the ability to be stored easily. All of these requirements are met EASILY with 2" foam with a 1" frame. All of your objections to using foam are easily addressable with tried and proven techniques.
Start with a frame of 1x4" lumber. Use 1x2" lumber screwed and glued to the 1x4". This creates a lip for the foam to rest on. Use additional 1x2" lumber to make cross pieces. For a 7’ length, 4 cross members equally spaced is more than enough for support. The foam nests into the frame, supported by the 1x2" lip. The crossmembers provide support across the width of the layout and also provide a solid surface to attach wire runs to. If you install the crossmembers flat instead of vertically, you will have a recessed area under the layout to protect the wiring. For additional protection, pick up an old refrigerator box from an appliance store, cut it to fit under the layout and staple it to the frame. Totally enclosed protection that is easy to remove for more wiring.
It is not likely that you would have a heavy weight restricted to a small area of the layout where torsional stiffness becomes a factor. While 2" foam itself is not torsionally stiff enough to support a heavy weight on one corner, with a simple frame as I described, it is strong enough to sit on without much deflection.
This construction will give you a very light layout. The frame provides a mounting area to attach lifting cables so the layout could be raised to clear an area in the room. It is light enough for one person to carry (maybe even one boy!), it can be tilted on edge for storage or for working under the layout.
As for mounting switch machines, it will depend on the machines you are going to use, but there is a method of using virtually any switch machine with a foam layout. Openings in the foam are easy to make, the machines can be moun
This has been an interesting and illuminating discussion. Firstly, my original propsal is in fact grossly overengineered. But engineers can never be accused of that, can they? Well, this was never intended to be the last word on how I would build a layout, but it has certainly given me a lot of new thoughts.
Foam, in one form or another is certainly a wonderful material. EFI make a great basis for railroad modelling and I have no doubt that I will continue to use it, but I am not sure that the 1x4/1x2 framing is going to satisfy me. But of course my criteria for stability are based on what I do every day, for a living, not on what I am prepared to accept for something sitting in my basement. The originators and developers of DCC were roundly criticised in their day for pentially ruining the hobyy. SOmetimes they still are! But if they hadn’t forged ahead where would we be?
All I can say is thank you to the three members of the forum who have contacted me about the possibility of purchasing layout tables made this way. I have, of course, replied personally. But for others who are interested, we are building three tables each of slightly different construction over the next week and I hope to see the results by the end of the week when I get to the workshops to have a good look.