module construction

Discussion in 'Modular Layout Forum' started by inkaneer, Nov 1, 2006.

  1. inkaneer

    inkaneer Member

    As I get older I find that module weight becomes more and more of a factor in determining which modules to bring to a set up. We got a four foot module that has exquisite modeling on it and is a real hit at the shows. Unfortunately it is way over built and weighs a ton. So it is not the first one we grab when we go to a show and most of the time it gets left behind. We have embarked on a campaign to build modules light and strong versus heavy and strong. Also we are going to a six foot module to reduce the number of joiner tracks. The additional 2 feet of module will add some weight but six foot modules gernerally require two people anyway due to their bulk. Lacking any of the tools needed to process plywood into dimensional lumber we have elected to go with an outer frame of 1X4's with interior supports made from 1X2's. The frame is covered with 1/4" underlayment. Placement of the interior supports is critical to prevent the roadbed from sagging. The first interior support is placed 6 inches from each end to prevent the "ski jump" at the end of the module. Then annother 1X2 is placed every foot. In addition to saving weight the use of 1X2's allows the wiring harness to be stapled to the underside of the supports rather than having to drill holes through the supports. All pieces are sealed before assembly and then fastened together using screws only. No glue is used. This allows relatively easy repair of a module should it warp or rack. Scenery is made from extruded foam and use of plaster is verbotten. We did allow a limited use of Scultamold but lately have been advocating the use of a lite weight spackling compound. We like the new modules with the weight reduction.
  2. MasonJar

    MasonJar It's not rocket surgery

    Cool... got any pictures? Do you have a weight on the newly constructed 6-footers? Did you add styrofoam to the 1/4" ply decking? My experience is that 2" foam is strong enough (especially with cross braces on 12" centres) to not need a plywood deck.

    Glad it worked out for you!

  3. LoudMusic

    LoudMusic Member

    Very interesting. I too would like to see photos of your work. The use of 1x2 for inner supports makes me wonder if I should do the same for my future layout.
  4. Isambard

    Isambard Member

    What materials are used for "underlayment" and for sealing (against humidity?)?

    It would be interesting to see a photo of the construction.
  5. inkaneer

    inkaneer Member

    Unfortunately I am unable to post photos. We have kept the 1/4 inch luan underlay plywood rather than go to all foam as the plywood adds rigidity to the frame and helps prevent racking. Also we preferr the plwood for gluing cork roadbed and the sound is preferable with it. Also 2" foam was not originally available in our area. We did experiment with 3/4 and 1 inch foam but the plywood won out. As for sealing the wood we used just a coat of good white primer.
  6. railwaybob

    railwaybob Member

    Hello Inkaneer. The use of 1"x 4" for the frame and 1"x 2" for some cross bracing is a very good choice, particularly if it's pine. I would suggest that you might want to take a look at the number of 1"x 2" cross braces and how you place them. By my calculations, you've got six 1"x 2" cross braces whereas, if you used some styrofoam as a base, you could get away with two or three cross braces at most.

    If you don't like the "knotty look" of knotty pine, here's an old carpenter's trick to stop the knots from bleeding. Using a propane torch, lightly singe each knot until the pine sap starts to boil. Continue boiling off the pine sap. Repeat the process on the other side of the knot. This process will blacken the board but will be covered when you paint the wood. Wipe the burned knot and the wood with a cloth soaked in paint thinner, varsol, etc.

    As for using screws but not using wood glue, I would suggest you might want to try the opposite. All the screws do, if you've applied enough glue to the joint when fastening the pieces together, is to keep the pieces of wood in place until the glue dries. Once the glue dries (after 3 - 4 day), you can remove the screws. As a test, glue two pieces together to make a V using screws to hold them in place. Let the glue dry for a week. Then remove the screws and stand on top of the V. If the V doesn't collapse, very carefully jump up and down on the V (the reason I use the word "carefully" is so that you don't get hurt). If the V snaps apart, look at the break. You will find that the glue joint didn't fail. You will find that one side of the wood tore apart from the glue joint. The wood on each side of the glue joint is still intact. However, given the weight of the screws, I'd leave them in place.

    As for stapling wires, why not try DCC? All it takes is two 14 AWG wires and a 6-wire telephone cable. It's very easy to drill two holes into the cross pieces and router out a goove in the middle of the cross piece.

    The key to stopping any wood from warping is to coat all exposed surfaces with several coats of paint. If you are really finicky, thin your first coat of paint by 25% and apply it to all surfaces. This will allow the paint to soak into the pores of the wood. Then apply two more coats of paint to all surfaces. Do this before you install your styrofoam or before you start scenicking your plywood deck.

    The key to using styrofoam is to make it an integral part of the module. You can do this by using a polyurethane glue. "Dry fit" the styrofoam into the module frame to make sure it fits properly. You are looking for a slight "friction fit". Remove the styrofoam and "butter" the edges of the styrofoam with polyurethane glue. Also butter those 1"x 2" cross braces (the 2" side should be making contact with the styrofoam) and corner gussets (if you are using screw-in legs).

    Then wet the glue with a spritzer bottle, insert the styrofoam into the module frame and keep an eye on its alignment for the next hour until the glue sets up. Let is stand for 24 hours. Trim, sand, cut any of the glue that is out of place. Paint the top of the styrofoam deck with a flat latex paint. Add scenery.

    As for scenery, I cut out blocks of styrofoam, glue them onto the module using polyurethane glue and then finish sculpting with ready-mixed spachling compound.

    You end up with a nice, light module.
  7. CCT70

    CCT70 Member

    All GREAT advice, I'll bookmark this thread, thanks.

    Hey Mason, can we make this last post a sticky?
  8. MasonJar

    MasonJar It's not rocket surgery


    Unfortunately, there is no way to make a single post sticky. You have bookmarked the thread, but there are a few other ways to keep track of it:

    - You can bookmark in individual post by first clicking on the post number (e.g. #7) in the top right corner of the post. This will display the post on its own. You can then bookmark it in the usual way.

    - You can subscribe to the thread by clicking "sbuscribe" under the "Thread Tools" menu, which is in the light blue bar at the top of the thread. This will show up in your list of subscribed threads in your "User CP" (Control Panel), which is accessed via the light blue bar at the very top of each page. If you have elected to receive emails, you will get a notification if someone adds a post to the thread.

    You may also want to visit RailwayBob's excellent website ( which has a detailed write-up with lots of pictures on this construction method. There are a few updates needed (notably the recommendation of polyurethane glue over yellow carpetners glue), but it gives lots of tips on how to get measurements right, and what order to do things. It is an excellent method - I have built modules in Bob's basement with his guidance :cool:.

  9. W5SO

    W5SO New Member

    Dumb question - I have Lowe's and Home Depot in my area. Neither appears to stock 2" blue foam. Perhaps I missed it. Does it have a brand name? Where should I look for it?
    Thanks - Steve
  10. MasonJar

    MasonJar It's not rocket surgery


    Welcome to The Gauge!

    What is "your area"? If southern California, you may have some difficulty! ;) Cel-fort is the name that is printed on the pink stuff here (eastern Ontario, Canada). Don't see the blue stuff much.

  11. Jim Krause

    Jim Krause Active Member

    Sounds like a good plan to me. I hate to see people talking about 2X4's and a lot of other dimensional lumber and 3/4 inch plywood bases, especially on modules. I can also understand the restriction on plaster for module use.
  12. W5SO

    W5SO New Member

    Foam Board

    Thanks! finally found it under Dow Styrofoam and OwensCorning
    Dow is the blue stuff "extruded polystyrene foamboard." My Lowe's only has the 1/2" width. Continue looking for the 2" model...
  13. railwaybob

    railwaybob Member

    If you are looking for 2" styrofoam, you need to go to a building supply store where the home builders and commercial building contractors shop. Home Depot usually carries the stuff in sizes up to 1½" - 2".

    Make sure it is "extruded polystyrene" and not the white "bead board". Technically, Styrofoam is the trade name used by Dow. Cel-Fortex is the trade name used on the pink stuff. You can usually find it in blue, pink or green, depending on who the manufacturer is. It's all the same stuff.

    You can usually find it in two styles - butt edge and ship-lap. Butt edge, as the name implies, is simply a rectangular piece of styrofoam - eg 2"x 2'x 8'. The edges on the ship-lap style allow half of the thickness to overlap on the next piece by about 1" to make for a better insulated fit (after all, the stuff is really an insulating material). Retail stores like Home Depot usually carry the ship-lap style, although, if you enquire, they also have the butt edge style hidden out in the back of the lumber yard.
  14. W5SO

    W5SO New Member

    Thanks! I need to find a Yellow Pages...I guess they still print them.
    How come I cannot pull up your web site
  15. railwaybob

    railwaybob Member

    Just discovered my website is down. I have to contact my web host to see what happened.
  16. rfmicro

    rfmicro Member

    Modular weight reduction means different things to different folks. To me, weight reduction is critical as I get older. I have taken the tact of using plywood ripped to dimensional sizes 0.25" X 3" using a circular saw. Not the prettiest of cuts but still functional. These serve as the basic frmework of the module to include cross braces every two feet. The top of the module uses 0.125 ' X length and width of the module covered with either 2" of 1" foam. Additional foam will be used to form terrain using the base foam as the starting position or to form the bottom of lakes/ponds and the like. The legs will be made of 2" X 2" fitted with folding brackets and the feet with either levelers or locking wheel fittings. The wood, foam and nails come from standard stock locally. Hardware comes from Lee Valley Tools (brackets) and some other internet vendors (alignment pins, T-nuts and bolts). Can I stand on it - No, but then I did not build to that standard. Can I move the modules easily - Yes with locking wheels. Other than that, the modules are 2-man lift.

    I have strayed off the reservation regarding benchwork design and construction, but then this method meets my requirements. I have looked at so many layouts that are literly fortified with large dimensional lumber. I'm sure much of that is build by example(s) and the dimensional lumber was all that was available. I'm sure that were I to build a more permanent layout, the benchwork would probably be much different and a lot more use of dimensional lumber would be of use.

    I have tried to make the module(s) as light as possible. Only time will tell if I have made the right choice - and there's not a lot of time left.

    Trent Mulkern
    Mechanicsville, MD
  17. railwaybob

    railwaybob Member

    Hello Trent. You might want to take a look at my website for some tips and tricks on making very light-weight modules that weigh no more than 10 pounds each for a 24"x 48" module.

    My circular saw has been retired for a couple of years now as I use the saw service offered by Home Depot, Rona (a Canadian chain), and other building supply stores. They can cut the material faster and more accurately than I ever could. Two weeks ago, I picked up some 1"x 4" knotty pine at Rona, walked over to their saw service, and left 20 minutes later with enough material cut to size for two 30"x 48" modules. Last week, I picked up two sheets of ½" plywood from the cull bin at Home Depot which they cut into 6 pieces of 28"x 34" (with enough scrap left over for two more pieces) for another project I'm doing - all for the price (lumber and saw cuts) of $10 per sheet.

    If you're looking ways to further reduce the module weight, you might want to take a look at this part of my website for fabricating your legs.
    You can add a considerable amount of weight to the module if you go the route of fold-up legs. Going the route of the T-nut, a threaded bolt, and 2"x 2X leg can save you a lot of time and trouble both in construction and in assembly.

    In the past, we have tended to "overbuild" our benchwork by using such materials as ½"plywood and 2"x 4" (yup, I've seen 2"x 4" used as recently as a month ago). With the advent of lighter materials such as styrofoam, we are still overbuilding the benchwork and, in some cases underbuilding in our use of styrofoam.

    IMHO, for modules, all you need is a 1"x 4" module frame with one (at most two) cross brace in the centre (the cross brace is inserted with the 2" side facing up). The main purpose of the module frame is to hold the styrofoam in place and to have something to fasten the legs to. The layout is built on the styrofoam. Depending on the scale you are in (N-scale, HO, G-scale), the thickness of the styrofoam can vary from 1" - 1½" to 4". I tend to stay away from both extremes (the 1" and the 4") and have been using 1½" and 2" styrofoam with one cross member for HO scale and two cross-members for G-scale.

    Nothing has moved so far.

    At our recent model railroad show, a modular group brought in their modules. It took two of them on each end to carry the modules in - ¾" plywood for the deck, 1"x 6" module frame, 2"x 4" foldup legs, and 2"x 2" cross bracing every 12". Another module group was using 24" doors but with the steel fold-up legs. At the end of the two-day show, they had to lug these modules back out across the parking lot to their vehicles using carts and dollies.

    In the meantime, my friend carried his two 30"x 48" modules out to his car by himself (I carried the legs).

    Bob M.
  18. rfmicro

    rfmicro Member

    Hi Bob M,

    I appreciate the guidance. I had seen your web site and module production site before in my lurking on varous RR forums. I am using your guidance plus some others to come up with a module fabrication scheme. Regretfully, I do not live in a country that will cut lumber to your specs. I can barely convince a store worker to assist in loading lumber into the car much less even cutting a 4' X 8' in half. All the Lowe's in our area have their saws inoperative - all at the same time. That's a subject that I will leave for another time.

    Where we differ is that I have selected to go with plywood cut into 3" strips vs 1" X 4" dimensional lumber. The latter would be easier to work with but adds to the weight. The former don't look pretty, but then that is what facia is for - hide all the little mistakes. I have also elected to wait on the alignment pins until I have several modules to connect together. I also won't lay the track until I have the modules aligned and level to insure I have perfect alignment. The modules were never intended to attend shows or mate with other's modules. So conforming to a NMRA/FreeMo standard was not in my plans. As the number of folks that are into model RR here locally can be counted on one hand, I was planning to build my layout to suit me.

    Wiring, Digitrax LocoNet plates, etc were also delayed until I finish the track layout. The base-line plan of this layout is to have it mobile for perhaps one last move and to be able to work on each module section removed from the module. There will be three separate levels connected with a helix between levels for the vertical plane and then each module connecting in the horizontal plane.

    I have also gone with a 1/8" plywood base under the foam with 1" X 3" plywood cross members for support. I also held off on any carrying alignment pins until I see what the scenery height will end up. I am also going to use folding leg brackets on the 2" X 2" legs for portability. Removable Leg cross braces also apply. I haven't completely settled on leg levelers vs rollers with locking nuts. I am leaning towards the latter to act for both portability as well as a leveling device.

    Once I complete two of the ten modules planned, I will see if this concept flys or not.

    Thankyou again,

  19. railwaybob

    railwaybob Member

    Hello Trent. Always remember. The railway is yours. You're the boss who can do whatever you feel like doing. You only have to answer to one person - you.

    Have fun. (I am!)

    Bob M.
  20. rfmicro

    rfmicro Member

    Hi Bob, You are of course correct, but I truly enjoy reading the advice and Photos posted. There is such a wealth of knowledge here that I always come away with a golden nugget of information that will help me.


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