I don't know what "Open Grid" is, or how it differs from L girder. Maybe it refers to butt joint frame construction. I don't understand why there are all those "open grid" choices and only one L-girder choice. I also don't understand why almost all the poll choices involve plywood. My first layout (now gone) was L girders with joists, risers and homasote roadbed. No plywood. I had a book by Lynn Wescott (sp?) and he was adamant that homosote didn't need plywood lining it underneath, and he was right. In my opinion, plywood is lame for benchwork. Were I to build another layout, I might do things differently but I still think I wouldn't use plywood in any central role. Part of the layout (the flatter part) was cookie cutter with homasote, and the rest was just open, with roadbed supported by risers. I used the cardboard strips and plaster bandage technique to fill in the scenery, which wasn't a very smart set of choices. I never got much of it scenicked; I'd definitely choose something smarter next time. If I were to do it again, I'd experiment with foam scenery in more places, especially in areas around bridges and tunnels, but I don't think I'd alter the basic method for supporting the track. If you're modeling grades and mountains, it's the best method.
Plywood under Homasote Open grid and butt joint frame are meant to be the same. Linn H. Westcott's book "How to build Model Railroad Benchwork" second edition says this about Homasote and Upson board: "In virtually all applications it (Homasote) must be supported by plywood subroadbed or a flat tabletop." Page 15. Certainly you are entitled to your opinion and I appreciate your experiences, but Linn Westcott's position as well as the position of many others is well documented in regard to Homasote and plywood. I personally have never seen a sheet of Homasote or Upson board in any lumber yard where I looked for it, so I rely upon the expertise and advise of other modelers for Homasote qualities. With regard to 3/4 5 ply plywood, Joe Daddy's experience is that it is a superior sub-roadbed for cork. MDF, particle board, chip board and 3 ply are not suitable from my experience, however, others have claimed success. My own personal success with plywood less than 3/4" has been problematic. I tried 1" & 2" foam and find 2" satisfactory for flat work, but it is almost as expensive as 3/4 plywood $18 vs $25 at my Home Depot and the plywood goes much further as I use 3" wide roadbed paths. Joe Daddy thanks you for responding to this poll.
I've used homasote and 1/2 inch OSB panels (Oriented Strand Board, sometimes referred to as wafer board by the guys at Home Depot or Lowe's, but always called OSB panels at the "real" lumber yards) with great success. I had trouble with 1/2 inch plywood--bowing and layers splitting apart over time. I used homasote alone in one of my helixes, but had to double the number of supports under the spiraling ramp (which was only 1 inch wide). On my other 3 helixes, I've used a 1.5 inch wide ramp made of homasote on OSB panel and only needed 8 supports (4 at the diagonals, and 4 on the sides) on 2 circular ones and 12 supports on the oval helix. When making the vertical supports for the helixes, I used the 1/2 inch OSB panels because that was what I had on hand. For anyone using this method of helix construction, I'd recommend going with 5/8 inch or 3/4 inch thick vertical supports and drilling guide holes for the securing screws, because the 1/2 inch OSB panel sometimes split as I drove screws through the subroadbed ramps into the top edges of the vertical supports in the center of many of the 1 inch wide steps on the Pekin Helix and some of 1.5 inch wide steps.
I use the "L-girder" method with risers and plywood sections of subroadbed. The sections are connected with plywood joints under where the two ends of sections abut eachother. On top of the subroadbed, I use 3/8 thick foam-core poster board, which you can get at any good art supply store. It comes in 4x8 foot sheets, is easy to cut and has good noise damping qualities. Also, if you are hand laying rail using spikes, the poster board is easy to press the spikes into and holds them in place just fine.
Well in the first edition, Linn has this to say on pg 46: "Years ago...we used plywood or other hard material for roadbed. We used spikes...to hold the track down, but if we tried to drive these fasteners into hard roadbed, they buckled. Along came Homasote. It provided a semihard surface that would hold but wouldn't bend spikes or nails, that absorbed some noise, and that was generally ideal for roadbed. But we didn't trust it. At first we laid plywood underneath, Homasote on top, expecting that the paperboard would sag and the plywood would shore it up. To our suprise the situation was the other way around...In several places [on my railroad] the 1/2" plywood has sagged out from under the 1/2" Homasote. The plywood isn't doing the least bit of good... The answer is that one layer is enough. For most layouts 1/2" Homasote ribbon roadbed is sufficient and economical." SO....Without knowing why the statement you quote was included in the second edition, or if the whole quote above was taken out, I don't know that I can agree with your take on Linn's position. One thing I'm sure of is that if Linn were still with us, he would be able to expound on one-layer vs. two-layer at length. I will say that I built my layout literally by his book, and everything worked as well as he said it would. Personally, I can't figure out why plywood would be necessary, and I can think of a lot of tasks (e.g. installing under the track switch machines) that would have been more painful with plywood present. Yes it's harder to find, but it's worth it. (For everybody's info, Homasote and Upson are brandnames, the generic term is paperboard.) Incindentally, in Linn's book he distinguishes between open-grid, flat-top and cookie cutter techniques, all of which can be used over either L girder or butt joint framing. BTW Dave, that cookie cutter helix seems like a great method.
jagged, Thanks for your experiences with Homasote. If I knew where I could buy it, I'd use it. But, I'd put 3/8 or 1/2 plywood underneath it and glue the two together. I don't like the flexing issues I have with 3/8 and 1/2 ply alone and unreinforced Homosote would be even more flexible. Dave told us he had to use twice the braces with Homasote alone so the flex issue is certainly there. Dave, I have seen your use of OSB with Homasote and agree that bonding the two together would give super results, especially in the helix configuration. Thanks for providing your input on this interesting topic. Joe Daddy
Construction of a model railroad I'm probably a little late on getting in on this. The following is just my opinion and you are entitled to yours. I don't think there is a wrong approach when constructing a layout unless you are using jell-o or a custard creme pie as your base.<G> Yummmmm! Hollow core doors, wood benchwork with cork roadbed, plywood sheeting, presswood, cookie cutting techic and blue foam are all excellent bases for a layout. I constructed my railroad using the cookie cutter technic with a combination of presswood as the sub-roadbed followed by cork road-bed, pine risers (or whatever wood is cheapest) and box construction of 1X4's or 1X3's as my base. I might use L girder if I have a long run, approximatley 9 feet without any footings or legs that support the middle of the span. I choose not to use homasote because I am allergic to it. I can't even walk into a layout room where homasote has been used. Aaaarrrgghh! I've attached one picture. I've posted other pictures in the RailImages department. My advice would be to pick what's easiest for you and go for it. Nothing wrong with starting with a hollow core door. Plan on expanding it...because you will. <G> The layout pictured here started as a 4x6 over and under railroad. It has gone through 5 expansions...since it's conception. This time around it is getting a major overhaul. Have fun and enjoy!
Other I'm building a shelf layout and use slotted shelving brackets. I then plywood on the shelf arm and foam board on top of that.
4 inch wide strips of plywood with a 5/8ths top. Some areas have 1 inch foam added to that for terraforming below grade. Brian
Half around the walls shelving attached to wall studs with diagonal bracing and hardboard layout surface. The other half (yet to be built) I'm thinking about trying hollow core doors with attached legs, since these modules have to be movable. Problem: finding leg assembly method that is (a) stable, (b) relatively inexpensive, and (c) same height as shelving -- 57".
Another other here. Right now I'm building on an expanded door...kind of an outrigger configuration. The door is in the middle, with open grid expansions down both sides to make a 42x81.5" footprint. The whole thing is topped with 2" foam, and sits on an old dining room table. The open grid "bays" down either side carry the wiring and connections under the foam. In the past I've made train tables using open grid with plywood over, and foam filled torsion boxes with 1x perimiter and 1/4" luan top and bottom. Both worked well for the situations they were designed for. If I had the space for a bigger layout, I'd probably use a combination of things for different sections...shelf brackets, L-girder, doors, steel studs, etc...but most to all would probably be foam topped.
Now for my two and one half cents worth. I chose other, why you might ask. Well I'll tell ya. I have been building modules (1" x 4" Furr butt joint with pine T risers. Masionite 1" x 1/8" Spline sub roadbed with Califorina Roadbed (Homasote) for the track to be spiked too with foam scenery build up's) untell the hobby room is built. I like the flow I get with Spline as oposed to cookie cutter and I can build in easements automaticly, with T risers I can change elevation in a snap. With the Califorina Roadbed (Homasote) I prime it with a latex primer and sand it smooth to lay the ties down with white glue and sand them when dry. I then stain the ties and let them dry, then I start hand laying track (Plates, Rail code 138, and spikes). When I get into the hobby room next fall I will use a combination of my modules (Butt Joint), L girder (Gives a flowing and curveing front facia to it), Mushroom, and along the wall which ever deems it's self to be the right choich. I am not so sure about useing alot of foam for scenery especialy that large of an amount. It's one thing to have it in some of the modules, but the entire layout! I think not that would be a fire hazzard. Paper and cardboard attracts bugs (Silverfish). I might take a cue from Andy Dodge and use masionite strips, wire screen, and zip texture scenery. Heavy for sure but hay, I'm not going anywhere for twenty or thirty years. As Linn Westcott would say: " Every system has it's good and bad points". I think it is up to us to find or see what works best for each application we run into. And if we listen carefully enough they will speak to us. "Line a hundred men up and tell them to dig a ditch, You will get all kinds of ways to dig a ditch, but you will get a hundred ditches" General George S. Patton "Still Training After all These Years"
