I'm building my first HO layout since the 1980s using the L-Girder method. The layout is a simple 7' x 9' L shape with a 24" deep roadbed. Those who are alert will realize I'm using standard length lumber (1"x2" & 1"x4") and 1/2" plywood "handypanels" to minimize cutting. I've read numerour articles and seen numerous videos and now am confused.
Some of the resources show risers or joists mounted to the tops of the l-girders. Others show just "ribs" between the l-girders. From what I've gleaned, with just 2' of plywood for the roadbed with 4'x4' panels for the return loops, the l-girders can be set set back 3" from the panel edges. Confused yet?
Right. So now my question. If I affix the panels to the l-girders in this layout, is it necessary to have joists or risers? The 4'x4' panels will probably need some additional bracing I'm guessing. Thank you.
If you were going to just attach the top to the L girders with no risers, then you might as well save wood and not use L girders, just make a box frame. For a plain flat bench, L girder is IMO overkill. The more common use of L girder support structure is to then add joists with risers to support narrow strips of subroadbed, rather than paving over the entire layout with sheet material.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
You would use joists (stringers) and risers generally in areas with cookie-cut subroadbed, thus minimizing the use of full top surface boards (and wasting a lot of wood, imho, by cookie-cutting the sub-roadbed).
For example:
Alternative method is spline subroadbed, which requires quite a lot of effort of cutting and laminating individual strips of wood, but offers beautiful and natural looking curves.
Also, you could put the entire top surface board on the risers, helping you level it. Technically, you could build the benchwork itself over a rough and uneven floor, and then have a perfect level of your top surface.
Stringers on the L-girder benchwork are beneficial when you need to move them, let's say a turnout happens to be right beneath a stringer. This is not possible with traditional open-frame (box) benchwork (without much effort, or at all if it's already affixed to he wall and one side is totally inaccessible). This is why the L-girder benchwork is popular, the L's allow you to screw stringers to them from underneath, and move them as you please.
The drawback of L-girders is the amount of vertical space needed to accomodate the entire structure, and generally would be used in single deck layouts, although there are always exceptions to the rule.
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What Randy said.
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
rrinker If you were going to just attach the top to the L girders with no risers, then you might as well save wood and not use L girders, just make a box frame.
Bingo ... second vote for Randy’s suggestion. after I thought a lot about the L-girder, I realize that it’s only useful for the cookie-cutter method for large layouts which of course is a lot of cutting. It also makes it a heavier structure which you don’t need given 1/2” plywood is incredibly strong at keeping things together. (see more below) Somehow people extol the L-girder method.
For my around the walls layout in a 23x16 basement, I did not use L girder even though I have a lot of risers (my layout gains elevation the whole way around to go the second level. a box frame made with 1x4 lumber, with 24” on center beams, covered with 1/2” ply was strong and so light, that I cantelever most my layout off the cinderblock wall. No legs = better access, more flexibility for putting storage under and easier cleaning. It will work for your 7x9.
NP.
isn't the other advantage of L-girders is that you can relocate the joist if it blocks access to the layout above it, for example putting a switch machine under a turnout?
greg - Philadelphia & Reading / Reading
Sure, but across 2 layouts with box frames, with about 3 dozen turnouts across the two, I had ONE that was a bit close. Of course, with a 2" foam top, the box frames were built on 2 foot centers, not 16" so there were fewer crossmembers to get in the way.
Another advantage to using servos instead of giant Tortoises, they fit in more spaces. Even with L-girder, if it's a RISER that's in the way, are you really going to reengineer all that to move the riser a couple of inches (risk messing up a nice smooth grade) or just move the location of the offending turnout an inch or two further along the main so the switch motor fits?
Note I WILL be using L-girder on my basement size layout, because most of it will be open construction, plus I want to minimize the number of legs to maximize the storage space underneath. On several walls, the rear L-girder will be screwed right to the wall studs, the frint one along the rear wall can be supported just on its ends and not exceed the recommended span distance as there will be a penninsula wall in the middle of the room, to one end wall to the penninsula wall will require no legs.
One other thing often touted for L-girder is that is allows less precise carpentry. I'm not sure I get that one, either - at SOME point you need accurately measured pieces of wood unless you don't care about up and down grades and poor transistions - in which case you must also not care about trains running reliably. OK, so the girders and legs don't have to be truly level because the risers compensate for that - well, the risers have to be accurate to get level tracks or smooth consistent grades. Or the joists don't have to be, in fact it's better if they aren't - a consistent length, and you can always go back later and cut off excess. But I also postulate that if you are not able to accurately measure with a tape measure and cut along a marked line, you will have a hard time screwing up from the bottom of the L-girder and catching the 3/4" wide piece of lumber used for the joists. I guess I've always been decent at caprentry, marking cut lines with a square, remembering which side of the line is the keep side (by marking the scrap side each time) so I can place the saw blade properly to get the length I need, not the length minus the width of the blade. Mostly all learned watching my Dad and Grandfather when i was a kid. The layouts I built as a kid all worked out fine with box frames and plywood tops, all using hand tools. I even built half of my last layout using hand tools to cut the wood because I was afraid a power miter saw would be too loud since I was in an apartment. But I had the second and third floors of the place and the layout was on the third floor, so eventually I said the heck with it and went with the power saw. Could barely hear it right below in my kitchen, doubt the guy in the first floor apartment could hear it at all.
To me, having built both cookie-cutter and spline sub-roadbed, both with risers, and on both box frames with plywood decking and open frame with joists, and L-girders with joists, the L-girder's two principal and selling features are:
a. strength over long spans using vertical 1X4 and the top-piece of 1X2; and
b. ease of positioning joists in order to get the best geometry and placement of risers.
In turn, the risers allow varying grades and curves, and this means either foam or wire-and-goop/cardboard strip and plaster cloth/something-else terraforming to make hills, gullies, ravines, rock cuts, etc. between the courses of sub-roadbed.
If you don't want but a few lumps of mountains around which the tracks will go, and not grades, then go with open frame and extruded foam or plywood surface and lay the roadbed and track elements atop those. Keep it simple.
I build benchwork to suit the needs of the footprint of the layout area and what will be over it.
Where the front edge of the layout is in a straight line, I use a box grid. Screwing a single board (not a L-girder), to the wall studs, and then glue small blocks of same-size lumber to it at the grid intervals (14" to 16" is common) and, once dry, adding one screw as a mechanical lock; this provides a place to attach the cross piece. Then I add the front single board with legs, etc. as needed, and fill in the cross pieces to complete the grid. If the layout calls for a flat profile, screw the plywood subroadbed directly onto the grid. If the plan calls for grades and/or for the scenery to drop below track level, then elevate the subroadbed over the grid on risers. This is where the cookie-cutter approach becomes attractive.
Where the front of the layout footprint is curved, such as on a turn-back loop, I use a "modified L-girder" approach. I still attach the rear single board to the wall as described above (at the same level as used for the box grid sections) and then use an L-girder for the front board, positioned so that the cross members will be level (i.e. the top of the L-girder is level with the bottom of the rear board). This method adds some lateral support to the cross member.
The advantage of adding the L-girder concept is that you can "free-form" the layout edge at the loop section by allowing the cross pieces to "over-hang" the L-girter, as needed, for a smooth facia outline. You don't need to be exact in cutting the cross members during construction, because you can always shorten them, or attach extensions, later as needed.
I love techniques that hide my mistakes!
Jim
I've never built L-girder but it looks more complicated than I need. I've used ordinary open grid and it works very well.
Rio Grande. The Action Road - Focus 1977-1983