Drop Leaf Recommendations

Model Railroader General Discussion (Model Railroader)
1

I’ve decided to add a piano hinged drop leaf to our 4x8 layout, which will add 18 inches to the long dimenson, as shown below:

The current plan is to cut a 24" x 48" piece of oak veneered 3/4" plywood and attach it to the layout at roadbed heigth with a 48" piano hinge, and add a 48" stiffener made of oak 1x4 under the leaf so that diagonal braces up from the main table legs will butt against the stiffener when the drop leaf extension is level.

Each of the 4 longer and two short spurs will be wired through a deadman switch and then through a DPDT panel switch so that each is isolated in it’s own electrical block. This will prevent sail-offs when the leaf is in the down position, and allow us to stage three long consists and two short consists, driving them onto the main layout and back off again at our discretion.

All of the new track will be covered by a removable mountain module, so it won’t need to be ballasted or have to look pretty, but it does need to work reliably.

I have at least four questions.

  1. Do I need a short piece of track to drop into the splice, after the leaf is broiught up, or can I simply butt the rails together after the leaf is fixed in place with the hinge and expect reliable tracking? In a perfect world, raising or lowering the leaf would be as simple as possible, the extra steps of threading four short sections of track and joiners on each time the leaf is raised or lowered would be a negative benefit. On the other hand, I won’t settle for less than reliable operation, so if the short sections have to be used, then we’ll use them.

  2. Do I want the structural joint between the existing layout and the new drop leaf to break perpendicular to the track at that point, as indicated by the dark blue line in the planview above? Or will a rectangular drop leaf where the tracks cross the structural joint at an angle work reliably

2

There must be a good reason for the drop leaf, instead of a permanent extension ie; section when in use blocking door or traffic area.
I feel that if you securely mount and position the drop leaf, you could lay the roadbed and track then make the clean cuts w/ a dremel cutoff wheel. Having the joint at as close to 90 degrees would allow less chance for derailments. The support bracing can be set up so that there is some sort of adjustment to always bring it up to level.
Bob K.

3

First off, I’ve never built one of these myself, but I’m thinking about something quite similar. Rather than a mountain, I would use a vertical scenic divider, which could be made removeable. Then, I would lightly scenic the dropleaf as a yard. With the space open and visible, it gives you the advantage of a “fiddle yard” where your 0-5-0 switcher can make up and break down trains. Otherwise, you have to build your trains out on the main line and move them into the staging area beforehand.

I like the idea of having the tracks meet at a right angle, and also the idea of dowels for alignment. Once the drop-leaf is installed and you are satisfied that the hinging is solid and that it closes repeatedly to the same position, then I would lay the track as if the drop-leaf were just another section of the layout. After the track is fastened down, thoroughly tested and ballasted, then take a fine saw blade or a Dremel and cut through the rails, ballast and roadbed at the break point. If this is done right, you won’t even need to deal with rail joiners when you open and close the hinge. Of course, you will need to wire the drop-leaf section independently, but you were going to do that anyway to get the open-leaf protection you’ve already described.

4

Robert,

Yes, there’s a computer desk off the right end of the layout and when the chair is fully out from the desk so someone can sit down, it’s within a few inches of the layout.

However, that’s my son’s computer, I never use it, and we need more staging. When the kids are at their mom’s, the leaf will be up. When the kids visit, if my son wants to run trains, everything is ready. If he wants to work on the computer, he will be able to drive four trains off the drop leaf, fouling the mainline, drop the leaf, and access the computer. It won’t matter if the main is fouled, since nobody will be running trains anyway.

In the long run, the whole layout moves to a new building out back, the drop leaf goes away, and two additional 4x8’ modules are added, one on each end of the existing layout. A temporary drop leaf will buy us staging space now, and not be too hard to swap out later on when it’s time to build phases two and three.

I know the trackplan looks a little like a spaghetti bowl, but when you factor in the scenery, it looks a lot different.

With the mountains in place, most of the track disappears, leaving a crowded interchange and yard, which Silverton was, a steep grade, which it was, and a rather isolated Red Mountain mining area, which it was. I’m real happy with the way the track’s working so far. Although early adjustments were necessary, we almost never have to pull a mountain to access a derailment, even the hidden turnouts are woring very well. Operations function as expected, though it’s a bit of a grunt getting freight up the hill, which it was back then too, all we need is a little more staging and to fini***he plaster and terrain paint, and then we’re ready to start building structures and detailing.

Thanks for your opinion on how to make the drop leaf joint. I suspect it wil take some fiddling and adjustment to get the new

5

Mr. Beasley,

That’s two votes for not using short joiner sections, good news!

The foam for the mountains is already in place, glued together such that the lowest two levels of 2’ foam are fixed to the benchwork, and the upper mountain modules are glued together but not down to the lower sections.

All the plaster cloth for the lower two foam layers is in place, and the tunnel interiors are either sculpted and painted, or else are easily accessible with the mountain tops removed. I have to say that clearance inside some of the closely spaced tunnels was very tight, adding dividers was risky, but we figured out that by drilling holes in the benchwork and gluing vertical dowels in them, then adding duct and masking tape as a framework to hold plaster cloth until it set up, we were able to make very thin dividers that are still structurally stable and I think we’ve got those issues licked.

I like your idea of leaving the drop leaf staging area visible, but it isn’t as simple as that. The ridgeline at the far right of the existing layout is 21 inches above the level where the new staging tracks will go. It would be difficult to get the terrain down that low that fast, so the plan was to have an 18" by 48" by however tall removable shell to cover it with.

Now I think I’ll fini***he existing ridgeline as a vertical rock cliff, go ahead and build the removable shell too, and then we can have our cake and eat it too.

Most of the time, staging represents trains coming up to the interchange from Durango. Since Silverton is the end of the D&RG’s line, they drop the cars there, and the Silverton road is responsible for making up the new, (and very much shorter) trains for hauling the freight up to the mining district and hauling the ore back down to Silverton. So most of the prototype operations rerquire that trains be made up out from under the staging area anyway.

But now, thanks to your idea, we can pull the mountain module over the d

6

To assure that the two ‘bridge abutments’ (benchwork on the two sides of the leaf) remain aligned, there should be a mechanical connection between them. A sheet of plywood (with beveled edges to prevent catching shoe toes) with the benchwork legs anchored to it should do the trick.

I’m looking into building a “bascule” design, with the hinge located about 8 inches away from the end. This will mean that the surface, with trackwork, catenary and some detailing, will be protected from accidental bumps. Only the bottom (plywood and a couple of steel studs) will be exposed to contact. The short end will drop , while the longer end will rise above layout level when in the open position. At the moment, this (and my entire layout) is in the early design stage, so construction and testing are still a couple of months in the future.

Chuck

7

Chuck, I’ve thought about protecting the drop leaf, but this is a low traffic area, and it’s really only suitable for a standard hinged drop leaf. If there’s any tendency to snag passers-by, I can add a lip to the edge of the leaf which will keep people further away.

Any thoughts on how you plan to accomplish your electrical connections?

8

Jeffers_mz

The leaf will only carry two through tracks, no turnouts and the catenary is purely cosmetic, so only four connections are needed for power. The elegant way would involve plugs and sockets that would automatically disconnect both leaf and approach track power unless the leaf is fully down and locked. Installed at both ends, they would also provide positive mechanical alignment.

Of course, I mean something like house AC plugs and sockets, not miniature electronic parts.

Chuck.

9

Jeffers, I have a couple of thoughts on your situation:

For rail power connections, you could try making pressure contacts similar to the ones I made for my swing gate. Check out http://www.kcnet.com/~gmcrail/swing_gate/swing_gate.html

To prevent drive-offs, you could use the proximity reed switches sold for alarm systems to trip a relay. Wire the relay to power the approach blocks only when the leaf is up.

I would definitely engineer a means to fine-adjust the gate’s final position. Humidity and temperature variations can wreak havoc on a nicely-aligned initial design.

10

Just so you know. If you use a piano hinge and it is aligned correctly, as in the tops are level both sides[ if not, then sand them], then alignment pins are not needed at all. The piano hinge will do that job for you.
Second, when putting in the piano hinge make sure that you put a screw into AT LEAST every second hole. Any less will skew the integrity of the hinge and it will lose its purpose.
Third, I think that the link above for contacts works well and you should use it.
Fourth, you can also use the contact idea to make a deadman switch. Simple connect them only when the opening is closed. Wire the lead tracks to that contact. Now that area won’t work unless the leaf is up.
If you double up on the ties at the break you won’t need a splice. Looks wierd but it works on curves.

I hope that helps.

11

Jeffers

Stephen has a point. The piano hinge is going to produce a rotary motion, as the section swings into place. Alignment dowels, even when tapered, produce close clearance alignment for a linear motion. In your case, the dowel alignment cannot be close tolerance in the vertical dimension - but it would help maintain alignment in the horizontal if the dowel holes are enlarged in the vertical only.

To help maintain the integrity of the piano hinge alignment over time, I recommend a removable/movable support that takes the weight off the hinge in BOTH the raised and lowered position.

As far as the track ends go, portable sectional and modular layouts where the rail ends run to the edge (no fitter sections) often solder the rail ends to PCB board or screw heads to avoid “zippering” the rail when it gets snagged in transport. You might consider how much snag potential - loose clothing, etc - your rail ends have, and plan accordingly.

my thoughts, your choices
Fred W