need pictures of how to do a drop leaf in a HO layout

Drop leaves are not that nice to do as the top ends up being pointed out and this allows the scenery and buildings to be swiped against when the dorp is down. If you go far enough and put it in storage 180 deg. from the extended direction, you may also still have problems with hitting the scenery, etc. when putting things under the layout. Building one is basically easy provided you don't have to join to something on the swinging side - just put the hinges on the bottom side of the benchwork and provide a few alignment arrows, pins or such to align the track between the sections. The alignment pins also need to go near the top of the framing and hopefully near the track so the track can be properly aligned by the alignment arrangement. A simple leg or two into a stop will provide support when the section is up.

-- Why isn't there an Ozone Hole at the NORTH Pole?

Drop leaf layout sections are never a good idea. Good alignment, even with locating pins, generally lasts just so long. Except for simple ground cover, anything on top of the board is very likely going to be caught or knocked off sooner or later...including the track ends. Likewise, if the track enters the board at anything other than almost a right angle, alignment will certainly fail in short order (remember the fit is hardly a machine fit and liable to all sorts of flexture). Since the drop leaf is unlikely to be as rigid as the main layout, flexture will also result in ballast, dirt, poured roadways, etc, cracking and falling off.

CJ831

OK, E.T., now that you've made your plans clearer it's obvious we're talking about a bridge section for the layout. I took your original post to indicate a fold down addition or spur to the layout. A bridge section won't have nearly the problems I originally mentioned as the track does approach at 90-degrees to the edges, it will be short, and would be unlikely to have much scenery on it anyway. I seem to recall that Tony Koester had a detailed article in MR recently on a very well thought out design for just such an item. You might be able to find reference to it in MR's magazine index. Incidentally, a lift-UP section would be better than a drop-DOWN design as a far more rigid support could be accomplished when the bridge section is lowered into place. A drop-down design would have to rely pretty much just locator pins for support and alignment.

CNJ831