The benchwork is coming along nicely.\u00a0 There is almost 60 feet of L-girder framework erected now.\u00a0 Hopefully I’ll get another 23 foot section done this weekend.<\/p>\n
One of the construction tasks is going to be the fabrication of a bridge section to span the doorway into the room.\u00a0 I’ve been thinking about this for quite some time and had briefly thought about several different options: a swing-up section, a lift-out section, a lift-up section, a swing-down arrangement, and a swing gate.<\/p>\n
I dismissed the swing-up section (a bridge hinged on one end) because the 4 foot length of the bridge is too tall and would hit the ceiling.\u00a0 Then I dismissed the lift-out because of the inconvenience of lifting out, then storing the section.\u00a0 The lift-up section (the entire bridge rising vertically) seemed outlandish.\u00a0 I really didn’t think much at all about the swing-down approach (another bridge with a hinge on one end); it just didn’t seem sexy.\u00a0\u00a0 I finally settled on the swing gate.<\/p>\n
Now I started planning what the bridge would actually become.\u00a0 I decided early on that I wanted a low lying tract of land coming out of Monterey that would feature the track crossing over a marshy area on a long, low timber trestle.\u00a0 The only place such a trestle seemed to fit in the trackplan was (you guessed it) right at the point where the track goes past the doorway into the room.\u00a0 I finally decided that to model the trestle in this location I would have to build essentially a box with a depressed area in its top.\u00a0 The box would be about 4 feet long, 12 inches wide and likely about 8 inches deep.\u00a0 I figured the bridge would normally be open, but wanted the bridge to be capable of functioning as a duck under during a session.\u00a0 As the design developed (and after studying every swing gate I could find on the internet), I concluded that trying to support such a bridge with a hinge or two on the side of one end would likely not work very well in the long term; there would likely be too much twisting and wracking in such a design.\u00a0 So then I added structure to the bottom of the box to essentially make something more like a Dutch door.\u00a0 Of course then I lost the possibility of a duck under.<\/p>\n
But there was another problem bugging me.\u00a0 There are five wall switches for lights and receptacles located right next to the door opening.\u00a0 Going straight across the doorway with the bridge section would have had benchwork blocking several of the switches.\u00a0 Hence, the bridged section is at an angle as it crosses the doorway (see trackplan on the website), allowing access to the switches.\u00a0 With this configuration, there is an angled section of benchwork poking out to start the bridged area.\u00a0 Because of this, and my desire to keep curved track off the swing section, I found that the required hinge point would not allow the bridge to pivot and come to rest flat against the layout when open.\u00a0 It would instead be sticking out into the aisle, partially obstructing it.\u00a0 I was becoming unhappy with the swing gate concept.<\/p>\n
Next up was another review of the vertical lift bridge (the lift-up section).\u00a0 I had seen something along that line on Charlie Comstock’s Bear Creek and South Jackson.\u00a0 He uses that idea to provide an access pop-up on his layout.\u00a0 It uses a pair of drawer glides oriented vertically and seemed simple enough to build.\u00a0 I figured I could build a beefier version of this as a bridge.\u00a0 Then a few weeks ago while erecting the first benchwork sections, a thought occurred (sound of hand slapping forehead).\u00a0 There is insufficient clearance over this section of layout for a raised bridge due to the lighting valence passing overhead.\u00a0 Bam!\u00a0 Idea dead!<\/p>\n
So that leads me to my latest thoughts: the swing-down section.\u00a0 Wayne Robichaux had suggested this so I did a couple quick sketches, and it seems like the idea may be better than I first thought.\u00a0 By using a rod within some bearings (something akin to an axle), and placing it an inch or so down and inboard of the bridge-box, the thing would swing down nicely and would tuck up under the layout when down.\u00a0 My next thoughts are ways to latch it in the up position, and whether it will need assist in the lifting operation.\u00a0 For the latter, I’ll have to figure out how much the thing will weigh, which will probably require me to at least gather some materials of the approximate size required to build the bridge-box.\u00a0 Once I know the weight, I can more reasonably come up with a design for these other tasks.<\/p>\n
So that is where I’m at.\u00a0 I would like to figure all this out early on, as this bridge is essential to even the earliest operation of the layout . . . Monterey is inaccessible without this bridge.<\/p>\n
Got any other ideas?\u00a0 Comments are welcome.<\/p>\n
-Jack<\/em><\/p>\n","protected":false},"excerpt":{"rendered":" The benchwork is coming along nicely.\u00a0 There is almost 60 feet of L-girder framework erected now.\u00a0 Hopefully I’ll get another 23 foot section done this weekend. One of the construction tasks is going to be the fabrication of a bridge … Continue reading