Paul’s been back in touch.
Not long he sent in pics of his Chickadee Hollow railroad. You can see it here if you want to get up to speed.
This time, Paul walks us through his clever removable bridge:
This concept shown can be adapted to any type of bridge that you want to be removable, yet adjustable, while providing access to your layout.
The first photo is the bridge shown on my layout that is the subject.
The second photo shows the mechanical items that make it work.
I used 1/4 -20 flat head bolts that I cut a slot in the end for a screwdriver.
Also shown is a 1/4-20 T-nut and one of the bolts shows a 10 mm super magnet which was superglued onto the head. This is typical to all the bolts in the system.
The 2nd photo is #2779. Various photos show the slot cut in the end of the bolts. Before gluing the magnets onto the bolts file the top of the heads so that they are very flat.
Various photos showing the underside of the bridge and the relationship of the mechanical & electrical components.
The photos below show the electrical contacts with a 10mm super magnet glued to the flexible copper strip which automatically adjusts to provide a good electrical connection.
This also shows the wires which go to the tracks and to the power source. Obviously you need one for positive and one for negative.
The stationary contact is a steel angle with the copper wrapped around it. This provides the stable contact and also the steel to which the magnet is attracted.
These photos show the underside of the bridge with a thin washer glued to the wood to provide something for the magnet to grab. You can use any steel or iron that you have but it must be flat. This has to be located wherever a magnet must attach.
Also note the structure of the vertical lift mechanism. I chose to use 2 screws so that I could a adjust tilt if necessary. The lateral adjusting screws are attached to the movable structure, in this case the bridge itself. Use T nuts for the internal threads where needed. I also glued the T nuts in place.
These photos show the stationary contact which is a steel angle with the copper contact bent around and glued to it.
Also shown is the Atlas rerailer track used to assure that the train wheels align properly. These rerailers are used at both the entry and exit from the bridge and also on the stable layout entry and exit points.
If you decide to use this method on your layout you should design it so that the adjustment points, both laterally and vertically allow both positive and negative adjustments. What I mean by this is that the adjustment screw placement should allow the track to go beyond the ideal position both vertically and horizontally.
Also I used the magnets instead of just bare screws to provide control of the positions by keeping everything pulled together.
A big thanks to Paul for taking the time to send this in. Clever stuff.
Now on to Gary who has come up with an interesting effect:
“Tunnels made from roofing foam and pillow stuffing.
That’s all for today folks.
Please do keep ’em coming.
And if you want to make your start, on your very own layout, the Beginner’s Guide is here.