Home Page › Forums › Modeling the Missouri Pacific, Texas & Pacific, etc › Mopac or Texas & Pacific layouts › I’ve bit the bullet, Jan. 15, 2011 › Reply To: I’ve bit the bullet, Jan. 15, 2011
The turnback loops referred to in the last post are now well underway. A turnback is nothing more than a 180 degree turn, with the appropriate 6″ tangent at each end. These go at either end of the three-module set that covers the north Wichita industrial area, so they’re both double track, and they should be module numbers 19 and 23. One was definitely going to be 180 degrees, and the other seemed to need to be a little less but I determined that the 180 degree angle would work, which vastly simplified the construction.
Building the turnback in two halves, with the joint at the halfway point consisting of the same end plate that any module would have, allows for future changes. These intermediate end plates are actually bolted together with enough give to allow a little elevation change if needed. Earlier turnbacks had a 12″ width at this joint, but these have a 15″ width (aided by the fact that I cut some end plates wrong so had some salvage material to work with). This should look better with city scenery, of which there is none now.
The inside side plates are the standard 1/2″ birch, mitered into roughly 40 degree and 50 degree angles. This connects the end plates rigidly with the intermediate end plates, and allows for the outer plate construction which has short 3/8″ segments at the end, with 1/8″ laminated over it and bent in a continuous curve. This was a bit of a challenge since the circumference of each quadrant is about 67″, requiring splices. The cross section of the outer edge of the module includes a horizontal plywood reinforcement, cut to 42″ approximate radius, which gives the finished fabrication enough stiffness. Intermediate braces are 1×3 like any other module, with 5/8″ holes bored in them for the wiring.
The next stage of construction will be to add the tops, followed by subroadbed.
