The flat car with decking will be comprised of a brass frame, for strength and weight, with a styrene outer framing and decking.
Remember the following rules:
In O scale; 0.020” scale = 1” prototype. After a while this will come naturally to you.
To completely cure (dry) either plastic glue and ACC requires 24 hours.
Plastic glue interferes with ACC and vice verse.
If you forget the rules you will have trouble!
Styrene flexes; therefore the main part of the frame has to be made from brass. Since the prototype locomotive is no longer in existence all dimensions have to be taken from drawings, photos, and the modeler’s experience.
My son is an expert carpenter and woodworker, he answered my questions regarding the dimensions of lumber used by examining photos. This took the guess work out of building the model.
To start off, immediately the fact the trucks have a 78” and not a 72” wheel base has to be taken care of. The trail truck was screwed onto the body bolster provided with the trucks. It was then placed on a sheet of paper. An arc was drawn from the outside corner of the truck frame on the paper. The arc was compared to the side and bottom scale drawings of the deck. It looks like an additional scale 9” has to be added to the end of the frame at each end for the trucks to clear the foot boards.
This is not a lot when one considers the side frames themselves are wider than the prototype. In O scale the prototype gauge is 5’ and not the standard 4’ 8-1/2”. This additional width causes problems in almost every O scale model.
The central framing will be of brass. I make non-scale drawings for almost every part of a model to be scratch built. It helps me to understand what has to be done plus the size of the material to be used.
The drawings are my “imagineering” of the model. Sometimes drawings are made and then not followed for one reason or another. Only the drawings or parts of drawings which were followed are included. No two drawings are to the same scale.
Also, since these drawings are for my use, they are not always the best. However, I do try to make the lines straight and the drawings clear enough.
The “I” beans are 3/16” x 3/32” x 7-5/16” with the end piece being solid brass 3/16” square x 1-3/4” long. To help with the spacing of the “I” beams this jig was made of styrene. Since the jig is made of styrene it cannot be on the brass during the soldering process. Once the “I” beams are in place using the jig, place a heavy weight on them. Square everything up before soldering.
A very effecting soldering flux is 0.1 M zinc chloride dissolved in 0.1 M hydrochloric acid. This is the material in almost all soldering fluxes. If you become friends with the local high school, community college, or college chemistry teacher; you might be able to get this solution made. One liter of the solution will last you a life time. Be cautious! The solution is caustic!
The pieces of the brass frame were soldered together using 6% silver solder. A propane torch was required to provide enough heat. The joints are butt joints; therefore, a fillet of solder is required on each side of the “I” beam for strength. Be careful not to file away too much solder. If done correctly there will be no excess solder.
Don't put the propane torch away just yet. There's more soldering in the next post.