Introductory Note:
As I am designing the car in a CAD program, when I have the design of a buildable portion of the model done, I am going to start building it, because I am excited about getting this project underway. In the past, when I have scratchbuilt a car, I built several of them at the same time. This time around, I am going to focus on just building one car. One, I don't need that many cabin cars, and, two, my hobby time is extremely limited; I really don't want this project to go on for years. But, as I am designing the car, I am also thinking about how I am going to build it, and specifically, in which order I should build the parts. So, some of the following paragraphs will start off with "(to-do)" to indicate that that is a planned activity. As I actually start building the model, those sections will be replaced with how I did indeed build the model and show accompanying photos. This approach allows me to pre-document how I am going to build the model and keep track of any thoughts I might have before I get to that build step. You can think of this as my own "kit instruction sheet" that accompanies a kit that only provides a bunch of raw materials.
I am using Kappler Mill & Lumber's Scribed Siding (part #KP004P12). There are two sheets in the package, each measuring 12" long and 3-3/8" wide. The package states a width of 3-1/2", but that's not what you get in the package. In S-scale the scribed boards come out to 3 scale inches, which is close enough to the 3-1/4" that the prototype used.
(external link: Kappler Scribed Sheets)
This is the official start of the construction phase of this car. I am building the exterior walls of the main body first. That sets the exterior limits of the model, against which everything can be built. The first step is to cut the two long side walls. Since the exterior walls have the boards running in the vertical orientation, and since the Kappler sheet has the boards running in the full 12-inch length, I have to cut two pieces for each side wall and carefully deal with the splice to make it as inconspicuous as possible. So, each 3-3/8" of the Kappler sheets covers 216" scale inches. The overall width of the car's body is 295.75", so the second piece has to be at least 79.75" scale inches wide, or 1-1/4". The exterior walls are a scale 7' tall (or 1-5/16" in actual measurements). To accomplish this I set my mini table saw to cut three strips of a scale 7'. One of these will be used to make up the full lengths for the other two.
I set my calipers to the required full length of the side walls, i.e. a scale 24'7-3/4", so that I can prepare to mark off the full length to which to cut the side walls. I have found these mechanical calipers to be invaluable for making accurate measurements. I used own a digital pair and they were horrible as far as accuracy. And, of course, the white part of the calipers mark off the S-scale inches, so it it near trivial to count exactly down-to-the-inch measurements with a tool like this. I then use the inside-measurement arms of the calipers to actually set the distance between a stop-block on the mini table saw and the blade doing the cutting. This gives with a 100% accurate cut.
Of the three side walls pieces I had cut, I cut one down the center, and then glued its parts to each of the other side walls. The way I did this was to first sand the parts, then spread a very thin coat of glue to the edge end of one of the boards, pressed the short cut-off to it, and then put a strip of blue masking tape over the two parts. The tape acts as a clamp. I put metal weights over the two parts to make sure it stayed flat. I did all of this on a glass plate, again, to make sure that the entire side wall assembly stayed flat. Of course, the two parts have to line up at the top and bottom edges. I repeated this for the other side wall and let it dry for several hours. This glue joint is quite weak, so I have to handle these side walls very carefully. When removing the blue tape, the key was to pull back on the tape at an acute angle, so as to not break the glue joint. The next day I took this photo in preparation for making the cut to trim the side walls to their final length.
For completeness, here are the two side walls cut to their final length. If you look closely, you can see where the two shorter sections are in these assemblies, but there is no visible glue line or even a wider gap at the joint than what is there between the board slats. So, I am happy with how this edge-gluing process came out. Once painted, it should all but disappear.
The exterior end walls are next. These are, at their center, 7'8" tall. I designed mine to fit in between the side walls, that way the gap, such as it is, between the end walls and the side walls, is harder to see. So, to size the width of the end walls correctly, I had to do a bit of math. The prototype's body width is 9'1-3/4". This scales out to 1-47.75/64" in S-scale. I then took the two side walls that I had already cut and firmly pressed them together and measured their combined thickness with the calipers. They came out to 8.75/64". So, subtracting that from the desired full body width yielded that the end walls need to be sized to 1-37/64" wide. The calipers are set for that dimension, and luckily it just a bit less than half the width of one of these vertically-oriented strips I cut off from the Kappler sheet.
The CAD drawing I had made, wound up with a end-wall top radius of 378", or 5.9 actual inches in the S-scale model. I decided to use a compass (the drawing-tool kind) to set up that radius. I then marked a pair of perpendicular lines on a spare wood board. I also drew a line in the center of the backsides of the two end walls. This then allowed me to line them up with the crosshair on the board, and I could then place the compass such that it could draw the portion of the top arc on to the end wall. I repeated the step for the other wall.
I clamped the two end walls together, and using my Ultimation Sander, I sanded most of the top of the end walls off to close to the line. I then used a file to fine-tune the sanding. By keeping the two walls clamped together, I could make sure that they matched each other.
By lining the side and end walls up against a ruler, I verified that they all have a matching height.
-------------------------------------------------
Note: I have decided that I just cannot devote the required time, devotion, and energy that this project requires at this point in my life, so I have postponed working on it for a good while
-------------------------------------------------
(to-do) Before gluing the four outside walls together, I am going to cut out the openings for the windows and the doors.
(to-do) Next, I'll glue the four exterior walls together. This will be a delicate, butt-joint construction, so it has to be handled carefully.
(to-do) Measure and cut the interior walls to fit the actual exterior-wall assembly. The prototype uses at least 4x4 framing members and then applies an interior wall to those. For the sake of available interior space, I am going to just glue the interior walls directly to the inside of the exterior walls. The prototype uses the same size of board, but the boards are oriented horizontally. Since the Kappler boards are scribed along their full lengths, I will be able to cut the walls from the sheets to fit their full length. This will then also strengthen the side walls' splicing that I had to do. These interior walls need to be shorter than the exterior walls, because the car's floor is to be mounted against them from the bottom.
(to-do) After cutting and fitting the interior walls to the exterior-wall assembly, I'll use the window and door openings of the exterior walls to mark where the interior walls need to have their matching openings.
(to-do) After cutting the openings, it is then just a matter of gluing them to the exterior walls. These interior walls, which are shorter, vertically, than the exterior walls, need to be lined-up at the tops. The assembly should now be a lot stronger.
(to-do) Knowing the actual interior dimensions, I can now cut a sheet of styrene to act as the floor, and then use 5-minute epoxy to glue it against the lip formed by the interior walls. The assembly should now be square and solid.
(to-do) There are several decisions that I need to make at this point. One, I want there to be enough material inside the car for the truck-mounting screws to "bite" into to keep them solid (the scale bolsters aren't sufficient for that). Two, I will be installing the S-CAB BPS-Lite board and battery into this car, so that I can run the interior and exterior SMD LEDs that I'll be using. Third, I need to decide to what extent I am going to detail the interior. The Kaslo Shops PRR N5c kit that I built came with a full interior. I used the same lighting system, but when it is all said and done, not too much of the interior is actually visible, so there is a point of diminishing return on this.