Peter's Model Railroading | The Equipment | Cabin Cars | PRR N6b
Construction: Body

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.

Again, for completeness, here are the two end walls cut to the final width.

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.