Tap Creek

The Chicago & North Western Tap Creek Branch


By definition, when you free-lance a structure you do not rely on a scale drawing of the structure in question. On the other hand, you might have a photo or two that you want to use as basis for you modeling, in order to establish the basic dimensions and look of the structure you intend to build. When doing such a drawing you can use the Relative Ratio method. That method is not something I have invented, but a commonly used routine. For those of you who are not familiar with it, it goes something like this:

· Obtain a photo of a structure similar to the one you want to model. Ideally you would want one front and one side view, but a single view taken at and angle and showing both the front and a side is sufficient.

· You also need to note the size of at least one model item that you will include. This can for instance be the size of an N scale window you already have. You can also get by if you happens to know the prototype size of any item on the photo. You can then obtain the model size of that item by use of you model scale , e.g. 1:160 for N scale.

· On the photo, measure the height of the item you have selected  The relation between that measure and the size of your model item is your relative ratio. As an example, let us assume that a window on the photo measures 1" and the corresponding model window is 1/4". Your relative ratio would then be 1:4. In real life your ratios would not be that easily calculated. You would like to use a calculator to do the division.

· Now you can measure other dimensions on the photo, such as the height of the complete building and the height between floors. Assume we measure the height of the building to be 5" on the photo. By multiplying this number with our ratio (1:4) we get 5/4", which is then the height of the model house.

· If you have a photo that is taken at an angle, you cannot directly use the above ratio to decide horizontal dimensions. The sharper the angle, the less accurate the calculation will be. Instead try to identify a horizontal item on the photo, such as the width of a window, and calculate another ratio for that in relation to the width of a model window.

· At the end, do a simple drawing using your obtained data. If you find anything to be out of proportion, just change the measures until you are satisfied. That is the beauty of free-lancing

Return to the Brick House project description page.

The Relative Ratio Method