Scott H. Haycock
Bill's explanation was hard for me to follow, and I know the trick. I'll try to explain it by example.
I took an HO boxcar off my layout and, using a ruler, measured a side ladder. The top rung is 1-9/32". or 1.28125" from the bottom rung, center to center. There are 7 rungs in the ladder. 7 rungs means 6 spaces between rungs. The spacing between rung works out to .2135", an inconvenient measurement!
For this to work, you want to use a measurement that is less than the total (1.28125''). 6 times 3/16" equals 1.125", a lesser number.
Now, Take a piece of paper and draw 7 parallel lines, 3/16" apart. Take a piece of cardstock, and make a pair of small marks 1-9/32" apart along one edge. Align the bottom mark on the cardstock, with the bottom-most line.Rotate the card so that the top mark lines up with the top line. This is where the angle comes in. Now all the other lines can be marked on the card, and they will be evenly spaced.
This is easier to do, than explain. Try it with my numbers, then you'll grasp the concept.
OK, I’m always grateful to learn new tricks, but this one I do not follow. Bill - what is the advantage you are gaining with the diagonal lines? I do not see how drawing equally spaced marks on the diagonals is easier than doing so on the vertical line? Clearly I’m missing something. Can you explain.