How do I figure out the scale of something? What is the formula? Thanks much...jerry
Hello, and welcome to the forum.
A scale in is worth so many inches in the real world. An inch on a model would represent several inches or even feet in the real world.
It helps to know what the scale is that you are dealing with. In HO, for example. one inch on the model represents 87.1 inches on the real thing. You can appreciate that you can only show so much detail in the one little inch on the model.
-Crandell
Pick up a model railroad scale. They're indispensable.
Remember the day back in grade school in math class when the teacher said that, "...someday you are going to need to know this." Today is that day.
Scales are ratios of something big to something small. They are represented by fractions (HO = 1/87) or numbers separted by a colon (HO = 1:87.1).
To find out how many scale units are in a real unit, you multiply the real units by the scale. To find out how many big in real units so many scale units are you divide by the scale.
For HO the scale is 87.
If you want to know how many HO feet are in 1.5 real feet multiply 1.5 x 87 = 130.5 So that 18" turntable (1.5 ft) is 130.5 HO feet long.
If you want to know how long in real feet 90 scale feet is, divide 90 by 87, 90/87 = 1.03 feet. So the Walthers 90 ft turntable is 1.03 feet long.
The key thing is to get the units right, convert everything to same units (all the examples above were in feet) and prefferably to decimal units (1/2 = .5, 9/16 = .563).
A handy tool is a scale rule (you can buy them from hobby shops).
Dave H. Painted side goes up. My website : wnbranch.com
Look at this NMRA standard for the various model railroad scales (O, HO, S,N etc). It gives the ratio of full size to model size, the track gauge (which is usually different from what you would expect. For instance the Standard gives 1/87, 3.5 mm/ft, and 16.5 mm track gauge for HO.
It is possible to make scale drawings with just a regular ruler. Merely divide the real measurement by the scale factor. For instance, again using HO for example, you divide the real world dimensions by 87 to obtain the HO dimensions. However this can get VERY tedious and the purchase of a scale rule is well worth the modest cost.
If working from photographs, you measure the length of something in the photo that you know with a pair of dividers. For instance doors are 8 feet high, people are about 6 feet high, and freight car wheels are 33 inches. Set the dividers to the known size. Then step off the photo dimension and multiply the number of steps by the size of each step.
David Starr www.newsnorthwoods.blogspot.com