Model Scales and Proportions
Most model makers have a good sense of scale and proportion, as evidenced by the models they make. Despite that, some I have talked with don't seem acquainted with common model scales and their uses.
Modern computers and copy machines can facilitate the sizing of drawings in an infinite variation of scales. One can literally size a model to suit oneself. Nevertheless, an understanding of scales can be helpful. Drawings and purchasable models and components are available in specific scales as listed in the accompanying table.
You've probably used a mileage scale on a road map. The same principle applies to ship drawings. Good, recent drawings should have a graphic scale similar to the miles/kilometers scale on a map or should state the scale used to prepare the drawing-visually in the range of 1/32" = l' to 1/4" = l' (column 3 in the table).
Catalogs or lists of models, fittings, and drawings state their scales. Some firms even supply reduced-size copies of their drawings. They can however, be difficult to read or decipher as the lettering and lines grow thinner with each reduction; it's wise to retain readable copies.
Office supply stores and department stores sell triangular or flat architectural or civil engineering rules for measuring and preparing scale drawings. The triangular architect rules include the seven scales noted in the table, plus 3/4", I", 1-1/2", and 2" or 3" = 1', depending on the age of the rule. The flat scales usually have eight scales: 1/8", 1/4", 1/2", I", 3/8", 3/4", 1-1/2", and 3" = 1'. Civil engineering rules are in multiples of 10: 10, 20, 30, 40, 50, and 60 divisions to the inch. Mechanical engineer's scales also exist and are used for drawings that are 1/8, 1/4, and 1/2.
Column 1 of the table lists the ratio of the model or drawing to the actual item. It's best to consider this as a fraction, e.g. 1:2400 = 1/2400, the model or drawing thus being reduced 1/2400th of the original. Scale feet per inch is obtained by dividing the denominator or second number of the ratio by 12. However, several of the model railroad scales are metric-based and do not equate to reasonable fractions of an inch.
Some models are so crowded with details that an error of scale in locating or sizing an item can quickly cause problems. There are also limitations as to physically making some items to scale as they become too difficult to withstand handling. So, fidelity to scale is not always practical, although a general adherence to scale makes a model more accurate.
Some people have a special regard for models that are made "from scratch"-not utilizing any purchased fittings. If a model is built to an unusual scale-not listed in the table-you can reasonably conclude the model was truly scratch-built.
Our cousins outside the USA and UK will likely find the following table amusing as the metric system greatly simplifies their scales.
Common Model and Drawing Scales Scale Ratio
Proportion
|
Scale
|
|
One Scale Foot
|
|
||
Model to-
|
|
Feet in
|
|
Fraction of Decimal- Milligrams |
||
Actual Size RR* One Inch AIE** An Inch
|
Inch
|
Meters
|
||||
1:2400
|
|
200
|
|
1/200
|
0.0050
|
0.127
|
1:1250
|
|
104.2
|
|
-
|
0.0096
|
0.244
|
1:1200
|
|
100
|
|
1/100
|
0.0100
|
0.254
|
1:768
|
|
64
|
|
1/64
|
0.0156
|
0.396
|
1:600
|
|
50
|
|
1/50
|
0.0200
|
0.508
|
1:384
|
|
32
|
|
1/32
|
0.0313
|
0.795
|
1:256
|
|
21.3
|
|
3/64
|
0.0469
|
1.191
|
1:220
|
Z
|
18.3
|
|
-
|
0.0546
|
1.380
|
1:192
|
|
16
|
A
|
1/16
|
0.0625
|
1.588
|
1:160
|
N
|
13.3
|
|
-
|
0.0752
|
1.910
|
1:128
|
|
10.7
|
A
|
3/32
|
0.0938
|
2.383
|
1:120
|
TT
|
10
|
E
|
1/10
|
0.1000
|
2.540
|
1:96
|
|
8
|
A
|
1/8
|
0.125
|
3.175
|
1:87.1
|
HO
|
7.26
|
|
-
|
0.1377
|
3.500
|
1:76.2
|
00
|
6.35
|
|
-
|
0.1575
|
4.000
|
1:64
|
S
|
5.33
|
A
|
3/16
|
0.1880
|
4.775
|
1:48
|
0
|
4
|
A
|
1/4
|
0.2500
|
6.350
|
1:32
|
|
2.67
|
A
|
3/8
|
0.3750
|
9.525
|
1:24
|
|
2
|
A
|
1/2
|
0.5000
|
12.700
|
*RR=Model Railroad Scale **A/EA=Architect's, E=Civil Engineer's Scale Originally published in 70 Ships in Scale * Volume XI, Number 5