View source for Engineering:Scale ruler

{{Short description|Tool used for measuring at a fixed ratio}}
A '''scale ruler''' is a tool for measuring lengths and transferring measurements at a fixed [[Ratio|ratio]] of length; two common examples are an '''architect's scale''' and '''engineer's scale'''.  In scientific and engineering terminology, a device to measure linear distance and create proportional linear measurements is called a scale.  A device for drawing straight lines is a straight edge or [[Ruler|ruler]].  In common usage, both are referred to as a ruler.

==Architect's scale==
[[Image:Architects scale.jpg|thumb|300px|A triangular architect's scale, made of [[Chemistry:Brass|brass]]]]
An architect's scale is a specialized [[Ruler|ruler]] designed to facilitate the drafting and measuring of [[Engineering:Architectural drawing|architectural drawing]]s, such as [[Engineering:Floor plan|floor plan]]s and Multi-view orthographic projections. 

Because the scale of such drawings is often smaller than life-size, an architect's scale features multiple [[Unit of length|units of length]] and proportional length increments.<ref name = Giesecke/>

For accuracy and longevity, the material used should be dimensionally stable and durable. Scales were traditionally made of wood, but today they are usually made of rigid [[Chemistry:Plastic|plastic]] or [[Chemistry:Aluminum|aluminum]]. Architect's scales may be flat, with 4 scales, or have a 3-lobed cross-section, with 6 or 12 scales.

===United States and Imperial units===
In the {{wipe|United States}}, and prior to metrication in {{wipe|United Kingdom}}, {{wipe|Canada}} and [[Place:Australasia|Australasia]], architect's scales are marked as a ratio of x [[Inch|inch]]es-to-the-foot (typically written as ''x''″=1′-0″). For example, one inch measured from a drawing with a scale of "one-inch-to-the-foot" is equivalent to one foot in the real world (a scale of 1:12)....one inch measured from a drawing with a scale of "two-inches-to-the-foot" is equivalent to six inches in the real world (a scale of 1:6).  It is not to be confused with a true unitless ratio. A 1:5 architectural scale (inches to feet) would be a 1:60 unitless scale (inches to inches) since there are 60 inches in 5 feet.

Typical scales used in the United States are:<ref name = Giesecke>{{Cite book |title=Technical drawing |date=1997 |publisher=Prentice Hall |isbn=978-0-13-461971-2 |last1=Giesecke |first1=Frederick E. | last2 = Mitchell | first2 = Alva | last3 = Spencer | first3 = Henry Ceicil | last4 = Hill | first4 = Ivan Leroy | last5 = Dygdon | first5 = John Thomas | last6 = Novak | first6 = James E. | last7 = Lockhart | first7 = Shawna |edition=10th |location=Upper Saddle River, NJ | pages = 62&ndash;64 }}</ref>

: full scale, with inches, divided into sixteenths of an inch

The following scales are generally grouped in pairs using the same dual-numbered index line (one scale is read from the right, and the other scale is read from the left):
:{|
|-
|three-inches-to-the-foot (3″=1′-0″) (ratio equivalent 1:4){{pad|2em}}||one-and-one-half-inch-to-the-foot ({{frac|1|1|2}}″=1′-0″) (1:8)
|-
|one-inch-to-the-foot (1″=1′-0″) (1:12){{pad|2em}}||one-half-inch-to-the-foot ({{frac|1|2}}″=1′-0″) (1:24)
|-
|three-quarters-inch-to-the-foot ({{frac|3|4}}″=1′-0″) (1:16){{pad|2em}}||three-eighths-inch-to-the-foot ({{frac|3|8}}″=1′-0″) (1:32)
|-
|one-quarter-inch-to-the-foot ({{frac|1|4}}″=1′-0″) (1:48){{pad|2em}}||one-eighth-inch-to-the-foot ({{frac|1|8}}″=1′-0″) (1:96)
|-
|three-sixteenths-inch-to-the-foot ({{frac|3|16}}″=1′-0″) (1:64){{pad|2em}}||three-thirty-seconds-inch-to-the-foot ({{frac|3|32}}″=1′0″) (1:128)
|}
Add History

===Metric units===
Architect's scale rulers used in Britain and other [[Metric system|metric]] countries are marked with [[Ratio|ratio]]s without reference to a base unit. Therefore, a drawing will indicate both its scale (ratio) and the unit of measurement being used.

In Britain, and elsewhere, the standard units used on architectural drawings are the [[International System of Units|(SI) units]] [[Millimetre|millimetre]]s (mm) and [[Metre|metre]]s (m), whereas in France [[Centimetre|centimetre]]s (cm) and metres are most often used.

In Britain, for flat rulers, the paired scales often found on architect's scales are:
{{colbegin}}
*1:1/1:10
*1:5/1:50
*1:10/1:100
*1:20/1:200
*1:1250/1:2500
{{colend}}
For triangular rulers, the paired scales are:
{{colbegin}}
*1:1/1:10
*1:2/1:20
*1:5/1:50
*1:100/1:200
*1:500/1:1000
*1:1250/1:2500
{{colend}}
Less common scales are:

*1:25/1:250
*1:33{{frac|3}}
*2:1

In France, in engineering departments or architectural offices, here are some scales used :

* 1:100 / 1:300
* 1:200 / 1:400
* 1:250 / 1:500

{{anchor|EngineersScale}}

==Engineer's scale==
[[Image: G Turnbull - box of scales 1857.jpg|thumb|right|Boxed set of 1850s ivory engineer's scales presented to the railway civil engineer George Turnbull in India. 16 scales are engraved.]]
An '''engineer's scale''' is a tool for measuring distances and transferring measurements at a fixed [[Ratio|ratio]] of length. It is commonly made of [[Chemistry:Plastic|plastic]] or aluminum and is just over {{convert|300|mm|in}} long, but with the only 300&nbsp; mm of markings, leaving the ends unmarked so that the first and last measuring ticks do not wear off. It is used in making engineering drawings, commonly called [[Blueprint|blueprint]]s, blue lines, or plans on a specific scale. For example, "one-tenth size" would appear on a drawing to indicate a part larger than the drawing on the paper itself. It is not to be used to measure machined parts to see if they meet specifications. 

In the {{wipe|United States}} this scale is divided into decimalized fractions of an [[Inch|inch]] but has a cross-section like an equilateral triangle, which enables the scale to have six edges indexed for measurement. One edge is divided into tenths of an inch, and the subsequent ones are directly marked for twentieths, thirtieths, fortieths, fiftieths, and finally sixtieths of an inch. Referred to as 1:10, 1:20, 1:30,1:40, 1:50 or 1:60 scale.<ref>{{Cite book |last=Ghilani |first=Charles D. |title=Elementary Surveying: An introduction to Geomantics |publisher=Pearson |year=2018 |isbn=9780134604657 |edition=15th |location=New York |pages=466}}</ref> Typically in civil engineering applications, 1:10 (1″=10′) is used exclusively for detail drawings.  1:20 and 1:40 scales are used for working plans.  1:60 is normally used only to show large areas of a project.

In 1918 French described the US engineer's scale using the term "civil engineers' scale", and it was said to be "used for plotting and map drawing, and the graphic solution of problems."<ref>{{cite book |url=https://books.google.com/books?id=6R5DAAAAIAAJ&pg=PR3 |page=9 |title = A Manual of Engineering Drawing for Students and Draftsmen |last1 = French |first1 = Thomas E. |edition = 2nd |publisher = McGraww-Hill |location = New York |date = 1918}}</ref>

== See also ==
* [[Engineering:Technical drawing tool|Technical drawing tool]]s
* Gerber Variable Scale

==References==
{{reflist}}

==External links==
*[http://www.aaadrafting.com/drafting-tools-techniques/engineeringscales.html Engineering and Architectural Scale Information]

{{Measuring and alignment tools}}

[[Category: Metalworking measuring instruments]]

{{Sourceattribution|Scale ruler}}