Imperial scale question

[Anonymous]

I've always been working in metric scale until recently, and i just learned that where i work for the imperial scale they use 1"=1", 1"=2", 1"=4", 1"=8", 1"=12", I've been wondering if that was a good way to scale a drawing because i've never seen a drawing like that before and i questionned them where they took this method and they didn't know, so i did my research on internet and ive only seen that for imperial scale it's 1"=1'0", 1/2"=1'0", 1/32"=1'0", and 1"=4", 1"=8", 1"=12", 1"=16", etc, and when i told them they said this is in architectural drawing, not engineering. So does anybody who use the imperial scale for mechanical engineering drawings very often can tell me what is the CORRECT way to scale a drawing please? 

Thank you for your replies.

[john.vellek]

Hi @Anonymous,

I see that you are visiting as a new member to the AutoCAD forum. Welcome to the Autodesk Community!

Yes, architectural scales typically work inch:feet such as 1/8"=1'-0" I have seen mechanical scales typically like 1:1, 1:2, 1:4 etc.

the reason for the difference would be the size of what you are trying to show/display.

Please select the Accept as Solution button if my post solves your issue or answers your question.

[scot-65]

Architectural units can be described as follows:
A unit of one (1) is one INCH.

For Engineering:
A unit of one (1) is one FOOT.

Why?
Expressing the dimension styles in decimal-foot
format requires a unit of one to be one foot (when
DIMLFAC is 1.0). It has always been this way.

Is it the same concept as the Meter verses Millimeter verses Kilometer?

As a test, command DIST and select two points for a known distance.
Example: A 36 inch wide door.
If the return value is 36" or 3'-0" or 3', then it is Architectural.
If the return is 3.0, then it is Engineering.

Look at DIMLUNIT and DIMPOST for possible hints.
Architectural has DIMPOST set to nil "." or inch (").

I will make an educated guess that the Mechanical trade will
use the inch method. Civil engineers use the foot method.

Tape measures in decimal-foot are hard to find around here.

???

[Anonymous]

Thanks for your reply, i think you mean a unit of one is one INCH in engineering and 1 foot in architectural, i've never measured something in foot and always in inch, for my DIMLFAC it's set at 35.000, DIMLUNIT is at 2.000 and DIMPOST at "", but i have no idea what they mean. my question was more about the sacle factor, not the unit i should use, as in do type a scale of 1:4 or 1:8 when i want to zoon in 4x and 8x or should i use 3"=1'0" or 8"=1'0" like 3" measured equal to 1 foot in reality, or if i should use 1/4"=1" or 3/4"=1"?

They means pretty much all the same but i know that in inch=foot it's more architectural but i've seen on internet that a lot of people use it for ingineering too, i've seen some use inch=inch too, more in ingineering and never in architectural and 1:4 is the system we are using, i want to know which one is used the most and if the one we are using is wrong.

[jackshield]

scot-65 is 100% correct in his statement

but to address your post more directly, look at an archtectual scale, you have 3 sides with 6 scales,

if you find it necessary to list scale on your drawing because you think someone may to do physical measurements on it, stick with those scales, makes life easy for everyone.

i do mechanical design and drafting, i do not list scales because i dont want anyone trying to extract dimension from a print.

[Anonymous]

I know he is correct, but in every drawing you make you should put the scaling of the view and the general scaling of the drawing, at least in detail mechanical drawings. I'm totally aware that nobody should measure directly on the drawing and these days i think nobody will measure in the drawing but it's to tell the reader how big this part should be.

I don't know what kind of drawing you're doing but personnally, i've (almost) never seen a drawing without a scale so it can't hurt to know what is the "right" and the "bad" way to call the scale.

[dgorsman]

---

@Anonymous wrote:

if you find it necessary to list scale on your drawing because you think someone may to do physical measurements on it, stick with those scales, makes life easy for everyone.

i do mechanical design and drafting, i do not list scales because i dont want anyone trying to extract dimension from a print.

---

Anything that's important should have a dimension with an actual number, there should be no call for manually measuring it.  If it doesn't have a number, it's not important and scaling off the drawing has an "acceptable" level of error.  Or someone's getting billed for an RFI (request for information) and possible an FCN (field change notice).

[JDMather]

---

@Anonymous wrote:

.... 1"=1", 1"=2", 1"=4", 1"=8", 1"=12".

....anybody who use the imperial scale for mechanical engineering drawings very often can tell me what is the CORRECT way to scale a drawing please?

---

Yes, these are typical scales used on a mechanical drawing, but I am used to seeing them in the title block in the format

1:1

1:2

1:4

1:8

1:12 not so much

2:1

3:1

4:1

for tiny parts and detail views.

I should emphasize that the geometry itself is ALWAYS done 1:1 and then shown at appropriate paperspace scale to fit sheet.

[gotphish001]

Yes I agree with JD. The " mark in the 1":1" isn't usually used. Just 1:1 is used. The " is overkill. They only use inch and feet marks in architectural because things can be scaled to match how screwed up imperial is compared to metric. Like 1 1/2" = 1'-0" which if you said that how mechanical drawings are scaled it would be 1.5:12 which is a little more confusing and is why in mechanical they wouldn't do that. Mechanical is just scaled linear like 1:1, 1:4. No 1.5:4 or goofy scales.

[jackshield]

to my point, if there is a missing dimension, i have failed my job.

i omit scales to subvert any attempts at manual scaling.

i state this from a perspective of equipment tooling and design

[Anonymous]

Thank you for the answers, i've always used 1:1, 1:2, 1:4, 1:5, 1:10, 1:20, etc as scales but when i've been told 1:5, 1:10 and 1:20 is metric and imperial should be 1:4, 1:8 i was really surprised so when i looked on the internet i couldn't see anything about it, even in my mechanical drawing books from school.

[ArchD]

Showing it as 1:1, 1:2, 1:20 implies a ratio which is what metric is. 

Showing it as 1"=1', 1"=2', 1"=20' means that 1 inch equals so many feet. 

If you see it as 1/8"=1" or 1/4"=1' type, that would be more for smaller scales used many times in architectural and mechanical. Civil uses larger scales that typically start off with at least 1"=1' and go up to 1"=2000' or more.

If I don't see the X"=X' format, I'm going to assume that it is scaled as a ratio and assume it's metric.

[JDMather]

---

@Anonymous wrote:

.... even in my mechanical drawing books from school. 

---

The attached image is from Giesecke, et al. Technical Drawing with Engineering Graphics 15th ed.

I have been using this book for around 40 yrs.  The original 1st ed was published before I was born (60 yrs ago).

Note that this portion of the information is related to machine (mechanical) drawings.

I snipped out information on architectural and map drawings.