Scaling: Decimal, Architectural, Engineering

[palmeleven]

Hi all, 

I'm running into issues with AutoCAD and am having a hard time wrapping my mind around scales and units so I'd appreciate a detailed explanation and some patience reading this!

 

I have one drawing with the units set to feet in decimal. Whenever I draw a line and specify the length in units, say, 20, for example, there is a line on my screen that reads "20" without units. The units in the settings are set to feet. 

I then change over to engineering and click the line again, it now says 1'-8" in the properties section.

So my question is, why does AutoCAD initially interpret my input as inches even though the units are set to decimal and feet?

 

Conversely, I'm also working on a file that was drawn in engineering/architectural, the dimensions all show up correctly (feet and inches) and they make sense.

However, when I draw an alignment and look at the station values and offsets, the stations measure every 100 inches instead of every 100 feet. 

So I'll create a dimension callout between 2 stations that are supposed to be 100 feet apart, and the measurement will read 8'-4".

I'll go over to the alignment properties and it tells me that the stations are 100 feet apart (with the ' tick to indicate feet), yet the dimension I drew between the stations reads 8'-4".

 

I feel like I'm misunderstanding something at a fundamental level because it's confusing to see inches treated as feet and vice versa on one drawing without me changing anything. 

Thank you in advance for your answer(s).

[ReMark]

Because 20.0 decimal is the same as 1"-8" architectural.  Architectural units differ from Decimal units.  For example, nine and one-half inches in architectural (feet/inches) units would be displayed as 0'- 9 1/2" whereas in decimal units it would be displayed as 0.7916'.  Here is a chart comparing the two units.

  

[palmeleven]

The issue is that in decimal, it doesn’t display as 0.7916, it displays as a unitless 20 and my drawing is set to ft in the units settings 

[palmeleven]

53 minutes ago, ReMark said:

Because 20.0 decimal is the same as 1"-8" architectural.  Architectural units differ from Decimal units.  For example, nine and one-half inches in architectural (feet/inches) units would be displayed as 0'- 9 1/2" whereas in decimal units it would be displayed as 0.7916'.  Here is a chart comparing the two units.

  

 

The issue is that in decimal, it doesn’t display as 0.7916, it displays as a unitless 20 and my drawing is set to ft in the units settings 

[ReMark]

You said you were working in decimal units.  Note: AutoCAD is, by its very nature, unitless meaning one can equal anything from one inch to one parsec (a unit of distance in astronomy) and everything in-between.  Did you go into your Dimension Style and set the Primary Units to decimal?  BTW... if for some reason you wish to display two different sets of units, feet/inches & metric for example, you would have to go into your Dimension Style and set it up via the Alternate Units tab.  Example:

 

Edited September 10, 2022 by ReMark

[SLW210]

Sounds like you are drawing in inches. UNITS would not be the correct method of setting drawing units. You need to set the drawing units with -DWGUNITS.

[palmeleven]

My drawing is set to engineering

I have drawn an alignment that, according to the properties bar, spans 1,300'

I then create a dimension between the start and end of the alignment, and the dimension displays 108'-4"

How is the length of that alignment interpreted by autocad as both 1,300 feet and 1,300 inches?

[CyberAngel]

24 minutes ago, palmeleven said:

My drawing is set to engineering

I have drawn an alignment that, according to the properties bar, spans 1,300'

I then create a dimension between the start and end of the alignment, and the dimension displays 108'-4"

How is the length of that alignment interpreted by autocad as both 1,300 feet and 1,300 inches?

As ReMark pointed out, AutoCAD does not define the type of units in a drawing. When there's an inconsistency, it's in the presentation. Change the type of unit your dimension displays, and the text will change with it.

 

The length of the alignment, as shown in the Properties window, is correct, because it's using feet. The length, as shown in the dimension, is correct, because it's using inches. Yes, it's confusing. I've worked with architects, who use inches, and engineers, who use feet, and it can get problematic.

 

If you have to work with different drawings at different scales, try inserting one into another as an external reference. That way you can set the scale once, make sure the drawings correspond, and you're done.

 

[palmeleven]

1 hour ago, CyberAngel said:

 

 

The length of the alignment, as shown in the Properties window, is correct, because it's using feet. The length, as shown in the dimension, is correct, because it's using inches. Yes, it's confusing.

 

 

 

Creating an x-ref scaled down by 12 is the only solution I've come up with so far, but it's still confusing to have AutoCAD state that the same line segment is 2 different lengths. I guess my question is -- why are my alignment and dimension style using different units to interpret what a unit is? Should they not agree with each other on the distance of one unit foot? If my alignment is using feet to display the length and the dimension is using inches -- shouldn't they display 108'-4" and 1,300", respectively?

[tombu]

In Dimension Editor on the [Primary Units] tab I add ' as the Suffix and add an Angular child style with the Suffix removed so 1.5 dimensions as 1.5'.

I also include Architectural styles which on the [Primary Units] tab I add a Scale factor: of 12 and set Linear Unit format to Architectural with 1/4" precision for dimensioning structures in inches so 1.5 dimensions as 1'-6". 

The Architectural styles are mostly used to dimension typical Structures like manholes and drainage inlets.

[SLW210]

If your dimensions are wrong, you need to set the appropriate dimension style to show the correct dimensions, scaling is not a solution.

 

Can you post a drawing?