Isometric angle

[Cadbuddy]

I'm drawing a mechanical object drawing in isometric.  See 1st image in pic. It requires a 60 degree angle line on both sides of the line. But when I measure the drawn angular line it shows different angle, say 45 or something. How to fix this??

[steven-g]

How are you drawing? the command isoplane and isodraft will lock you into drawing at 60° or are you using some other method?

[Cadbuddy]

In drafting settings, I chose isometric snap, and started drawing. Using acad 2013, don't know whether isodraft work or not..please tell me whether there is a standard method to draw such angles in isometric, refer fig 1 object base

Edited March 16, 2021 by Cadbuddy

[steven-g]

There is an Icon on the lower right of your screen it toggles on/off isodraft, and the drop down arrow just to the right of that will let you pick left/right/top. This tool is designed for creating isometric drawings.

 

 

If for some reason you don't see the Icon, then on the far right of the taskbar you see 3 horizontal lines, click on that and select 'isometric drafting' from the list.

Edited March 16, 2021 by steven-g

[Cadbuddy]

Thanks.. I had that working..but still when I draw 60 degree line and give the angular dimension, it shows something else value, please try to draw yourself and let us know if u get the same issue for isometric

[steven-g]

I get 60° Post a copy of your dwg with the angular dimensions showing so we can see if anything is wrong.

 

[lrm]

@Cadbuddy when creating an isometric drawing you cannot use the "real" angles to draw lines at an angle.  Consider the following.  A cube that has side lengths of 1 would look like the image below.  The red and green lines are diagonals on one face of the cube.  We know that for the real object these lines would be at an angle of 45° relative to the cube's edge.  Look at the real measure angles.

 

For the red "45°" line we measure 1 unit up to the right and then 1 unit straight up. 

For the green "45°" line we measure 1 unit down and then 1 unit up to the right.

 

We know that a 30-60 triangle has sides of 1 and 1.732 (square root of 3) and a diagonal of 2.

 

To draw the 60° line in your isometric measure 1 unit at an angle of 30° then up 1.732 as follow.  Trim the resulting line as necessary.

 

 

 

 

[CyberAngel]

5 hours ago, Cadbuddy said:

I'm drawing a mechanical object drawing in isometric.  See 1st image in pic. It requires a 60 degree angle line on both sides of the line. But when I measure the drawn angular line it shows different angle, say 45 or something. How to fix this??

 

An isometric representation is not really 2D and not really 3D. It's just an illusion of 3D.

 

By convention in an isometric drawing, a horizontal line is drawn at 30 degrees instead of 0. Vertical lines are still at 90. Distances are measured along those axes, so you get some unavoidable foreshortening. That is what's happening in your diagram. If you could build a 3D model and view it from the side, it would have a 60 degree angle. Since it's not 3D and you're not looking at it orthogonally, the angle doesn't appear to be 60. Because this is an illusion, there's no way to measure that angle directly. It's like trying to measure depth in a photograph, you're trying to get three-dimensional information out of two dimensions.

 

Well, Irm ninjaed me, but between the two of us, maybe you can get the idea.

[Cadbuddy]

18 hours ago, lrm said:

@Cadbuddy when creating an isometric drawing you cannot use the "real" angles to draw lines at an angle.  Consider the following.  A cube that has side lengths of 1 would look like the image below.  The red and green lines are diagonals on one face of the cube.  We know that for the real object these lines would be at an angle of 45° relative to the cube's edge.  Look at the real measure angles.

 

For the red "45°" line we measure 1 unit up to the right and then 1 unit straight up. 

For the green "45°" line we measure 1 unit down and then 1 unit up to the right.

 

We know that a 30-60 triangle has sides of 1 and 1.732 (square root of 3) and a diagonal of 2.

 

To draw the 60° line in your isometric measure 1 unit at an angle of 30° then up 1.732 as follow.  Trim the resulting line as necessary.

 

 

 

 

Can you please try to draw the fig 1 and tell us whether your method shows correct angle or not, because it's not showing with me, it would be really helpful!!

[Cadbuddy]

Can you please try to draw the fig 1 and tell us whether your method shows correct angle or not, because it's not showing with me, it would be really helpful!!

[steven-g]

Post the drawing you have, and we can soon see where the problem is. No one is going to do your homework for you, but we will be happy to check to see if there are any problems.

[Cadbuddy]

I'm new to autocad brother, please excuse if I'm mistaken. Please take a look at drawing and tell me what can be done!!

[steven-g]

 I think I see the problem, you are refereing to the 60° shown on the face of the isometric sketch. Yes correct that will never be drawn at 60° in the isometric view. It will only show up properly at 60° on the elevation drawing. The angle is shown there because you need to draw the elevation first in order to get the length of bottom pieces at the base (23.93). That size is the only dimension you are not given and you need to work it out yourself. So yes in isometric the angle will not show as 60° but somewhere about 39° when measured straight on, you cannoy draw using angles in isometric like that.

 

Edited March 17, 2021 by steven-g

[Cadbuddy]

35 minutes ago, steven-g said:

 I think I see the problem, you are refereing to the 60° shown on the face of the isometric sketch. Yes correct that will never be drawn at 60° in the isometric view. It will only show up properly at 60° on the elevation drawing. The angle is shown there because you need to draw the elevation first in order to get the length of bottom pieces at the base (23.93). That size is the only dimension you are not given and you need to work it out yourself. So yes in isometric the angle will not show as 60° but somewhere about 39° when measured straight on, you cannoy draw using angles in isometric like that.

 

 

Edited March 17, 2021 by Cadbuddy

[Cadbuddy]

@steven-g Thanks for clearing my concept!! So when dimensioning how to show angle as 60 in iso??

Edited March 17, 2021 by Cadbuddy

[steven-g]

You can but it is only as information, it will never be accurate. This is one of the few circumstances where I would consider it acceptable to 'overwrite' a dimension which you can do in the properties palette (text override).

[welldriller]

Just a thought but i find it easier to type it in the command bar. Forget the sample thing below. Caint find a way to delete it. Now back to what i find easier. Just type in the command bar type @1.8Troada

Ok i give up.

S

am. ple: @1.8Troada

[steven-g]

@welldriller Try using code tags in your reply even just for simple one line commands starting anything in the text reply with '@' will automatically try and find and link to a user name so that they are automatically notified in the site notification alarms.

[lrm]

Here's another way to construct the 60° angle in isometric.

 

Given

Divide the the isometric rectangle up as follows.  The green lines are used to set the slope of the 60° lines noting that the slope is defined as 1.732:1  or 17.32;10  draw a line 10 long in the 30° direction and 17.32 vertically.

Connect the ends of the green lines to make the 60° lines.

 

 

Trim and add the dimension lines.  The red dimensions are the true angles while the white were created by editing the dimension values. 

[welldriller]

Just a thought but i find it easier to type it in the command bar. Forget the sample thing below. Caint find a way to delete it. Now back to what i find easier. Just type in the command bar type @1.8Troada

Ok i give up.

S

am. ple: @1.8Troada