Isometric Views Size

[Anonymous]

I work as a Technical Drawing instructor. At some point I print drawings of isometrics for my students to obtain their measurements with the scaler and draw the views.

However, while using Inventor 2019, the actual scale for the isometric when I print it is not the one selected,

e.g., an isometric view is selected to be 1:1 scale, but when I print it a line that should measure 70 mm measures 57 mm.

I have to multiply the selected scale by a factor of 1.22 in order for it to print in the right size.

¿Does anybody know how to change the set up so this manual multiplication of the scale is not necessary?.

Many thanks.

[Cadmanto]

Welcome to the forum.

If you place a view at 1:1, if you choose full size or a scale of 1:1 in your printer properties, then it should come out as such, 1:1.

Can you post an image of what you are trying to print?

Windows 10 x64 -16GB Ram
Intel i7-6700 @ 3.41ghz
nVidia GTS 250 - 1 GB
Inventor Pro 2018

[Sergio.D.Suárez]

Hi, Check that the printing options show the correct scale, that it is not in the "Best fit"

[Anonymous]

Hi, 

Thanks a lot. 

Sure! Here are some pictures: picture 1 shows real size of model, picture 2, shows scale I had to use to get the right printed size of isometric drawing.

Picture 3 shows printed result when scale 1:1 is used (Incorrect) Picture 4 shows printed result when using 1.22 : 1 scale is used. 

Finally, I'd like to say It does not have anything to do with the printing process, since the same drawing file has some orthographic projections and they don't have the problem.

Kind regards,

1 Real size2 Scaled used in order to get right result3 Printed outcome of 1:1 (Incorrect)4 Printed outcome of 1.22:1 (Correct)

[Anonymous]

Hi, 

Thank you. 

I'm quite sure that's not the problem. I'm already using Model 1:1 when printing.

Besides orthographic views printed from the same document at the same time have the right size.

 Regards,

[Anonymous]

Hi, 

Somehow it shows as if this reply had solved the issue.

I don't know if I accidentally hit the "Accept Solution" Button or if the forum administrador did it. 

But the issue is not solved.

Kind regards.

[johnsonshiue]

Hi Noel,

I think I know where the confusion is. This is about the true length of the 3D edge in 3D or the measurement of the projection in the drawing. You can do the following experiment.

1) Create a cube of 100mmx100mmx100mm.

2) Create a drawing view of the box in isometric view.

3) Dimension one of the non-vertical edges. You will see it reads 100mm. This measurement is taken from 3D geometry.

4) Right-click on the view -> General Dimension Type -> change it from True to Projected.

5) Repeat step3. You will see it reads 81.65mm. This is the measurement you will get on paper.

You cannot have both because the 2D drawing view is a projection of a 3D object. The isometric view is not going to make a 2D view work like a 3D object all of a sudden.

Many thanks!

[Cadmanto]

Ok, I see what you are talking about.  But the one screen shot that is missing and in my opinion is the most important one, is of your print manger before you select the "Print" button.  If your print manager is not set to print 1:1 then these are the type of results you can expect.

Windows 10 x64 -16GB Ram
Intel i7-6700 @ 3.41ghz
nVidia GTS 250 - 1 GB
Inventor Pro 2018

[Anonymous · Accepted solution]

Hi Johnson,

You are totally right, the thing is that there are many ways to represent an Isometric drawing, the traditional uses the same magnitude for isometric views (3Ds) than for orthographic projections (2Ds). Although it is not realistic (we both know the dimensions of an object change when seen in 3D), it was very common in manual drawing (see picture 6). 

On the other side, picture 7 (from the Giesecke in Spanish version) shows a realistic Isometric, where all dimensions are shortened by a factor of (2/3)^(1/2) or almost 80%.

That explains why I have to multiply my scale by 1.22 in order for my 3D drawings to be represented in the traditional way explained before.

Funny thing is Autocad 3D uses the traditional way to represent 3D objects. Because I used to make this exercise for my students using that software and never had the problem I described initially.

Long story short: Inventor uses the realistic approach while making 3D isometric drawings. If you want your 3D isometric drawings to be represented in the traditional unrealistic way you must multiply your scale by (6^(1/2))/2 whic is the 1,224744871 or the 1,22 I calculated experimentally at the beginning.

Picture 5. Not realistic IsometricPicture 6. Realistic Isometric