How to measure parallelism and perpendiculars lines / planes

[arthur.belanger]

Hello all, I'm new user of Inventor and I am using it to import plane/lines entities and measure them for Reverse Engineering.

I have some planes that are NOT parallel to any plane and some that are parallel and I want to measure the angle between them and make sure which planes are parallel. The angle could be less than 0,0000005 degre. I did not find a way in Inventor but I can do it using solidworks.

When 2 planes are parallel the angle between them is 0,000000000 in Inventor. In solidworks the angle is 0.

When 2 planes are NOT parallel the angle between them is 0,000000000 in Inventor. In solidworks it is 0,0000005 degre (the real value).

Is there a way to know when 2  planes are parallel or perpendicular?

The problem occur with perpendicular planes too, sometimes the angle between 2 perpendicular planes is 90,000000000 instead of the real value (The real value could be between 90,00000000 and  90,00000004 degre)

In the video, I try to measure angle between 2 parallel planes and then I try to measure angle between 2 planes NOT parallel. The result is always 0,000000000 in Inventor.

I can't figure out which planes are parallel.

I'm not sure if it is a bug of me not using the right parameters/function to measure parallel planes.

Please let me know if you have an idea to solve my problem.

Thank you,

Arthur

[blandb]

Can you share an example, typically you can just choose the faces of planes.

[arthur.belanger]

Hello,

Here a session with 4 planes. The first 2 planes are parallel. The last 2 planes are NOT parallel.

Measure angle between 2 first planes and angle between 2 last planes give the same value.

You can watch the video I put in the first comment.

Thank you,

[CGBenner]

@arthur.belanger 
Here are the results I got in 2023...

Are you using the All Decimals option?

[arthur.belanger]

Hi CGBenner,

I got the same value as you, I use the maximal number of decimal for angle precision like you did. I am using Inventor 2023 too.

How do you know if the 2 planes "Plane parallel to plane 4" and "Plane 4" are parallel?

How do you know if the 2 planes "Plane not parallel to plane 2" and "Plane 2" are parallel? (These planes are not)

Angle between "Plane not parallel to plane 2" and "Plane 2" is 0.00000005 deg in Solidworks. 
Thank you,

Arthur

[SBix26]

I think you are depending on calculations at the extreme edge of numeric reliability.  Both SW and Inventor measure them as parallel within any reasonable tolerance.

How do you know that "Plane 2" and "Plane not parallel to plane 2" are in fact not parallel?  You're relying on a mathematical model in one software and deciding that it is the authority.  Perhaps that is a valid decision if the one uses a much higher precision than others that you are evaluating.  But it may simply be that SW is reporting 10th decimal place noise as reality, while Inventor is not, or the other way around.

These modelers use a lot more decimal places than are measurable in the real world precisely so that calculations to useful numbers of decimals are accurate.  If you ask for the last decimal place, you will likely not get consistent and reliable results.

My opinion based on years of experience and observation-- I'm not a mathematician.

---

Sam B

Inventor Pro 2023.1 | Windows 10 Home 21H2

[arthur.belanger]

Hi  SBix26,

I created those entities manually in another 3D software and I know which planes are parallel and which are not. But someday, I will need to use a software like Inventor to know which one is parallel when I will not know. 

I don't want to measure really low angle value, I want to know which planes are parallel.

Maybe I am not using the right function of Inventor, can you help me find the right tool?

Thank you,

Arthur

[Frederick_Law]

On most situation, 0,0000005 deg is considered parallel.  Typical machine shop and production cannot measure that small angle.

Unless you're working on astronomical or atomic scale, it is not relevant.

If you are, you might need specialize software.

We got a job to machine reflector of space telescope.  We need to machine it in constant 20C.

[mcgyvr]

Inventor is simply not possible of dealing with that precision. 

 I suspect something to do with internal units and conversion back and forth between them right at the extreme precision limit of the software. Inventor (measure tool) won't report anything but zero degrees starting around .000057 degrees.. anything smaller and the measure tool reports as 0.0000000

The "parameters" section acts differently and will report lower

ilogic may be different too..