×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Inventor, COG
2

Inventor, COG

Inventor, COG

(OP)
"Using Autodesk Inventor, why does the COG shift off centerline in my model of a pipe when I cut threads into it?" It shifts off center of the center line. A shift length ways I could understand.

RE: Inventor, COG

Because there is a start and end to the thread, and if not perfectly opposed (i.e. symmetric), leads to a slight offset of the c.g. Probably can be ignored for most instances, since the pipe itself is not controlled to a level of symmetry to make the threading offset apparent. The change should be pretty minimal...

RE: Inventor, COG

Is there really a need to include pipe threads in your model?

RE: Inventor, COG

(OP)
That makes sense btruebood, but I can't see it changing the COG as much as it's changing it. It's a dramatic change.
Good logical answer though.

RE: Inventor, COG

The way the COG is calculated (the algorithm) is to project little triangles from the surface of the part onto a plane. If the normal to the triangle is away from the plane the projected volume is added. If towards the plane, it is subtracted. For each volume a CG is calculated. At the end, the volumes and CGs are taken together to generate a net CG for the part.

I would guess that the threads add a huge number of little triangles and there are errors that accumulate.

RE: Inventor, COG

Perhaps it might be better to post this in the Autodesk: Inventor forum.

John R. Baker, P.E.
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

RE: Inventor, COG

post the ipt?
version of Inventor?
up to date on updates/service packs?

And last but certainly not least...
Why are you actually cutting real threads vs just using the cosmetic representation of them?




Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources