×
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

Datum in a second view

Datum in a second view

Datum in a second view

(OP)
The question I have is if a datum is identified in one view as the centerline of a "feature of size", how might I identify that centerline in another view?  In the second view the centerline is the starting point for a half dimension and the datum feature is not visible.

Yes, I realize that GD&T would use possibly a profile callout or a TP callout instead of the half dimension. My problem is that I do not have the influence to mandate a chamge to GD&T.  I would like to start by properly identifying datums. Currently, a datum symbol may be attached to a centerline that has 5 coincidental features and there is no way to know which feature truly is the datum.  

I would put the conventional datum symbol in line with the FOS dimension line in the first view but what do you do in the second view?

Thanks in advance  

RE: Datum in a second view

Does your drawing state in accordance with A.S.M.E. Y14.5?

Are you familiar with Y14.5?

A datum identifier CANNOT BE APPLIED to a centerline.  It must be associated with the FOS.

RE: Datum in a second view

(OP)
No, it does not state ASME Y14.5  
I am afraid that I used to be and now I am out of date with the current standard.

In the older revisions the datum "flag" could be attached to a centerline, identifying a centerline that may have been described by tooling points in another view.  would this practice still be acceptable?

Thanks,
Vegabond

RE: Datum in a second view

You can identify a centerline as a datum axis in another view.  It is against the standard to identify a centerline as a datum without adding "axis" or "centerline" to the callout.

RE: Datum in a second view

(OP)
Thanks for the reply, It is not clear to me what you mean by: Adding Axis or Centerline to the callout.  If the datum symbol is in line with the "feature of size" dimension, ref FIG 3-4 pg 43 yi4.5, we already know that the Center is the datum in the first view.  Are you talking about the callout in the second view?

RE: Datum in a second view

Yes, I was refering to any subsequent callouts of that datum.

RE: Datum in a second view

It would seem that to properly address your problem one would need to know the drawing standard being applied.

RE: Datum in a second view

Vegabond,

If the datum feature is a feature of size, the datum feature symbol is attached to or associated with the size dimension.  By attaching or associating the datum feature symbol with a particular size dimension, it defines a specific point, axis or median plane that is derived from that feature as the datum.

Best Regards,

Heckler
Sr. Mechanical Engineer
SW2005 SP 5.0 & Pro/E 2001
Dell Precision 370
P4 3.6 GHz, 1GB RAM
XP Pro SP2.0
NIVIDA Quadro FX 1400
      o
  _`\(,_
(_)/ (_)

"Coming together is a beginning, staying together is progress, and working together is success." - Henry Ford



 

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