Contact US

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!

*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




Hello all,

Please help understanding a parallelism of a hole. For example, we have a drawing as below:

In 3D view it can be represent like this:

How I understand that if the axis of a hole is in the cylinder with diameter of 0.02, the piece is acceptable how it is represented in Picture 1.
But a question appear in my mind, how the zone the tolerance is oriented?. In my mind, it can be like Picture 2 (the axis of zone of tolerance is parallel with datum A), please correct if I am wrong.
Thanks a lot in advance for future answers

RE: Parallelism

Parallelism requires a reference to be parallel to. This doesn't have the required reference. This appears to be a mistaken use of the symbol and most likely should have been straightness. Whatever the intended control, the one that is there is not interpretable.

RE: Parallelism

3DDave is correct; you need to reference the datum that the axis is supposed to be constrained to.
You are correct that it only controls parallelism of the axis relative to datum A.

"Know the rules well, so you can break them effectively."
-Dalai Lama XIV

RE: Parallelism

Parallelism, if properly applied, would only control relative to the planar datum, it could move all over the place in the other direction as you have shown. Normally you would use the position control if you want to control a hole relative to two datums.


The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

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! Already a Member? Login


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close