Location and orientation 1

[Sa-Ro]

Hi

Doubt 1:

Design requirements:
1) SURF A location from datum A shall be 0.2.
2) SURF A parallel to datum A and perp to datum B is 0.04.

Which of the below method is correct?

1) composite profile.
First segment: 0.2|A|B-max
Second segment: 0.04|A|B-max

2) Multiple segment.
First segment: profile of surface|0.2|A|B-max
Second segment: Angularity|0.04|A|B-max
----------------------------------------
Doubt 2:

Design requirements:
1) All surfaces location shall be 0.2.
2) All surfaces location orientation is 0.04.

Which of the below method is correct?

1) composite profile.
First segment: 0.2|A|B
Second segment: 0.04|A|B

2) Multiple segment.
First segment: profile of surface|0.2|A|B
Second segment: Angularity|0.04|A|B

Thank you.

 

[3DDave]

In the first example the reference to datum feature A overrides any contribution to orientation relative to datum feature B.

If you want them separate then have one related to datum feature A and a second one related to datum feature B.

Composite won't apply because that only controls multiple features to each other and there is only one feature being controlled.

In the second example composite will work for controlling orientation, but I think it will eliminate the zone allowed for the first rather that refining orientation.

The use of multiple segments will perform as you wish.

 

[Sa-Ro]

Thank you.

 

[Burunduk]

Sa-Ro,

"Doubt 1":
SURF A has a location relationship with only datum A.
In addition, datum A as a primary datum reference constrains the 2 rotational degrees of freedom which have relevance to SURF A.
Therefore, datum feature B is not necessary. If the orientation to datum B is required to be controlled directly, specify a separate perpendicularity control.
Both options: 1. composite profile (which can be applied either to a single feature or to a pattern) and 2. * separate profile and orientation feature control frames one attached to the other - will work with only A referenced. For option 2, parallelism can replace angularity, which is more straightforward for a single datum reference to which there is only a parallel orientation relationship.

"Doubt 2":
Two of the four grouped surfaces controlled by all-around profile have a location relationship to datum B, provided there is a basic dimension added to your sketch.
Also, the |A|B| datum reference frame constrains 3 rotations and defines the orientation of all the controlled surfaces.
So, for the composite profile option, the first segment will only control the location of the right-hand and left-hand surfaces in the right-left direction of translation. The form, orientation, and mutual location per basic 50 and basic 15 (size when you treat it as a single feature) of all the grouped surfaces will be controlled by the second segment.
The second option: * profile and angularity separate feature control frames placed adjacent one beneath the other, will work in a similar way. separate profile and angularity will not work, because the all-around symbol applies to the profile geometric characteristic only, and since these are essentially separate controls, it will not be clear that the angularity tolerance intends to control the four surfaces as a group. The angularity tolerance will be supposed to be interpreted as applying only to the surface to which the leader points.

* I would probably use the term "multiple angle segment" only where the segments have the same geometric characteristic symbol.

 

[Burunduk]

Sa-Ro,
The below sketch is just to clarify why for your "Doubt 2", the method which you call "multiple segment" wouldn't work. The two options: a. (angularity as a "second segment") and b. (angularity FCF placed separately) have exactly the same meaning. The all-around symbol applies only to the profile control.

 

[Sa-Ro]

mutual location per basic 50 and basic 15 (size when you treat it as a single feature) of all the grouped surfaces will be controlled by the second segment

But second segment will not control location as per standard.

 

[Burunduk]

Sa-Ro,
The location of features relative to the datums is not controlled by the second segment.
The mutual location between surfaces grouped by the all-around symbol is controlled by the second segment (or third where there is one). As I mentioned, you can treat this mutual location as the size of an irregular feature of size formed by the all-around grouping.

 

[Sa-Ro]

Ok. Thank you.

 

[Burunduk]

Similarly,
If you use a composite position on a pattern of holes, the first segment will control the location of the pattern relative to the datums. The mutual location between the holes will be controlled by the second or subsequent segments (along with orientation to the datums for segments in which datums are referenced).

 

[Sa-Ro]

Thank you.

Pattern of holes given in many examples.

But opposed surface example may be less.

I thought feature means, hole, extrude, extrude cut, revolve cut - in 3D model.

Not thought about individual face can be a feature.

 

[Burunduk]

Individual faces are certainly features. A feature is any physical portion of a part or its representation on drawings or models.

 

[Sa-Ro]

Ok. Thank you.