Inspection Dimensions

[drawoh]

I am designing a completely non-orthogonal mount. I need to prepare an orthogonal drawing, specify dimensions and tolerances, and work out some way to inspect it. I have a bunch of non-critical features the fabricator will have to make accurately so that they can reach the stuff I do care about.

I am surprised at what SolidWorks is letting me get away with. I have created section views at specified orthogonal positions, and I have shown the critical cut-away geometry as reference dimensions. From this, I cam make inspection fixtures. Originally, I showed the inspection dimensions as basic.

SolidWorks has an "inspection dimension" indicator, but this conforms to no dimension specification I am aware of.

Does the attached drawing look reasonable? This is being prepared to ASME Y14.5M-1994, and dimensions are in millimeters. Has anyone else ever had to do this?

--
JHG

 

[Belanger]

A couple of oddball suggestions:

On an actual drawing, you'd want to place the top view above the front view, and the bottom view below the front (assuming 3rd-angle projection; reverse my suggestion if doing 1st-angle projection). The rear view would then hinge off of top or bottom or side.

Add a diameter symbol in front of the zeros in the position callouts.

As for "inspection dimension," I think that hearkens back to "critical dimension" -- neither of which has a standardized definition. See this earlier thread about critical dims:
[URL unfurl="true"]http://eng-tips.com/viewthread.cfm?qid=322065[/url]

I would avoid that thing called inspection dimension unless there is a note or a company document that spells out what it really means for an inspector.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[greenimi]

Question: Angularity 0.1 to A, B and C and profile 0.8 to A, B and C, can be safetly replaced by composite profile: upper segment PLTZF 0.8 to wrt A, B and C, and FRTZF 0.1 to wrt A, B and C. Does it say the same thing? Same mathematical definition?
Thank you

 

[MintJulep]

If I had this drawing and a part I think I could inspect it.

If you handed me this drawing and said "make this"...

 

[Belanger]

Greenimi -- yes. In a composite profile FCF, any datums on the lower tier are understood to be for orientation only, so it would indeed equate with angularity.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[greenimi]

JP
Thank you

Was just a little bit weird to see orientation control above the location control. You locate first and then you orient a feature (if needed). Syntactically correct, just a strange way to dimension and tolerance those features.

 

[fcsuper]

drawoh,

To your comment "non-critical features the fabricator will have to make accurately so that they can reach the stuff I do care about" - anything that needs to be made accurately is critical. This is why I really don't like the word "critical" when talking about dimensions. Technically any feature added to a part should have a purpose, any dimension or other means of control for that feature is critical to define the feature for its purpose.

To the comment "SolidWorks has an "inspection dimension" indicator, but this conforms to no dimension specification I am aware of." - this is an industry practice that is not defined in any standards. As far as I know (please correct me if I'm worng), neither ISO or ASME currently have symbols that delinate inspection requirements. The racetrack symbol is one of two common industry practices. The other is to identify dimensions and other annotations with bubbled numbers which are referred to by an inspection report.

Matt Lorono, CSWP
Product Definition Specialist, DS SolidWorks Corp
Personal sites:
Lorono's SolidWorks Resources & SolidWorks Legion

 

[drawoh]

Greenimi -- yes. In a composite profile FCF, any datums on the lower tier are understood to be for orientation only, so it would indeed equate with angularity.

I never thought of that. I always put the tight one first. On this part, orientation is critical, location very much less so.

--
JHG

 

[drawoh]

A couple of oddball suggestions:

On an actual drawing, you'd want to place the top view above the front view, and the bottom view below the front (assuming 3rd-angle projection; reverse my suggestion if doing 1st-angle projection). The rear view would then hinge off of top or bottom or side.

Add a diameter symbol in front of the zeros in the position callouts.

As for "inspection dimension," I think that hearkens back to "critical dimension" -- neither of which has a standardized definition. See this earlier thread about critical dims:

http://eng-tips.com/viewthread.cfm?qid=322065

I would avoid that thing called inspection dimension unless there is a note or a company document that spells out what it really means for an inspector.

My view labels are completely arbitrary. They reflect how the thing is oriented when installed. Usually, I don't label views, but this time I want to reference stuff in my notes.

I said "inspection dimension" in my post. I deliberately did not use the terminology on the drawing. I am trying to see if there is terminology.

I participated in the critical dimension discussion. On my current drawing, I need accurate fabrication of the faces called up on Views[ ]BB and[ ]CC. The rest of it does not need to be accurate, and I have specified accordingly. The fabricator will have to control several features, particularly the angles on the TOP view and View[ ]AA, both of which I specified sloppily.

In theory, our inspector could find that my Views[ ]BB and[ ]CC features pass, and that the other angles are barely within specification, but in reality, this is unlikely.

Thanks.

--
JHG