Assistance Translating Feature Control Frame to Layman's Terms 1

[Chaldaean]

Hello All -

Within the attached drawing, there is a feature control frame highlighted in red. Can you please relay, in plain language, what this frame means?

Drawing:

http://files.engineering.com/getfile.aspx?folder=b67967bd-10c0-4350-a0e4-8052407c601a&file=Drill.jpg

Thanks for your time thus far!

Note: I have intentionally deleted some dimensions within the attached file as it is customer owned.

 

[ewh]

At it maximum size (4.05), the axis of the 4.00 dia feature must lie within an envelope of .25 dia about the axis of datum A. At it's minimum size (3.95 dia) it must lie in an envelope of .30 about the axis of datum A.

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]

 

[pmarc]

I would only add one comment to what ewh said:
Envelope (tolerance zone) has got diameter 0.35 not 0.3 when the toleranced feature is at its minimum material condition.

 

[ewh]

Yep, another post I hit submit on before thinking it out completely. Thanks pmarc!

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]

 

[SeasonLee]

For this case, tolerance of position is used to control the coaxiality between features of size.

SeasonLee

 

[Chaldaean]

Great! Thanks for the speedy replies ewh, pmarc and SeasonLee! "Coaxiality" was the word we were trying to think of, but couldn't conjure up!

To recap (just to be sure I'm understanding correctly), since there is an "M" (maximum material condition) in the feature control frame, this denotes that a bonus tolerance is permissible.

AT MMC: The tolerance window is simply as stated in the frame control frame. As stated above, at a 4.05 feature diameter there is a 0.25 dia tolerance window between the axis of the 6.18 feature and the 4.00 feature.

AT LMC: The bonus tolerance comes into play and at a 3.95 feature diameter, the tolerance window is 0.35 in dia. This 0.35 tolerance window is calculated by taking MMC-LMC (4.05-3.95 = 0.10) and adding it to the tolerance stated within the control frame (0.10 + 0.25 = 0.35).

Thanks, again!

 

[pmarc]

Chaldaean,

Yes, you got it correctly.

 

[fsincox]

Does note "C" say anything important?
Frank

 

[Chaldaean]

fsincox, the "C" indicates a critical dimension that must be inspected (per an AQL) at incoming prior to use in the finished assembly.

Thanks for the question.