datum question
datum question
(OP)
Hi gents,
Please see sketch as attached. In this application, the 2 rows of pin hole serving as datum feature only constrain 2 degrees of freedom. Specifically, during assembly there will be 6 pins inserting half way into the holes. The exposing portions of the pins form the basic distance 112. Part being assembled can slide in between the 2 rows of pins and is stopped by the bottom edge, datum feature C.
In this application, how should I specify datum feature B, option #1 or #2, or something else?
Thanks
Please see sketch as attached. In this application, the 2 rows of pin hole serving as datum feature only constrain 2 degrees of freedom. Specifically, during assembly there will be 6 pins inserting half way into the holes. The exposing portions of the pins form the basic distance 112. Part being assembled can slide in between the 2 rows of pins and is stopped by the bottom edge, datum feature C.
In this application, how should I specify datum feature B, option #1 or #2, or something else?
Thanks





RE: datum question
You can directly tolerance dim 112. This will fall into definition of "irregular feature of size". See ASME Y14.5-2009 Para 4.17, Fig. 4-35
RE: datum question
Why "the above solution" is NOT functionally feasible or cannot be used to show GD and T literacy?
RE: datum question
I think either 120 or 112 has to be reference dimension. Do you agree?
Greenimi,
Your suggestion is very interesting, but I would like to hear others opinion.
RE: datum question
Yes. In fact, 112 may not even be dimension per se, but simply FOS datum designation without numeric value.
Using irregular FOS is relatively new idea, so I believe opinions may split on that one.