datum definition, pattern of holes
datum definition, pattern of holes
(OP)
quick question for you GD&T gurus out there.
I am working on a part that has two dowel pin holes used for alignment of a part.
I think it is possible to define the two holes as a pattern and then define the pattern as a datum to define secondary and tertiary datums to be used for location of other features.
So the datum axis is centered between the two holes (according to ASME Y14.5-1994 section 4.5.8), secondary datum coincides with the axes of each hole, and tertiary intersects secondary at the datum axis and is perpendicular to primary and secondary.
I have not done something like this before but it seems reasonable and mirrors part function. Anyone see any problems with this?
Will post image/link ASAP for clarity.
Thanks!
JoeBK
I am working on a part that has two dowel pin holes used for alignment of a part.
I think it is possible to define the two holes as a pattern and then define the pattern as a datum to define secondary and tertiary datums to be used for location of other features.
So the datum axis is centered between the two holes (according to ASME Y14.5-1994 section 4.5.8), secondary datum coincides with the axes of each hole, and tertiary intersects secondary at the datum axis and is perpendicular to primary and secondary.
I have not done something like this before but it seems reasonable and mirrors part function. Anyone see any problems with this?
Will post image/link ASAP for clarity.
Thanks!
JoeBK





RE: datum definition, pattern of holes
RE: datum definition, pattern of holes
link
RE: datum definition, pattern of holes
RE: datum definition, pattern of holes
There is also a high quality PDF you can view/download that can be viewed, panned, and zoomed easily.
Hope this helps!
RE: datum definition, pattern of holes
RE: datum definition, pattern of holes
RE: datum definition, pattern of holes
You have the part fully constrained in all degrees of freedom. Why aren't you just calling out the features and patterns WRT A, B, and C? It appears that this will accomplish the same objective without the extra datum.
Powerhound
Production Supervisor
Inventor 11
Mastercam X
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: datum definition, pattern of holes
RE: datum definition, pattern of holes
Powerhound
Production Supervisor
Inventor 11
Mastercam X
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: datum definition, pattern of holes