circular hole pattern as datum
circular hole pattern as datum
(OP)
I know there is a lot of discussion about holes for datums, i think i read them all, still a little confused. I have this part (see pic) that has 4 thru holes that bolts go through and meet up with tapped features on a different part. is the way i have it correctly dimensioned (only talking about the thru holes, datum A is the face the holes are on)? So the virtual condition of all of these holes will be diameter .144", with respect to eachother? The mating part has the tapped features dimensioned with a virtual condition of diameter .144" so i think i am fine. I am trying to understand how to think about it, or how it would be checked. Would you have 4 .144" pins at the basic locations and then see if this part fits over the pins and if it does its ok? Any help would be great. Thanks in advance





RE: circular hole pattern as datum
John Acosta, GDTP Senior Level
Manufacturing Engineering Tech
SSG, U.S. Army
Taji, Iraq OIF II
RE: circular hole pattern as datum
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: circular hole pattern as datum
RE: circular hole pattern as datum
I will just add that the simultaneous requirement will control the mutual relationship between the holes.
The gage pins should be at .150-.002-.004 = .144(virtual boundary / condition)
RE: circular hole pattern as datum
RE: circular hole pattern as datum
RE: circular hole pattern as datum
But based on the title of this thread, I suspect there should be a "4X" on there somewhere. Then I would agree with you guys.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: circular hole pattern as datum
thanks for the catch anywayrs
RE: circular hole pattern as datum
John Acosta, GDTP Senior Level
Manufacturing Engineering Tech
SSG, U.S. Army
Taji, Iraq OIF II
RE: circular hole pattern as datum
On the other hand, the distances among those holes should be specified with certain tolerances instead of basic dimensions, unless you define the center hole as a second datum, 4X holes or one of them as a third datum.
RE: circular hole pattern as datum
John Acosta, GDTP Senior Level
Manufacturing Engineering Tech
SSG, U.S. Army
Taji, Iraq OIF II
RE: circular hole pattern as datum
If Datum A is the bottom face, why is true position being used?
How can Datum A control the holes positions relative to each-other?
What is controlling the angles between the holes, is that just not shown?
RE: circular hole pattern as datum
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: circular hole pattern as datum
What is controlling the angles between the holes, is that just not shown?"
Did i say---few days ago--:"I will just add that the simultaneous requirement will control the mutual relationship between the holes. "
Does not matter the angle, as long as it IS BASIC!!!
RE: circular hole pattern as datum
polarcylindrical coordinates?There is a tolerance zone 4 thou in diameter located at the exact location of the intended points?
What defines the zero orientation for the 45degree angle? is it the same thing?
RE: circular hole pattern as datum
Polar is okay to use here.
More like a .144 diameter boundary but essentially, yes.
Really, the 45 degree should be eliminated and everything else located with respect to the datum established by datum feature A the 4 hole pattern (B).
John Acosta, GDTP Senior Level
Manufacturing Engineering Tech
SSG, U.S. Army
Taji, Iraq OIF II
RE: circular hole pattern as datum
RE: circular hole pattern as datum
John Acosta, GDTP Senior Level
Manufacturing Engineering Tech
SSG, U.S. Army
Taji, Iraq OIF II
RE: circular hole pattern as datum
Y14.5
The drawing should define a part without specifying
manufacturing methods. Thus, only the diameter
of a hole is given without indicating whether it is to be
drilled, reamed, punched, or made by any other operation.
However, in those instances where manufacturing,
processing, quality assurance, or environmental
information is essential to the definition of engineering
requirements, it shall be specified on the drawing or in a
document referenced on the drawing.
RE: circular hole pattern as datum
John Acosta, GDTP Senior Level
Manufacturing Engineering Tech
SSG, U.S. Army
Taji, Iraq OIF II
RE: circular hole pattern as datum