ISO datum scheme
ISO datum scheme
(OP)
I have a part with ISO standard, please see the attached for details.
There are a lot problems on this drawing, let's concentrate on the datum setup scheme. Have you ever seen this G-H reference datum before? G and H is two holes feature located at the corner diagonally, I believe it would be two hole pattern as a datum in ASME standard, how do you think.
Thanks for your inputs
There are a lot problems on this drawing, let's concentrate on the datum setup scheme. Have you ever seen this G-H reference datum before? G and H is two holes feature located at the corner diagonally, I believe it would be two hole pattern as a datum in ASME standard, how do you think.
Thanks for your inputs





RE: ISO datum scheme
Datum letters separated by dash mean neither takes a precedence just like in ASME (Some ISO experts may be able to point out subtle differences though)
RE: ISO datum scheme
I can find out lot of examples with multiple datum features in 1994 or 2009 standard, I know what is the
meaning of datum feature reference letters separated by a dash, sorry for I didn’t clearly specify
my question.
How will you setup the DRF on the position callout |pos|0.04|G-H|, is this legal in ISO standard?
Season
RE: ISO datum scheme
http://files.engineering.com/getfile.aspx?folder=e...
Of course I assume that no diameter symbol before 0.04 is just a typo.
RE: ISO datum scheme
Season
RE: ISO datum scheme
I am afraid that this issue is just a tip of the iceberg.
I am looking at datum feature C and I don't envy you.
RE: ISO datum scheme
The concept of a common datum establishing from two parallel cylinders is just looks like a two hole pattern as datum feature in ASME, am I right?
Season
RE: ISO datum scheme
RE: ISO datum scheme
In the ISO 5459 excerpt, the two associated cylinders have variable diameters. Would you say that the two diameters are individually variable, or that they must vary together?
Evan Janeshewski
Axymetrix Quality Engineering Inc.
www.axymetrix.ca
RE: ISO datum scheme
Here is different figure from this standard. I believe I know what you are thinking about
http://files.engineering.com/getfile.aspx?folder=f...
RE: ISO datum scheme
Yes, that's it.
Do you think that the two cylinders can be fitted (i.e. minimized) in a unique way? It always seemed to me that there is more than one solution.
Evan Janeshewski
Axymetrix Quality Engineering Inc.
www.axymetrix.ca
RE: ISO datum scheme
RE: ISO datum scheme
It does seem that different common axes could be generated. One simulator could be loosened and the other simulator tightened, resulting in a different relationship between the part and the datum axis.
Evan Janeshewski
Axymetrix Quality Engineering Inc.
www.axymetrix.ca