C
Coleman Donnelly
I have a callout on my print that i have never seen before - hopefully someone here can help me interpit what the print means:
True Position Question - What does this print callout mean?
D
Dean Frederickson
Coleman I have looked in both my Geometric Dimensioning and Tolerancing handbooks, I can't find anything that even remotely resembles what you have there. Where is the print from, what country? 
D
David DeLong
I have been training in this subject for over 20 years and certified through ASME in the subject but I can only help you a bit. This certainly isn't to the ASME Y14.5M-94 standard.
I do see a diameter of 26.75 that does have a GD&T callout (maybe positional) that I have never seen before. The primary datum is A with a secondary of B & C (could be correct but I would have to see the drawing) but I have never seen such a modifier on the secondary datum. The tertiary datum is D.
I wish that I could help you more.
I do see a diameter of 26.75 that does have a GD&T callout (maybe positional) that I have never seen before. The primary datum is A with a secondary of B & C (could be correct but I would have to see the drawing) but I have never seen such a modifier on the secondary datum. The tertiary datum is D.
I wish that I could help you more.
N
NCYankee
My best guess is that they are looking for a True Position of 1 mm diameter to datum -A-, and datum -B-. I'm not sure what the circle with the double lines running from the center out the top is meant to mean (possibly a funky way of calling out concentricity), so I can't say for sure about datums -B- and -C-.
The best thing you could do is call the supplier who provided the drawing, or even your own engineering department, who should have reviewed this drawing as part of contract review and/or APQP.
On a humorous note, doesn't the callout for the 1 mm diameter look eerily like Nessie or Champ?
The best thing you could do is call the supplier who provided the drawing, or even your own engineering department, who should have reviewed this drawing as part of contract review and/or APQP.
On a humorous note, doesn't the callout for the 1 mm diameter look eerily like Nessie or Champ?
I have a callout on my print that i have never seen before - hopefully someone here can help me interpret what the print means:
Coleman,
What would helps us:
- Origin of the print (country)
- A copy of the entire print (if permitted)
- Possible standard used (look in the title block)
Otherwise I am lost on those modifying symbols.
We are very, very curious......
Stijloor.
C
Coleman Donnelly
Sorry this picture didn't turn out verry good...
Engineering stardard that print is drawn to is FAD ?
Engineering stardard that print is drawn to is FAD ?
Sorry this picture didn't turn out very good...
Engineering standard that print is drawn to is FAD ?
Coleman,
Still hard to read. Do the modifying symbols (in the circle) look like an "M"?
Don't give up on us, we'll figure it out somehow.
Stijloor.
C
Coleman Donnelly
Yes essentially it looks like this
|(True Positon symbol)|(Diameter symbol)1|A|B(mmc symbol) - C(mmc symbol)|D|
There is now way to import GD&T symbols that i know of for the font style on this forum...
The confusion that i have is the |Bmmc - Cmmc| portion - i have never seen this before... Typicaly i only have A|B|C this one shows A|B-C|D...
Hope this helps explain my problems!
|(True Positon symbol)|(Diameter symbol)1|A|B(mmc symbol) - C(mmc symbol)|D|
There is now way to import GD&T symbols that i know of for the font style on this forum...
The confusion that i have is the |Bmmc - Cmmc| portion - i have never seen this before... Typicaly i only have A|B|C this one shows A|B-C|D...
Hope this helps explain my problems!
Coleman,
That makes absolute sense!
Datum features B and C must be used simultaneously to generate datum B-C. Both datum features (B and C) will be utilized at their Maximum Material Conditions (MMC) conditions. MMC means: low limit of size for an internal feature; maximum limit of size for an external feature.
Have you received any training on GD&T? Because explaining this in the necessary detail may not help you much if you missed out on the basics.
Let us know.
Stijloor.
D
David DeLong
Now that I have seen the drawing, here is what it means:
Positional tolerance of a diametrical tolerance zone of 1 mm relative to datum A (plane), secondary datums B - C at MMC and tertiary datum D.
The secondary datums are incorrect though. Datum B is a hole and MMC is the smallest allowable size. Datum B by itself should have been the secondary datum.
I could not find datum C on the drawing but I will assume that it is another hole. This should have been the tertiary datum rather than part of the secondary.
Datum B is the 4 way locator and all dimensions should come from this hole. A cylindrical pin of the smallest allowable size should go into this hole on the checking fixture. The real tertiary datum, which should be datum C, is a 2 way locator and is only used for orienting the part about datum B. A cylindrical pin (could be elliptical) would be used on the checking fixture here.
Datum D (could not find it) is not needed and should not be used.
Positional tolerance of a diametrical tolerance zone of 1 mm relative to datum A (plane), secondary datums B - C at MMC and tertiary datum D.
The secondary datums are incorrect though. Datum B is a hole and MMC is the smallest allowable size. Datum B by itself should have been the secondary datum.
I could not find datum C on the drawing but I will assume that it is another hole. This should have been the tertiary datum rather than part of the secondary.
Datum B is the 4 way locator and all dimensions should come from this hole. A cylindrical pin of the smallest allowable size should go into this hole on the checking fixture. The real tertiary datum, which should be datum C, is a 2 way locator and is only used for orienting the part about datum B. A cylindrical pin (could be elliptical) would be used on the checking fixture here.
Datum D (could not find it) is not needed and should not be used.
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