Questions on drawing reading
Questions on drawing reading
(OP)
Following are my questions when I read this drawing:
1. The drawing shows a movable gage (chuck or collet) to create datum X and datum Y (because of the diameter size Ø.250+.002-.003 is not a basic dimension), then how to check the profile tolerance between A and B (or C and D) since these portion covered by the gage.
2. Is it legal to designate two different datum (X and L or Y and M) on the same feature?
3. Is it correct to have a between symbol on position tolerance callout?
4. Is it legal for two different tolerance callouts on the same feature?
Profile line control |profile line|.006| between E and F.
Circular runout control |Circular runout|.006|L| from section A-A.
Thanks for your comments
SeasonLee
1. The drawing shows a movable gage (chuck or collet) to create datum X and datum Y (because of the diameter size Ø.250+.002-.003 is not a basic dimension), then how to check the profile tolerance between A and B (or C and D) since these portion covered by the gage.
2. Is it legal to designate two different datum (X and L or Y and M) on the same feature?
3. Is it correct to have a between symbol on position tolerance callout?
4. Is it legal for two different tolerance callouts on the same feature?
Profile line control |profile line|.006| between E and F.
Circular runout control |Circular runout|.006|L| from section A-A.
Thanks for your comments
SeasonLee





RE: Questions on drawing reading
2. Again, X & Y are datum points, not the entire feature. Potentially this could be legal.
3. I think this is probably legal. It's telling you the position is only required on the diameter for the length of .538 shown in the above view where X & Y are indicated (not same as X & Y datum targets). The rest of the diameter still needs to be controlled by other tolerances though.
4.
KENAT,
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RE: Questions on drawing reading
Please note the profile callout
|profile|.006|X|L-M|N| X is primary datum
|profile|.006|Y|L-M|N| Y is primary datum
So, X and Y here is not just a datum point.
SeasonLee
RE: Questions on drawing reading
SeasonLee
RE: Questions on drawing reading
I agree the profile call outs may not be valid as normally a single datum point wouldn't form a plane for the primary datum, however this is on the limits of my GD&T comfort zone. I'm not quite sure what they're trying to achieve with the L-M. If They mean the plane through L, oriented by M then I would have thought this was the primary datum.
There appear to be several problems with the drawing, I tried to limit my initial post to answering your questions as best I could.
KENAT,
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RE: Questions on drawing reading
Any similar opinions?
RE: Questions on drawing reading
Regarding similar opinions of the drawing, considering that I have no clue what the application of this part is, it would be unproductive for me to speculate on whether or not the tolerancing scheme is excessive or not, if there is such a thing, especially since that's not what the OP asked. Why would being specific in your requirements equate to an overly expensive part? What would you change about this tolerancing scheme to make it "cheaper"?
Powerhound, GDTP T-0419
Production Manager
Inventor 2009
Mastercam X3
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Questions on drawing reading
KENAT,
Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Questions on drawing reading
I think X and Y designated as both datum and between points, they are used repeatedly, it's a problem need to be corrected for sure. My question is shall we use a V-block or movable chuck (or collet) to create the datum X and Y?
Based on what I understood there are no basic diameters given for the datum targets, a variable diameter gage should be used, so how can one to check ( or inspect ) the profile tolerance between point A and B (or C and D) since these portion covered by the variable diameter gage? The designer should think about the part inspection, any suggestions to solve this problem?
From what I know, it's a shackle used on padlock, would you mind to talk more on the "cheaper" design, which feature tolerance need to be changed?
SeasonLee
RE: Questions on drawing reading
N is not required in the FCF for posn tol of .115 and .250 dias.
targets x and y are misapplied
Response to the OP.
2. No
3. No
4. No
RE: Questions on drawing reading
The question of a cheaper design was directed at ringster since he seemed to already know what the function of the part was.
The X1 and Y1 are either datum "points" or a datum line that is not fully defined. A V-block will not work for checking this part WRT a datum point or line.
Powerhound, GDTP T-0419
Production Manager
Inventor 2009
Mastercam X3
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Questions on drawing reading
I was going to state that the diamter callout should read 2X on the left callout, then I realized that it may be easier to state the diameter of the stock material in the material callout note and take care of that requirement.
Here is an assembly drawing I found online for more info for anyone intersted:
Marcelino Vigil
GDTP T-0377
CSWP
RE: Questions on drawing reading
RE: Questions on drawing reading
Powerhound, GDTP T-0419
Production Manager
Inventor 2009
Mastercam X3
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Questions on drawing reading
I think the following concepts that will apply to both profile of surface and profile of line. One unique aspect of profile controls is they can be used with datum feature reference as a related feature control, when datum features are referenced, the tolerance zone is related to DRF.
Profile controls can also be used without datum feature reference as a form control, when no datum features are referenced, the tolerance zone applies where the part surface actually exists.
For this aspect of profile control, I think |profie|.006| between E and F without datum reference is correct since it will control form here, how do you think?
But what makes me confused is the Runout tolerance |runout|.006|L| in section A-A, it will have two different tolerance callout on the same feature, which one should be applied here Profile or Runout?
SeasonLee
RE: Questions on drawing reading
RE: Questions on drawing reading
There is another excellent example of profile of line is from Tec-Ease, the line profile without datum on the first drawing should control the form here. http://www.tec-ease.com/tips/january-06.htm
SeasonLee
RE: Questions on drawing reading
SeasonLee