Redundant or not? Please help
Redundant or not? Please help
(OP)
Imagine a shaft --datum A-- Ø.365/.360-- with 2 thru holes 2x Ø.195/190--positioned with ± .185/.165 tolerance from each end of the shaft.
A slot is added to this shaft in the middle (equal distance from both ends). The slot is .100/.090 and is called datum B
The GD&T is as follow:
For the holes: multiple single segment (not composite )
2x
position of Ø.002 at MMC to A at MMC--first segment
and
position of Ø .004 at MMC to B at MMC--second segment--
For the slot (datum B): position of Ø.002 at MMC with A at MMC
The question for you is: the second segment of the multiple segment callout, isn't it redundant callout?
Simultaneous requirement is implied, since the slot and the holes have the same datum reference frame (positional at MMC to A at MMC). Please help.
Again, I am thinking that position of Ø .004 at MMC to B at MMC--second segment--is redundant, but I am not sure.
A slot is added to this shaft in the middle (equal distance from both ends). The slot is .100/.090 and is called datum B
The GD&T is as follow:
For the holes: multiple single segment (not composite )
2x
position of Ø.002 at MMC to A at MMC--first segment
and
position of Ø .004 at MMC to B at MMC--second segment--
For the slot (datum B): position of Ø.002 at MMC with A at MMC
The question for you is: the second segment of the multiple segment callout, isn't it redundant callout?
Simultaneous requirement is implied, since the slot and the holes have the same datum reference frame (positional at MMC to A at MMC). Please help.
Again, I am thinking that position of Ø .004 at MMC to B at MMC--second segment--is redundant, but I am not sure.





RE: Redundant or not? Please help
The centerplane of Datum B, by itself will not really establish a cylindrical zone control, while it is not actually wrong to use it it seems like it is not really what is desired, Without a functional assembly definition who knows?
Frank
RE: Redundant or not? Please help
RE: Redundant or not? Please help
Second, the true position call out on the keyway is incorrect. There is no way this can be a cylindrical tolerance zone.
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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
RE: Redundant or not? Please help
I stand by what I said, Understaning the difference in the effect of datum B as primary vs just A(primary), or A(primary), B(secondary) which I suspect is actually more of the functional requirement requires a more complex analysis than I have to review quickly now here. It would be easier to build the functional gages, which is why the standard uses this method.
Frank
RE: Redundant or not? Please help
Frank
RE: Redundant or not? Please help
To dgallup:
I agree with your second statement. No diametral symbol Ø on the tru position callout on the keyway.
As far as the first statement, I am inclined to disagree because the simultaneous condition. See the standard ASME Y14.5 -2009 page 80 --the same is applicable on the 1994 standard.
Am I missing something? The keyway must be alligned withthe holes due to the same datum reference frame which means simultaneous condition, right?
RE: Redundant or not? Please help
Frank"
Here everybody --including me --agree. No Ø for the keyway callout!
RE: Redundant or not? Please help
Frank
RE: Redundant or not? Please help
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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
RE: Redundant or not? Please help
I have also said I suspect I would have not done it that way.Then when you add a: "do I care that much about this particular feature", you may be there.
Frank
RE: Redundant or not? Please help
Frank
RE: Redundant or not? Please help
Frank
RE: Redundant or not? Please help
a multiple single segment position control within dia .004(M)/A(M)/B(M) on the first level, and within dia .002(M)/A(M) on the second level.
This allows the greater position wrt datum-B, with a refinement wrt datum-A, including the inter-feature relationship. I think that was the design intent. Datum feature B is related back to datum-A, so tying the two controls together as a composite makes sense.
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com
RE: Redundant or not? Please help
The OP was: "is it the same" (redundant), I assume you agree it is not the same?
Frank
RE: Redundant or not? Please help
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com
RE: Redundant or not? Please help
"Jim,
The OP was: "is it the same" (redundant), I assume you agree it is not the same?
Frank "
Jim,
Yes, my original question was the following:
- As is now the drawing defined (not as should have been) is the second positional requirement (the one from the multiple segment) redundant or not, taking in consideration impled simultaneous requirement rule, which is aplicable in this case--
Jim ,
Thank you for your input on how the drawing should have been at the begining to most likely meet the design intent, but unfortunatly did not end up like should. Therefore, created questions and I needed your input.
RE: Redundant or not? Please help
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com
RE: Redundant or not? Please help
This may not be directly related to OP, but is everyone here comfortable with using Diameter symbols AT ALL?
As holes are located North-South via FCF and East-West via directly toleranced dimensions, is tolerance zone really cylindrical?
RE: Redundant or not? Please help
I agree with you that this print needs a lot of work (including Ø symbol usage, missing basic dimensions, combination between ± dimensioning and GD&T and so on), but the original question was if that callout is redundant or not pretending everything else is as per the standard.
In other words, if the designer revise this drawing per the standard Y14.5-1994 and everything now is fully defined and legal, but is keeps the same GD&T structure, is that structure redundant or not. That was the original question and I want to understand the concept and the "conflict" (if any) between these GD&T requirements. I hope this helps.
RE: Redundant or not? Please help
I started my post saying that it was more about "legal" then "redundant".
One of my concerns was that if the shape of tolerance zones are significantly different, requirements may be less redundant, but it is not the case here.
Also there is another fine line here. As datum [A] symbol is not aligned with 365/360 dimension, the datum [A] is NOT axis of the shaft, but rather something else, it creates different reference frame, and your requirements are NOT redundant.
There is no need to be defensive. I am just exploring possibilities.
RE: Redundant or not? Please help
I believe in the case of a cylinder, sphere or cone (without other limiting indications) it is treated as the same thing.
Frank
RE: Redundant or not? Please help
RE: Redundant or not? Please help
Frank
RE: Redundant or not? Please help
The case of a planar feature of size is different, though, because there the datum symbol not aligned with the FOS would mean only a surface as the datum feature.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Redundant or not? Please help
This is the way it was explaind to me also, if I put a finish mark on the surface it is automatically applied all way around on a cylinder, sphere, or cone. so the standards are consistant in that sense.
Frank
RE: Redundant or not? Please help
Where exactly in the standard datum derived from cylinder is shown like in OP picture?
RE: Redundant or not? Please help
As there is no other reasonable interpretation, the interpretation leads you to the center axis; this is supported by the attachment of the datum callout to the cylindrical surface in an end view (see Fig.4-44 in'09, datum A). Note that a similar situation arises when attaching the datum callout to the side-profile of a cone, as in Fig. 4-45 ('09).
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com
RE: Redundant or not? Please help
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Redundant or not? Please help
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Redundant or not? Please help
Paragraph 3.3.2(c)states "see Fig.3-4, illustrations (e) and (g)" plain and simple.
I see no reason to continue this argument.
RE: Redundant or not? Please help
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Redundant or not? Please help
btw, don't recall noticing (c) on Fig. 3-4 ('09) previously. Have taught (h) & (f), though I've had people argue with me about their validity.
Also, I had mentioned the callout for cones for the very reason that J-P mentions; it sets precedence for cylinders, whether or not explicitly laid out in the text or other graphics.
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com
RE: Redundant or not? Please help
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Redundant or not? Please help
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com