Flatness tolerance 3

[waqasmalik]

Attached figure has been taken from the Alex Krulikowski book of GDT Fundamentals.
My answers are 0.4 for both blanks.Am i right?

 

[Belanger]

Yes (as long as we're assuming ASME rules).

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[waqasmalik]

Thanx JP

What about this one.

My answers are
0.1 for A and 0.5 for B

 

[gabimo]

0.1 for A
0.4 for B

 

[waqasmalik]

gabimot
when Rule 1 applies then indirect flatness control exist for both surfaces.It will be 0.4 for both surfaces when part is at LMC.If surface A is limited to 0.1 then surface B will be 0.3 + 0.4 =0.7.
I mistakenly wrote 0.5 for B.

 

[gabimo]

So your answer is 0.1 for A and 0.7 for B? Please confirm.
I will stick with 0.1 for A and 0.4 for B.
Let's wait for more people to review the question.

 

[Belanger]

The answers are 0.1 and 0.4.
Both numbers won't happen at the same time, however. The key is that the question asks about the maximum permissible error. In order for surface B to get the 0.4 amount, surface A would have to be perfectly flat.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[waqasmalik]

ok, JP.
I got your point. For B to have 0.4 which is maximum allowable A will have to be perfectly flat.

what will be the allowable flatness error for surface B? Not maximum this time.

 

[waqasmalik]

0.3?

 

[Belanger]

Right -- I guess I was thinking of a situation where someone tries to lump all possible dimensions/tolerances together at their maximums at the same time.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[waqasmalik]

lolx, Thanx, Can i get that solutions?

 

[CheckerHater]

I was thinking of a situation where someone tries to lump all possible dimensions/tolerances together at their maximums at the same time.

Me too:

 

[Belanger]

Yeah, CH, but that's not at its maximum dimension. IOW, perfect form at MMC, or maximum bow at LMC, but not both. The in-between stuff is possible. Sorry if I confused things -- just stick with my main answer to the OP

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[waqasmalik]

YUP
"The answers are 0.1 and 0.4.
Both numbers won't happen at the same time, however. The key is that the question asks about the maximum permissible error. In order for surface B to get the 0.4 amount, surface A would have to be perfectly flat."
This clears all.

 

[pmarc]

waqasmalik,
0.4 and 0.4 in the first question, and 0.4 and 0.1 in the second question CAN happen at the same time.
Figure 4-3 from Alex's "Fundamentals of GD&T" (2nd edition) clearly shows that 0.4 and 0.4 at the same time is possible.
And CH's figure clearly proves that 0.4 and 0.1 CAN happen at the same too. This should not be a surprise - if 0.4 and 0.4 makes sense, then 0.4 and 0.1 must also make sense.

 

[Belanger]

Yes, I already acknowledged my mixup. I was thinking of another question in Alex's book near that one asking about the max allowable height or boundary, in concert with these two flatness possibilities.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[pmarc]

J-P,
I know you already acknowledged that.
Waqasmalik quoted your reply and said it cleared all, so I just wanted to be sure that he noticed the mixup too.

 

[waqasmalik]

Yup, i too mistook it.I had attached that figure which pmarc is referring.
Thanx pmarc, special thanx to JP,checkhater

 

[waqasmalik]

one more question plz.
If i apply a flatness tolerance of 0.3 for surface A then flatness tolerance for surface B will remain 0.4?

 

[pmarc]

Yes, the maximum possible flatness error of surface B would still be 0.4.