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Flatness tolerance
3

Flatness tolerance

Flatness tolerance

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

RE: Flatness tolerance

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

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

RE: Flatness tolerance

0.1 for A
0.4 for B

RE: Flatness tolerance

(OP)
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.

RE: Flatness tolerance

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.

RE: Flatness tolerance

2
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

RE: Flatness tolerance

(OP)
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.

RE: Flatness tolerance

(OP)
0.3?

RE: Flatness tolerance

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

RE: Flatness tolerance

(OP)
lolx, Thanx, Can i get that solutions?

RE: Flatness tolerance

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

RE: Flatness tolerance

(OP)
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.

RE: Flatness tolerance

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.

RE: Flatness tolerance

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

RE: Flatness tolerance

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.

RE: Flatness tolerance

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

RE: Flatness tolerance

(OP)
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?

RE: Flatness tolerance

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

RE: Flatness tolerance

waqasmalik (Mechanical)is talking about the maximum permissible flatness for both the faces & it is 0.4

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