GD&T Parallelism Question, 9 Engineers Stumped 2

[severeundersteer3000]

[–]svereundersteer 1 point 4 minutes ago

So I want to control the consistency of the thickness of this large metal plate. I don't actually care about the dimension of the thickness, or the parallelism of the part. 9 of us engineers have no ideas and we even hired a GD&T expert to consult us on it and he was stumped.

Its failing this parallelism GD&T often in inspection, but I usually end up with a consistent thickness this way. My current GD&T just doesn't communicate what I want it to.

Any ideas?

 

[SDETERS]

Could you apply a straightness to the thickness FOS dimension?

 

[CheckerHater]

Could you apply a straightness to the thickness FOS dimension?

You have to be careful with terminology.

Straightness is applied to surface element or derived median line.
In case of median line straightness symbol is combined with FOS dimension, but median line implies cylindrical body.
For the body that has "thickness" straightness symbol is applied to surface which may be controlled by FOS dimension.

Since your question was slightly off-topic you could benefit from starting separate thread.


"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

 

[SDETERS]

Never mind. I see this has been discontinued practice in ASME y14.5-2009 D.3. The practice of using straightness to control the flatness of a derived median plane has discontinued. I see what you are now saying Checkerhater. I am learning this stuff. We are still using Asme Y14.5-1994 standard.

 

[desertfox]

Hi

Well I don't see anything wrong with the parallel tolerance but if the part is failing inspection after grinding, it suggests to me is that there might be residual stress in the component which is released post grinding.
Is there any stress relief called for on the component prior to final grinding?

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein