GD&T Q&A session - Interpreting FCF (Feature Control Frame)

[CycleMike]

That falls back to the block tol.

Reread the other thread from my last post, they do a good job explaining it. It is exactly what your asking.

This thread is about if the callouts on this print are correct, I think they are acceptable, and I hope I have conviced some others of my reasoning.

I didn't know that the block tolerances applied to basic dimensions. I don't agree that the tolerancing on this print are correct or even complete. To control the rotation of the features in question, you would need to refine for orientation with parallellism or angularity perhaps.

 

[justncredible]

My day is over, but the size of the retangle are not basic.

And yeah good luck calling up a customer and telling them that the GD&T on a print is wrong

Skew the feature and see when you have the points made if you can get it to pass the TP callout. But the feature has to be kept to a normal ±.005 block tol for 3 dec places. For the size callouts.

Now I wonder if my truck will start since no one can inspect a freakin part these days.......

 

[CycleMike]

My day is over, but the size of the retangle are not basic.

And yeah good luck calling up a customer and telling them that the GD&T on a print is wrong

Skew the feature and see when you have the points made if you can get it to pass the TP callout. But the feature has to be kept to a normal ±.005 block tol for 3 dec places. For the size callouts.

Now I wonder if my truck will start since no one can inspect a freakin part these days.......

I have called the customer and have had prints changed. Usually, they didn't even realize it was wrong because no one ever bothered to let them know. Some even thanked me for pointing it out.

I don't think the limits of size of that rectangle control it's orientation either.

 

[justncredible]

.616 from -B- the top of the rectangle should be. Since it is 2 dec places not 3, most likley you get a .005 for each side and the top line would have to be parallel to -B- within .005. If the part is standing on a surface plate located on -B- set the hieght gage to .616 and run it along the top edge of the rectangle, FIM has to be within .005, or it will not meet the print.

 

[CycleMike]

Really, I'm only pointing out that this print is incorrect / incomplete and I think the GD&T gurus here agree with me. I do agree with you that the part can be inspected. If I were doing a layout on this part, I'd report my findings on an ISIR per the print, nothing more. I would also mention to the customer that the print is not complete but not to worry, we are inspecting it as if it were.

 

[justncredible]

And how would you prove that?

You can not cite Y14.5 since it is not specified.

If the print is not complete how can you make the part?

 

[CycleMike]

And how would you prove that?

You can not cite Y14.5 since it is not specified.

If the print is not complete how can you make the part?

This print wouldn't have made it past our advance quality planning review. If the print isn't clear enough, or we don't know which standard the print was drawn to, we'd have to find that out first.

Can you find a standard that this print might be drawn to?

 

[justncredible]

Why would it have to be drawn to a standard?

It only has to follow a rule in a standard if it is declaired, since none is cited it is a implyed engineering intent.

Better yet you find a standard that this is said to be illegal in.

 

[CycleMike]

Since this is turning into a philosophical debate, I will take my leave.

 

[justncredible]

Since this is turning into a philosophical debate, I will take my leave.

No no, you said it is incorrect, explain how and why? Justify your stance. This is black and white there is no guessing, make your case.