Bayonet feature tolerance

[Ryan615]

Hi folks,

I have a question about controlling the dimensions of a bayonet feature on one of our parts. For the current drawing rev, the parts seem over dimensioned. Also, the machinist don't really consider the relief between and below the lugs to be one feature (everything highlighted in blue in IMAGE 1). Typically, the relief below the lugs is not blended well with the relief between the lugs, which can be problematic (I understand the blend is difficult, but...). Our machine shop insisted that we dimension similar to the scheme in IMAGE 3&4. Top view (IMAGE 3) shows the R3.19 dimension as basic and the all around profile tolerance of 0.015. Top view (IMAGE 4) shows the relief between the lugs dimensioned and toleranced (6.38 in. Dia). To me, this suggests that the profile tolerance is limited in height to the thickness of the lugs.

I would like to do something similar to what is in IMAGE 5&6. The 0.015 profile tolerance applies all around between S and T. I think this would be interpreted as intended, that is, all the blue highlighted surfaces of IMAGE 2 would be controlled by the 0.015 profile W.R.T A B C. This scheme seems to do a better job of defining design intent.

At least, it does in my mind... What say you all? Is this a legal move in Y14.5-1994? Am I correctly applying and interpreting? I'm certainly no GD&T expert. I've had some training in the 2009 standard, but I rarely get to apply what I've learned. I would greatly appreciate any pointers.

IMAGE 1

IMAGE 2

IMAGE 3

IMAGE 4

IMAGE 5

IMAGE 6

Thanks!

-Ryan

 

[Ryan615]

Any thoughts on this one? I will handle this in a way that appeases the production crew, but I am curious if the call out in IMAGE 5&6 is interpreted correctly.

Thanks,

Ryan

 

[ewh]

The images don't show for me...

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[ctopher]

No images for me too.

Chris, CSWA
SolidWorks 14
SolidWorks Legion

 

[Belanger]

I can see the images on my work computer, but not home computer. Strange.

This is a tricky one, but I don't think the scheme proposed in Image 5 would work. The Y14.5 standard sees the "all around" symbol as literally meaning all around the perimeter of what you're pointing to in the view shown, not in the usual way that we would think of that surface in 3-D as it wraps around the circular inside of the part.

The solution might actually be closer to what they suggested in Image 3. If the clarity is in doubt, you can always add a note near the feature control frame to explain the area of coverage, such as "shaded area only, as shown in View X" or similar.

Interesting to hear of other suggestions, but I at least wanted to chime in with some initial input for you.

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

 

[Ryan615]

Try these:

IMAGE 1

IMAGE 2

IMAGE 3

IMAGE 4

IMAGE 5

IMAGE 6

Tried to make it simple, but the embedded files are not working for everyone. Sorry!

-Ryan