TOLERANCING AN ANGULAR SURFACE WITH A BASIC ANGLE

[bxbzq]

In the '94 std, the fig. 2-14 shows an angular surface defined by combination of linear dimension and basic angle. This figure is not shown the '09 std. Anyone knows why it is removed from '09 std?

 

[drawoh]

bxbzq,

Figure[ ]2.14 in ASME Y14.5M-1994 does not mean a whole lot to me.

The basic dimension requires some sort of feature control frame to define the tolerance. When I do this, I tend to make both the angle and elevation basic, and I use a profile tolerance on the angle. With Figure[ ]2.14, you could apply an angular FCF and allow lots of variation in height.

--
JHG

 

[Belanger]

It's legal because it creates a tolerance zone. There is no FCF because the height tolerance creates the width of the zone. The dimension origin symbol is essential here, though.

That said, I don't really like it myself, for two reasons. First, as drawoh mentions, it's tempting to ask where the feature control frame is. Second, it locks the height and the angle into the same tolerance, which isn't always desirable.

The 2009 standard does indeed change the wording of paragraph 2.14. They now say that profile or angularity "may" be used, which apparently doesn't prohibit the old Fig. 2-14, though it seems to be discouraged by not mentioning it.

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

http://www.gdtseminars.com