This cannot be correct

[rollingcloud]

I came across a drawing that does not seem to be properly drawn. I think having datum B on the shaft diameter is redundant, the bearing surface should be datum B, and there should no referencing loop between datum A and B as it is currently, do you guys agree?

 

[3DDave]

Position of the thread to B in this fashion is considered a no-no. Perpendicularity would be the allowable. Also should be a diametral zone on the threads.

Not a fan of loops, but not illegal.

 

[greenimi]

3DDave,

Position of the thread to B in this fashion is considered a no-no.

Why?
Beside of missing diametral tolerance zone symbol, why that shown position is a no-no?

I am reading it as the position of the pitch diameter of the thread to be within some TZ from the bearing surface a.k.a datum feature B

 

[3DDave]

Oops - in 85,000 previous examples B is the flat underside.

Yea, sure, A axis position to B axis is fine. Still requires a diameter modifier.