Engineering Drawing Notations 1

[ukesoccer]

I'm really having trouble locating standard notations for engineering drawings.

The biggest problem I'm having right now is understand crosshair notations for holes. I'm trying to interpret a 20 year old Mylar from Canadair (Bombardier Aerospace)

Its hole locations for a 0.190" Al 2024 part, identified by a + with numerous notations

Here are some examples

BB|4N
-----
CC|

BJ|5
-----
|

BA|5F
-----
C|

AO|4F
-----
|4

For example the number in the top right would be the dia. in 32nds, I think, C stands for countersink in the bottom left. But I really dont understand the top left? Or unless Im reading this completely wrong
Any idea????

 

[cstru]

This is actually a rivet identification callout.

BB represents a specific rivet

4N represents the length and the mfr head is near side

CC represents that the rivet is double flushed

Look at spec nas523 Rivet Identification Spec

Hope this helps...