FredC
Diamond
- Joined
- Oct 29, 2010
- Location
- Dewees Texas
I have been making parts to drawings for 40+ years and still do not have a clear understanding of these 3 terms I see on drawings. Sometimes these dimensions are under my control and sometimes they are the result of the tolerances on purchased items.
Nominal: the drawing in hand has this for an assembly of 4 pcs with all the pcs having one or two dimensions affecting the assembled length.
Reference: one drawing in hand calls for facing off .117 the end of an Allen screw (5/8 Allen head) with a Machinery's handbook minimum depth of .307 and coming up with a ".3 Reference depth". If the starting dimension was minimal I could end up with an effective .190 depth.
4GSR this is one of your drawings.
Another drawing in hand has this for am assembled length of 2 pcs with 3 dimensions affecting the final result.
Typical: I have always taken this as a target dimension you would like to get but not always achievable. Maybe an average of purchased items?
Nominal: the drawing in hand has this for an assembly of 4 pcs with all the pcs having one or two dimensions affecting the assembled length.
Reference: one drawing in hand calls for facing off .117 the end of an Allen screw (5/8 Allen head) with a Machinery's handbook minimum depth of .307 and coming up with a ".3 Reference depth". If the starting dimension was minimal I could end up with an effective .190 depth.
4GSR this is one of your drawings.
Another drawing in hand has this for am assembled length of 2 pcs with 3 dimensions affecting the final result.
Typical: I have always taken this as a target dimension you would like to get but not always achievable. Maybe an average of purchased items?