Symmetry Annotation
Symmetry Annotation
(OP)
Hi,
I'm working on some drawings (making new drawings for reference) for a steel arch bridge built back in 1893, and have some of the original shop drawings.
On some of the drawings only one-half of the part is drawn (up to the Centerline) and noted: "SYM ABT CENTERLINE".
Am I right in assuming this means symmetrical about centerline, if so is this annotation still used today?, if not what else would be used.
Many thanks,
Gord
I'm working on some drawings (making new drawings for reference) for a steel arch bridge built back in 1893, and have some of the original shop drawings.
On some of the drawings only one-half of the part is drawn (up to the Centerline) and noted: "SYM ABT CENTERLINE".
Am I right in assuming this means symmetrical about centerline, if so is this annotation still used today?, if not what else would be used.
Many thanks,
Gord





RE: Symmetry Annotation
RE: Symmetry Annotation
Yes your assumption is correct and I have recently seen CAD drawings using the same terms.
desertfox
RE: Symmetry Annotation
What you're talking about is subtly different but I think the idea is still shown in the relevant ASME spec whose number escapes me and I'm not at work to look.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Symmetry Annotation
My CAD system will make a half view and place 2 parallel lines at either end of a symmetry line per either ISO or ASME. I don't know which specific parts of the standards cover this.
RE: Symmetry Annotation
Y14.5M-1994 shows what you have described in the figure per my above statement.
Frank
RE: Symmetry Annotation
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?