what is 1:125 actually saying ?

this was previously posted in another fourm ... but got no replies :( :?

this is from someone who hasn't really used metric since the 4th grade ... nearly 39 years ago :/

when I use an engineering metric scale on a Acad drawing and I use the 1:125 what does this mean ... 1 centemeter, 1 milimeter or 1 meter equals 125 meters ?

the bar scale at 150 meters measures 15 on the 1:125 ... that kind of tells me that this perticular drawing is actually 1:1250 ?

normally when I use 1:40 ... I am saying one inch equals 40 feet :)

also any hints of websites where one might get a quick crash course / brush up on metric lingo and conversions

I am all eyes :shock:

1:125 SHOULD mean 1 unit on drawing = 125 units on part or in real world, regardless of unit. It should NOT be hiding any unit conversions, and 1" = 40' may be an allowable scale statement, but I don't think it can be described as 1:40. Even 1":40' is scary. But I'm the wrong guy to ask about inch-pound drafting, my first employer went metric in early 70's, and my second employer was metric when I joined. The only "English" drawings I see are maps.

For a general (but detailed) intro on SI, Google {NIST metric}. NIST has an excellent page on metric system, especially Special Publications (SP) 330 and 811. If you prefer International (British) English, search for {BIPM SI Brochure} instead. All are free downloads.

For drafting practice in particular industries, you may need a Metric Practice guide released for that industry by a professional society. For example IEEE and ASTM release jointly a standard which is now ANSI SI 10. Unfortunately, it is $50, and 95% of it is in the two NIST pubs I mentioned.

I have an old version from when it was IEEE 268. Compared to NIST SP330, it is more proscriptive. When SP330 (or SI Brochure) suggests something "shouldn't" be done, 268 says "shall not" making it binding if you wish to claim conformance. It mentions all dimensions are typically in millimeters to avoid confusion, recommends 100 mm modules or stations, a few things like that. I haven't looked at other industry metric practice standards, so I can't comment on uniformity. However, in the end, they are all derived from and reference SI Brochure or SP330.

this was previously posted in another fourm ... but got no replies :( :?

this is from someone who hasn't really used metric since the 4th grade ... nearly 39 years ago :/

when I use an engineering metric scale on a Acad drawing and I use the 1:125 what does this mean ... 1 centemeter, 1 milimeter or 1 meter equals 125 meters ?

the bar scale at 150 meters measures 15 on the 1:125 ... that kind of tells me that this perticular drawing is actually 1:1250 ?

normally when I use 1:40 ... I am saying one inch equals 40 feet :)

also any hints of websites where one might get a quick crash course / brush up on metric lingo and conversions

I am all eyes :shock:

this was previously posted in another fourm ... but got no replies :( :?

this is from someone who hasn't really used metric since the 4th grade ... nearly 39 years ago :/

when I use an engineering metric scale on a Acad drawing and I use the 1:125 what does this mean ... 1 centemeter, 1 milimeter or 1 meter equals 125 meters ?

the bar scale at 150 meters measures 15 on the 1:125 ... that kind of tells me that this perticular drawing is actually 1:1250 ?

normally when I use 1:40 ... I am saying one inch equals 40 feet :)

also any hints of websites where one might get a quick crash course / brush up on metric lingo and conversions

I am all eyes :shock: