fraction used in fabrication ................drawings

[Edwinhgsystems]

writing a engineering manual
Topic 1
I have done some research in DRM amd ASME manuals on fractions units.Nothing is mention of this US unit.If it is used or mentioned, which US std manual is fractions documented.Reason is that we currently using fabricator ( welders) to build our parts as per fractions drawings. All measuring tapes in the US are fractions and not decimals.I know if we switch to the metric system, it will eliminate the use of fraction on all engineering drawings.

Topic 2
The letter " x "
When used in a phrase "20 x 10 x 1/2 in" Which case should be used, upper or lower case and why?. Is there a std or a rule?

Topic 3
The trailing zeros after the decimal point whether it metric or inch units.Who or how ? determine the number of zeros?
see ASME Y14.5M

 

[KENAT]

It appears you're using ASME mechanical drawing stds, though you don't say what version so take below with pinch of salt if it doesn't match the version you use.

Topic 1

Decimal dimensioning shall be used on drawings except where certain commercial commodities are identified by standardized nominal designations, such as pipe and lumber sizes.

All measuring tapes in the US are fractions and not decimals.

This is a patently untrue statement. Whilst the typical inch measure you'd pick up at home depot etc would be fractional it is possible to obtain decimal inch tape measures. I found several sites selling them with a quick Google search. Plus even if using decimals on the drawing, you could always make sure they correspond to fractional sizes if appropriate e.g X.125, X.25, X.375 ...


TOPIC 2

ASME Y14.5M-1995 section 1.9.5 & Appendix C-2 explicitly show upper case X. Generally, except for certain unit labels, all text on drawings is upper case this may be stated in Y14.2 but I'm not sure.

TOPIC 3

ASME Y14.5M-1994 section 1.6 has some information but I'm not sure it directly answers your questions if you are referring to the way many block tolerances are based on number of decimal places for inch drawings.



forum1103 is generally a better place for this type of query.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​