【转帖】olerances and decimal places

yang686526

tolerances and decimal places
i would like to know what your opinion is regarding the number of decimal places of form tolerances. asme y14.5 says that inch dimensions and their tolerances should have the same number of decimal places e.g. .500±.125 or .3125±.0010. now, if we add a form tolerance, say circularity. should the form tolerance have the same number of decimal places? for instance, if the dimension is .3125 +.000/-.0030, should the circularity be .0010 or .001?
yes, it should contain the same number of decimal places.
see para 2.3.2(d) of asme y14.5m-1994.
ewh is correct.
also, check your cad settings, some are set to drop the trailing zero.
chris
solidworks 07 4.0/pdmworks 07
autocad 06
trailing zeros must be dropped on metric dimensioned drawings. if the you do both, english and metric, then you will need to adjust your sw settings.
"wildfires are dangerous, hard to control, and economically catastrophic."
ben loosli
ewh, thank you very much for your responce. unfortunately, i think the reason you gave does not apply in this case. paragraph 2.3.2(d) of asme y14.5m-1994 applies to toleraces associated with a basic dimensions. in my example, the feature is a cylinder and it is the primary datum feature.
yes - in inches it is the same number of decimal places
dave d.
why?
yes, metric dims drop trailing zeros.
chris
solidworks 07 4.0/pdmworks 07
autocad 06
the example shown may be of a locational tolerance, but the para does not specify which type of tolerance it applies to, only that the "basic dimension value is expressed with the same number of decimal places as the tolerance."
if you interpret this as meaning that tolerances other than positional are exempt because they are not specifically referred to, you are going to have quite a few problems applying and understanding this standard.
please refer to para 1.1.4.
i believe ewh is correct for decimal inch.
" for instance, if the dimension is .3125 +.000/-.0030, should the circularity be .0010 or .001? "
my understanding of the standard is that it should be:
.3125 +.0000/-.0030 cirulariy .0010
the common element on all 4 cases in 2.3.2 is that the tolerance has the same number of figures as the dimension.
kenat, probably the least qualified checker you'll ever meet...
yes, i was only refering to decimal inches...