MRAHM Posted November 9, 2015 Share Posted November 9, 2015 Hi Just a question which is´t IronCAD specific. I´ve been learned that trailing zeros does´t add any value. In math it does but not in mechanical drawing/design. When I wan´t to describe the degree of deviation from a value I use tolerances. Sometimes it is a +- value. General dimension values refeer to a standard like ISO 2768. Do you have different ways to define a tolerance value in US? For me the precision option in Drawing is strange and out of use. We have general tolerances like ISO 2768 for mechanical design and ISO 13920 that handles welded constructions. For me 32 and 32,00 is the same value and if the drawing refeers to ISO 2768-m both has a tolerated deviation +-0,2. Do you have different ways of handling tolerances? For me the precision option is a bad habbit of controlling deviations (deviations are controlled by standards). What is your opinion? Just want to understand how other people works and why it is there. /micke Quote Link to comment Share on other sites More sharing options...
Mike Hatch Posted November 9, 2015 Share Posted November 9, 2015 Hi, In mechanical drawing terms trailing zeros DO have a value. BS8888 (was BS308) gives the range, generally none = +/- 0.5mm, one = +/- 0.25mm, two = +/- 0.1mm. All drawings (in this company anyway, in the UK) are to BS8888 with the trailing zeros giving generalised tolerances, specifics (fits) are covered with individual marked tolerances per dimension, this keeps a complicated drawing simpler. The precision option sets the drawings general rules, and with us at least, no drawings are produced without the precision option, any drawings without are not valid and only regarded as rough sketches. Mike. Hi Just a question which is´t IronCAD specific. I´ve been learned that trailing zeros does´t add any value. In math it does but not in mechanical drawing/design. When I wan´t to describe the degree of deviation from a value I use tolerances. Sometimes it is a +- value. General dimension values refeer to a standard like ISO 2768. Do you have different ways to define a tolerance value in US? For me the precision option in Drawing is strange and out of use. We have general tolerances like ISO 2768 for mechanical design and ISO 13920 that handles welded constructions. For me 32 and 32,00 is the same value and if the drawing refeers to ISO 2768-m both has a tolerated deviation +-0,2. Do you have different ways of handling tolerances? For me the precision option is a bad habbit of controlling deviations (deviations are controlled by standards). What is your opinion? Just want to understand how other people works and why it is there. /micke 41715[/snapback] Quote Link to comment Share on other sites More sharing options...
bbraho Posted November 9, 2015 Share Posted November 9, 2015 There is a long tradition (pre-dating ISO and BS standards) of using the number of decimal places on a dimension to indicate precision. The rules of how it is interpreted are company specific and when used are indicated in the title block. This tradition has fallen out of use in some sectors (automotive, for example) but remains the de-facto standard in others (industrial machinery). My experience is in the USA, but I have examples in drawings worldwide. Quote Link to comment Share on other sites More sharing options...
MRAHM Posted November 9, 2015 Author Share Posted November 9, 2015 Hi, In mechanical drawing terms trailing zeros DO have a value. BS8888 (was BS308) gives the range, generally none = +/- 0.5mm, one = +/- 0.25mm, two = +/- 0.1mm. All drawings (in this company anyway, in the UK) are to BS8888 with the trailing zeros giving generalised tolerances, specifics (fits) are covered with individual marked tolerances per dimension, this keeps a complicated drawing simpler. The precision option sets the drawings general rules, and with us at least, no drawings are produced without the precision option, any drawings without are not valid and only regarded as rough sketches. Mike. 41717[/snapback] Hi Interesting. That explains why it is there. In Sweden we in general use ISO 2768. Some companies has their own standards and I even know that some depends on the trailing zeros. When you use trailing zeros is´t it many values that needs to be tinkered with? When using ISO 2768 the tolerance depends on the lenght. In my example with a 32mm value it gives the precision of 32+/-0,2 with 2768-m. If it is a part that need higher tolerances in general I can apply 2768-f which gives 32+-0,15. If the length is 315-1000mm then the deviation is +/-0,8 resp +/-0,3. Is it the same with holes and shafts? For a 10mm hole I would say 10H7 to dimension a hole with a tolerance for a guide pin. It gives me a hole with the limits 10,000 and 10,015. Do you put trailing zeros there as well? Quote Link to comment Share on other sites More sharing options...
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