【转帖】block tolerances applied to comercial hardware

yang686526

block tolerances applied to comercial hardware
at my company the documents are all controlled by a program. when the program was initiated it automatically took all parts in inventory and generated  prints for them. if the part already had a print, it was uploaded into the system, and if it had no print it was loaded into a commercial print. for these parts the description, supplier, and any additional notes where put in text boxes in the center of the print inside our standard page border. we started having problems when incoming inspection applyed the block tolerance from the page border to dimensions in the description. i want to remove the block tolerance from the border on commercial parts and make the dimensions reference, but i am not sure if that is what is best. i wish we could just have an excel spreadsheet for commercial parts but that is not an option. what is the industry standard for making prints of commercial parts and is there a specification to support this?
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control drawings asme y14.24-1999 section 8
kenat,
laynec,
quote:
...when the program was initiated it automatically took all parts in inventory and generated  prints for them...
   i am unable to believe that a computer program could automatically generate a decent quality drawing of a custom component.  at the very least, some human has to examine the drawing and work out what information goes on it.  dimensions and tolerances are not necessarily important.  this is especially true for specification controls.  you need to control up the gear ratio, the capacitance, the maximum cfm, the paint colour, etc.  what is the point of your inspector using these drawings, otherwise?
   are your tolerance blocks your one and only problem, or is this just the tip of an iceberg?  
                        jhg
i agree with drawoh - i just answered the stated question i didn't look further into it.
simplistically, if the drawings were completely generated 'automatically' from some kind of part description then yeah the block tolerance is meaningless.
in fact trying to do tolerance for vendor parts even if you have a control drawing can be problematic, especially on vendor items that are actually assemblies.
  
kenat,
if you make the dimensions reference, then the block dimensions don't matter.  likewise for specifying tolerances on dimensions.
that's one work around.  or a simpler one in this case may be to remove the tol block and just have a note that all dimensions are reference.
of course, this only works if you don't need the dimensional controls.
kenat,
thetick,
   part of the op's problem is that incoming inspection is rejecting stuff based on the drawings.  i dream of people taking my drawings that seriously.  
   the problem with this is that your drawings have to contain useful information.  this makes the inspection useful, and it keeps people respecting your drawings.
   at some point, people are doing to decide that we are idiots, and that we really don't mean the stuff we put our drawings.
                          jhg
why not just use spec sheet formats and forgo the drawings?  you do not control the specifications for the commercial parts, so you should have drawings for it.   
matt lorono
cad engineer/ecn analyst
silicon valley, ca