Almost every engineering drawing carries dimensions without an individual tolerance \u2014 and they are still not \u201ctolerance-free\u201d. What applies to them is the general tolerance from the title block, usually to ISO 2768. In the inspection plan these are exactly the dimensions that get handled badly: sometimes forgotten, sometimes carried without a tolerance. Both come back to bite you at the first article inspection at the latest.<\/p>\n
ISO 2768 defines general tolerances for dimensions without an individual tolerance. Part 1 covers linear and angular dimensions in four classes (f = fine, m = medium, c = coarse, v = very coarse), Part 2 covers form and position in classes H, K and L. So an entry such as \u201cISO 2768-mK\u201d<\/strong> in the title block means: linear dimensions to class m, form and position to class K. The permissible deviation depends on the nominal size range \u2014 a 20 mm dimension in class m may vary by \u00b10.2 mm, a 200 mm dimension already by \u00b10.5 mm.<\/p>\n A dimension without an individual tolerance is still a characteristic: it describes the geometry of the part, and the customer may expect it to lie within the general tolerance. Leave such dimensions out when ballooning and you deliver an incomplete first article inspection report \u2014 write them into the characteristic list without a tolerance and nobody can decide \u201cpass\u201d or \u201cfail\u201d when measuring. The clean approach: every one of these dimensions gets its numbered balloon, and the characteristic list carries the limit deviation derived from the class and the nominal size range.<\/p>\n During automatic detection, DrawingStamp Pro also balloons the dimensions without an individual tolerance and lists them in the exported characteristic list \u2014 so they do not drop out of the inspection plan merely because no tolerance is printed beside them. Dimensions in brackets are skipped by default and can be included deliberately if your customer requires it. Assigning the correct tolerance class from the title block remains a conscious look by the inspector \u2014 precisely the look that turns a list into a dependable inspection plan.<\/p>\nWhy these dimensions belong in the inspection plan<\/h2>\n
Three traps from daily practice<\/h2>\n
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How the software helps<\/h2>\n