【转帖】implied 90

yang686526

implied 90
do the titleblock tolerances apply to implied 90 degree angles?
yes they do.
dave d.
thats what i thought...thanks for verifying dave.
in you drawing border when you state interpret all dimensions and tolerances per asme y14.5m - 1994 you invoke the fundamental rules unless otherwise specified on the drawing.
section 1.4 fundamental rules: dimensioning and tolerancing shall clearly define engineering intent and shall conform to the following.
a)each dimension shall have a tolerance, except for those dimensions specifically identified as reference, maximum, minimum or stock (commercial stock size).  the tolerance may be applied directly to the dimension, indicated by a general note, or located in a supplementary block of the drawing format.
b)dimensioning and tolerancing shall be complete so there is full understanding of the characteristics of each feature.
c)each necessary dimension of an end product shall be shown.  no more dimensions than those necessary for complete definition shall be given.  the use of reference dimensions on a drawing should be minimized.
d)dimensions shall be selected and arranged to suite the function and mating relationship of a part and shall not be subjected to more than one interpretation.
e)the drawing should define a part without specifying manufacturing methods.  thus, only the diameter of a hole is given without indicating whether it is to be drilled, reamed, punched or made by any other operation.  however, in those instances where manufacturing, processing, quality assurance, or environmental information is essential to the definition of engineering requirements, it shall be specified on the drawing or in a document referenced on the drawing
f)it is permissible to identify as nonmandatory certain processing dimensions that provide for finish allowance, shrink allowance, and other requirements, provided the final dimensions are given on the drawing.
g)dimensions should be arranged to provide required information for optimum readability.  dimensions should be shown in true profile views and refer to visible outlines.
h)wires, cables, sheets, rods, and other materials manufactured to gage or code numbers shall be specified by linear dimensions indicating the diameter or thickness.  gage or code numbers may be shown in parentheses following the dimension.
i)a 90 degree angle applies where center lines and line depicting features are shown on a drawing at right angles and no angle is specified.
j)a 90 degree basic angle applies where center lines of features in a pattern or surfaces shown at right angles on a drawing are located or defined by basic dimensions and no angle is specified.
k)unless otherwise specified, all dimensions are applicable at 20 degrees celsius (68 def f).  compensation may be made for measurements made at other temperatures.
l)all dimensions and tolerances apply in a free state condition.  this principle does not apply to non-rigid parts as defined in paras 2.7.1.3(b) and 6.8.
m)unless otherwise specified, all geometric tolerances apply for full depth, length and width of a feature.
n)dimensions and tolerances apply only at the drawing level where they are specified.  a dimension specified for a given feature on one level of drawing, is not mandatory for that feature at any other level.
heckler
sr. mechanical engineer
swx 2007 sp 3.0 & pro/e 2001
xp pro sp2.0 p4 3.6 ghz, 1gb ram
nvidia quadro fx 1400
      o
  _`\(,_
(_)/ (_)
(in reference to david beckham) "he can't kick with his left foot, he can't tackle, he can't head the ball and he doesn't score many goals. apart from that, he's all right."  -- george best
thanks heckler, saved me trying to find i & j and type them out.
depending on the exact nature of the feature, sometimes the =- linear dimension can also come into play as well as the 90°.
kenat, probably the least qualified checker you'll ever meet...
thanks for all you input. regarding the application and being instructed not to use gd&t. i just needed to know that the implied 90 was linked to the t-block tolerance of +/- 1 degree so i can tighten the angle at which a hole for a linear sensor is positioned to avoid unacceptable angular misalignment in my tolerance stack. i apologize for confusion. thanks again to all.
a star for heckler's unauthorized reproduction and publication.  making my own copy before the copyright cops close in!
you know i've often thought about that.  in my posts i'll sometimes put a couple of paragraphs from the standard.
kenat, probably the least qualified checker you'll ever meet...
i guess that would depend on ones definition of reproduce.  
i will make the appropriate adjustments in my future posts because my intent was not to break any copyright laws but to inform the folks that seek help.
heckler
sr. mechanical engineer
swx 2007 sp 3.0 & pro/e 2001
xp pro sp2.0 p4 3.6 ghz, 1gb ram
nvidia quadro fx 1400
      o
  _`\(,_
(_)/ (_)
"first they ignore you, then they ridicule you, then they fight you, then you win." - mahatma gandhi
so, if you base your company drawing standard on asme and hence perhaps copy some things verbatum, does that infringe the copyright?
heckler, i wouldn't worry to much.  if it's a concern the moderator can take action can't they?
kenat, probably the least qualified checker you'll ever meet...
i see no problem with it, especially since credit is always given.  if it weren't, we wouldn't pay as much attention, would we?