【转帖】parallelism gd t and angle connection

yang686526

parallelism gd & t and angle connection
hi,
could you help me interpret the parallelism gd & t. figure is attached.
i have shown my interpretation , i am not sure which one is correct.
parallelism defines a set of parallel planes at the given distance from the specified datum.  all points of the controlled surface must lie within the limits of those planes.
ringman,
it is true but in both of my cases set of the parallel planes will lie at distance of 0.2. only difference being in first case it is equally offset by 0.1 in both direction in other case 0.2 in one direction.   
im not sure that i understand the 2/50 in the fcf.  i think you may have a problem there.
then there is the question is this per y14.5?
parallelism is a refinement control. in fig. 6-15 the profile is 0.4 with the additional requirement that within that 0.4 zone, it be parallel with 0.12 - the 0.12 may not violate the 0.4 profile zone.
on a limit dimension, the upper and lower limits set up the zone, the parallelism should be a refinement of those limits.
ringman,
i have myself seen this kind of notation for first time may be from iso.
but let us forget that part consider only 0.2 instead of 0.5/50 than what is your thought
darn. keep reading these iso questions with the asme glasses on.  
me too, disregard my comments.  intended for y14.5
tost,
   your specification 0.2/50 is identical to just specifying 0.2, given that the length is 50.  
   both of your interpretations are correct.  the total variation from parallel to datum a must not exceed 0.2.  your two diagrams show a different distance between datum a and your edge.  this would be controlled by a ± tolerance, or by a profile fcf.
                     jhg
drawoh: that's how i see it too. the /50 is redundant, but who knows how iso interprets it?
0.2/50 is the first time i have seen this. reduce the print or make multiple copies can make it unrecognizable...possibly make it "0.2150".
also, just curious...not clear to me, is datum a representative of a surface or a centerline?
chris
solidworks/pdmworks 08 3.1
autocad 06/08