【转帖】controlling positional tolerance of a slot axis

yang686526

controlling positional tolerance of a slot axis
i have a slot (elongated hole) on my part which i wish to give a positional tolerance.  the size tolerance for the slot is given, but i wish to control the centre of the slot within a diamteral zone.  can i use the diameter symbol in the fcf?  i am getting conflicting answers within my organization, so i thought i'd throw it out there.
thanks,
jeff
find a job or post a job opening
no.  since this is a non-circular element, you need to control the center planes, as opposed to the axis.
maybe check out
umm...
slots are best controlled with two fcbs, one for the vertical axis and one for the horizontal.  granted, you do end up with a rectangular tolerance zone, but you have more control over it than you would with the square tolerance zone that +/- dimensioning would give you.
oops, sorry. i did a search, didn't realize it was yours.
anyway, i agree with ewh.
chris
sr. mechanical designer, cad
solidworks 05 sp1.1 / pdmworks 05
okay, i think i understand.  now when would a "boundary" callout be appropriate?
jeff
jmarkus,
   the gd&t positional tolerance is not just for round things and holes.  check out page 92 in asme y154.5m-1994, where they apply it to a pitch circle of rectangular slots.
   i have only one objection.  the whole point of a slot is that you only need to be accurate in one direction.  the positional tolerance controls two.
                     jhg
in the y14.5 training i had, we did a slot with the width controlled by true position of .001 and the length controlled by true position of .020.
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ben loosli
cad/cam system analyst
ingersoll-rand